Engine tests; embracing the results of over one hundred feed-water tests and other investigations on various kinds of steam engines, conducted by the author

^_n_n_-n,

REESE LIBRARY

UNIVERSITY OF CALIFORNIA.

'Kfceiiied ,190 .

Accession No. 82891 • Class No.

ENG-INE TESTS

EMBRACING THE RESULTS OF OVER ONE HUNDRED
FEED-WATER TESTS AND OTHER INVESTIGA-
TIONS ON VARIOUS KINDS OF STEAM
ENGINES, CONDUCTED BY
THE AUTHOR,

BY

GEO. H. BABKUS, S.B.

« t

MEMBER OF AMERICAN SOCIETY OF MECHANICAL ENGINEERS, BOSTON

SOCIETY OF CIVIL ENGINEERS, NEW ENGLAND

WATER-WORKS ASSOCIATION.

NEW YORK:

D. VAN NOSTRAND COMPANY
1900

COPVKIGHT, 1900, BY

GEO. H. BAEKUS.

PREFACE.

THE favor with which the author's book on " Boiler Tests,"
published in 1891, has been received, has led him to collect in
similar form the data and results obtained on many of his
engine tests. Some of the tables of results have appeared
from time -to time in mechanical journals and in pamphlets ;
also in the Transactions of the American Society of Mechanical
Engineers, but a large part is now printed for the first time.

It is believed that the data here presented will prove of
value to the engineering profession, to owners and intending,
purchasers of steam plants, and to any who are interested in
the economical production of power. The book should be of
special value to engineers advising intending purchasers of
engines, on account of the assistance it will render in making

a wise selection.

GEO. H. BARRUS.

95 MILK STRKET, BOSTON, March, 1900.

3

82891

CONTENTS.

PART I.

PAGE

INTRODUCTION 9

How THE FEED-WATER TESTS WERE CONDUCTED 12

MEASUREMENT OF THE FEED-WATER 13

INDICATING 18

GENERAL METHOD OF CARRYING ON THE FEED-WATER TEST .... 21

LEAKAGE TESTS OF VALVES AND PISTONS 23

CALIBRATION OF INSTRUMENTS 28

MANNER OF WORKING UP THE TESTS 30

TABLE OF 1875° 39
m. e. p.

PART II.

FEED-WATER TESTS OF SIMPLE ENGINES 43

FEED-WATER TESTS OF COMPOUND ENGINES 131

FEED-WATER TESTS OF TRIPLE EXPANSION ENGINES 235

SUMMARY OF FEED-WATER TESTS 245

REVIEW OF FEED-WATER TESTS fc , 249

I. CYLINDER CONDENSATION AND LEAKAGE ; . . 251

II. EFFECT OF PRESSURE ON THE ECONOMY 258

III. EFFECT OF SPEED UPON ECONOMY 259

IV. ECONOMY OF CONDENSING 261

V. EFFECT OF SUPERHEATING .... 265

VI. RELATIVE ECONOMY OF SIMPLE, COMPOUND, AND TRIPLE EX-
PANSION ENGINES 267

VII. ECONOMY OF STEAM-JACKETING AND RE-HEATING IN COMPOUND

ENGINES „ 270

VIII. EFFECT OF RATIO OF CYLINDER AREAS IN COMPOUND ENGINES, 273

IX. MISCELLANEOUS 274

VALVE SETTING . 279

STEAM-PIPE DIAGRAMS . 321

PART I.

ENGINE TESTS,

INTRODUCTION.

THE first work in the line of engine-testing with which the
author was intimately connected was carried out at the Massa-
chusetts Institute of Technology in the years 1875 to 1878.
During this time he was engaged in conducting the experi-
ments of the late George B. Dixwell on the use of superheated
steam for motive power. , The experiments consisted princi-
pally in investigations on a Corliss engine operated with both
saturated and superheated steam ; and they embraced the deter-
mination of the performance of the engine running under both
of these conditions with different points of cut-off, and with
different degrees of superheating, together with the determina-
tion of the effect of other changes in the conditions of opera-
tion. The engine in question, and the testing apparatus
connected with it, formed the nucleus of a mechanical labora-
tory used in instructing the students of the Institute ; and it
was the first of the many steam laboratories which have been
established in the colleges of this country. In the course of
these investigations a board of experts, consisting of Chief
Engineers Loring, Baker, and Farmer of the United States
Navy, was appointed by the Bureau of Steam Engineering to
examine the subject; and they conducted a series of tests on
the same plant, and reported them to the Bureau. These trials
were under the active charge of the author. The character of
this work was such as to require from the very first the most
reliable apparatus and the best methods and instruments. In
preparing for it and carrying it on, the author had the best

10 ENGINE TESTS.

opportunity that could be afforded at that time for becoming
educated in the practice of engine-testing, and the training
thus acquired laid the foundation for much of the testing-work
in which he has since been engaged.

This volume relates mainly to the engine tests which the
author has conducted subsequent to the investigations in super-
heating just referred to. It has been his custom, whenever en-
gaged upon any work relating to the performance of engines,
to advocate the determination of their economy on the basis of
feed-water consumption, rather than on that of the coal con-
sumed. Whenever called upon simply for indicating, he has
advocated the feed-water test, rather than to rely solely on the
showing of the diagram. In a great many instances the feed-
water test has thus been undertaken where it would have other-
wise been omitted. By following this practice, and answering
the calls which have come in the ordinary course, the author
has personally obtained a considerable amount of data, which
he believes to be of value to the engineering public, as well as
to all who are interested in the use of power or development of
economical engines, and therefore worthy of publication in
permanent form, as here presented.

The author's work in engine-testing has embraced the indi-
cating of engines for the simple purpose of valve-setting ;
indicating for the determination of the horse-power, or for
determining the power used by various machines or depart-
ments of machinery which the engine drives ; investigations
upon the economy of different systems of operating engines ;
feed-water tests having for an object the improvement of the
engine and the attainment of greater economy ; and tests having
in view the determination of the fulfilment or non-fulfilment of
the terms of a contract guaranteeing a certain efficiency. These
investigations and tests have been made on a great variety of
engines, from the simple non-condensing engine with a single
cylinder, to the triple expansion condensing engine ; and they
relate to many designs and to products of many builders. They
have also covered widely varying conditions of service as to
boiler pressure, cut-off, load, speed, and valve-setting, together

INTRODUCTION. 11

with various conditions in regard to quality of steam, use of
jackets, and the tightness of valves and pistons.

The tests reported in this volume have not been made with
an organized attempt to obtain the performance of certain types
and makes of engines ; but they are the result of the investiga-
tions which the author has made in responding to the calls of
his clients, whether it happened to be for one object or another,
and whatever the class of engine or conditions of service. So
far as given here they are confined mainly to stationary engines
located in manufacturing establishments, and in most cases
operating with a fairly uniform load. Nearly all the tests apply
to engines which have a capacity of at least 100 horse-power,
and they run from this size up to 1700 horse-power.

The first part of the volume is devoted to Feed-Water Tests,
taking up first the simple engine, both condensing and non-
condensing, and afterwards compound, and triple-expansion
engines. The results of the test on each engine are given in a
table by itself, and they .are presented in such detail that all
necessary information regarding the subject is at hand. In
connection with the results is given in each case the dimensions
and such information regarding the design of the engine, the
conditions under which it was worked, and the character of the
test, as is needed for a clear understanding of each case ; and
comments on the results are added where these are required.
In all the engines the condition of the valves and pistons as to
leakage is pointed out so far as this can be expressed in general
terms. The engines selected were, as a rule, fairly tight ; but
in a few cases tests of leaking engines are introduced, either on
account of the general interest attaching to them, or to show
the wasteful effect of the leakage itself in some special instance.
The tables of feed-water tests are followed by a chapter which
presents a general review of the results, showing in brief the
main points of information which the tests bring out. This
chapter takes up the question of cylinder condensation, and
analyzes the tests here reported, with the object of determining
what the percentage of cylinder condensation under different
conditions of running practically amounts to. The relative

12 ENGINE TESTS.

economy of simple, compound, and triple-expansion engines is
considered, also the effects of superheating, jacketing, and piston
speed, so far as the tests furnish data on these subjects.

The chapters on Feed-Water Tests are followed by one de-
voted to Valve-Setting and Effects produced by various condi-
tions of operation, as illustrated by diagrams which the author
has taken in his professional work. The final chapter relates
to Steam-Pipe Diagrams.

In connection with the matter relating to each engine,
whether feed-water tests, valve-setting, or otherwise, sample in-
dicator diagrams are presented, usually reproduced three-fourths
size, showing, so far as possible, average conditions. In the
case of feed- water tests, diagrams are given from both ends of
the cylinders ; but in cases of valve-setting and miscellaneous
diagrams, the diagrams shown are, as a rule, from only one end
of the cylinder.

HOW THE FEED-WATER TESTS WERE
CONDUCTED.

Before presenting the individual feed-water tests, and the
review of the same as noted, it is proper to give a description of
the methods employed in conducting them. This description
is of a general character, applying rather to the usual prac-
tice of the author in conducting these and other engine tests
than to each individual trial reported here. The principles, how-
ever, are applicable to the individual tests quite as much as to
the tests as a whole. In the form thus presented, not only are
the methods employed in conducting these tests described, but
methods which should be adopted in the general work of test-
ing, so far as they accord with the author's experience.

The two essential quantities to be determined in conducting a
feed-water test are the weight of feed-water consumed, and the
indicated horse-power developed in the cylinder.

HOW THE THE TESTS WERE CONDUCTED. 13

MEASUREMENT OF THE FEED-WATER.

How the feed-water should be measured is a matter which
depends somewhat upon the arrangement of the plant and the
type of apparatus used for feeding the boilers, and this must in
a great many cases be adapted to the local conditions. It is
always best to weigh the water, and for this purpose to erect
tanks and scales suitable for the work. There are instances,
however, where it is impossible to do this, because it is neces-
sary that water should be available under some head so as to fill
the weighing-tank, which is generally elevated several feet
above the pump ; and there are cases where no water is at hand
under the necessary head. A meter can be employed in such
cases, or the water may be supplied through an orifice of known
size arranged so as to be calibrated. In most cases, however,
the system of measurement by weighing can be employed ; and
wherever it can be done, the method is to be followed in prefer-
ence to all others. The simplest apparatus of this kind, having
a capacity of say 6,000 Ibs. of water per hour, consists of a
small hogshead connected to the suction-pipe of the pump or
injector, and an ordinary oil-barrel mounted on platform scales,
the latter being supported by the hogshead on one side and by
a suitable staging on the other side. The barrel is filled by
means of a cold-water pipe leading from the source of supply,
and this should be 1-J-" pipe for pressures not less than 25 Ibs.
The outlet valve of the barrel is attached to the side close to
the bottom, and this should be at least 2£" in diameter for quick
emptying. Where larger quantities of water are required, the
barrel can be replaced by a hogshead, and two additional hogs-
heads can be coupled together for the lower reservoir. The
capacity reached by this arrangement when the weighing hogs-
head is supplied through a 2£" valve under 25 Ibs. pressure,
and emptied through a 5" valve, is 15,000 Ibs. of water per
hour. For still larger capacity it is desirable to use rectangular
tanks made for the purpose, and have the weighing-tank arranged
so that the ends overhang the scales and the reservoir below,
the outlet valve, consisting of a flap valve, covering an opening

14 ENGINE TESTS.

in the bottom 6" or 8" square. With rectangular tanks this
system can be employed for any size of stationary engine
ordinarily met with.

Where a meter is used for measurement care should be
observed that water is fed through it at a uniform rate, and the
instrument should be calibrated under conditions in every
respect like those of the test. One method of calibrating. a
meter, which the author has found simple and fairly satisfac-
tory, is to arrange the piping on the outlet side with a valve
known to be tight, and provide, at a point between this valve
and the meter, a tee with a branch having a flexible hose
attached. A gauge is also connected to show the pressure.
The valve leading to the hose need not be of the full size of
the main line ; for under the conditions of the calibration it dis-
charges the water against a pressure much less than the work-
ing pressure, and, if the quantity is small, against practically
no pressure. The hose is carried to two empty barrels located,
preferably, outside of the building, where the water can be dis-
charged without doing harm; and there two workmen are
stationed to manipulate this end of the line. In making the
calibration, the stop valve in the main is closed, and the branch
valve leading to the hose is opened and so adjusted as to keep
the pressure at the working point. The pump or other appara-
tus for feeding is at the same time adjusted to give the working-
quantity of supply. This will be determined by timing the
readings of the meter for, say, one minute. When the proper
rate has been secured, the meter is read ; and at that instant a
signal is given to throw the hose into one of the barrels, the
water during the preliminary operations having run to waste.
When the first barrel is filled, the hose is quickly thrown into
the second one ; and while the second barrel is filling, the work-
men tip the first one over bodily and empty it. When the
second barrel is filled, the hose is quickly transferred back to
the first, and immediately the second barrel is tipped over and
emptied. This can be carried on as long as desired, depending
upon the size of the meter and 'the thoroughness required. The
last reading of the meter is taken when the last barrel becomes

HOW THE TESTS WERE COND UC TED. 15

filled, accurate count having been made of the whole number.
Subsequently the quantity of water contained in the two bar-
rels is ascertained by weighing, and the rating of the meter is
quickly determined by calculation.

When an engine is fitted with a surface condenser, the meas-
urement of the feed-water can be somewhat simplified by col-
lecting the water discharged by the air-pump. In this case the
same kind of apparatus can be used for weighing ; but the two
tanks are reversed, the water being discharged first into the
reservoir, and subsequently drawn into the weighing-tank, which
is placed below it, and, after being measured, thrown away.

An approximate determination of the feed-water consump-
tion can be made by water-glass measurement, assuming that
the type of boiler is such that this method is applicable. The
feed-water is shut off from the boilers for a half hour's time, or
such period as is permissible, and the rate observed at which
the water disappears in the gauge glasses. Subsequently the
volume consumed in the observed time is computed from the
known dimensions of the space occupied, and from this
the weight of the water which has been evaporated. If the
water line is effected to any extent by the condition of the fires,
it is necessary in making these measurements to observe great
care that the conditions of the fires are the same at the end of
such a trial as at the beginning. In some boilers the increased
activity of the fire causes the water line to rise, while the dead-
ening of the fire has the opposite effect. With the damper wide
open, and the fire barred up and in an open or free condition,
there is great activity of the fire ; while with the damper closed
and new coal applied, there is, for the time being, a very marked
reduction in the intensity of the heat. The position of the
damper and the thickness and general characteristics of the fire
should be the same at one time as at the other. It is best to
observe this precaution in all cases, even when there is no sen-
sible effect produced by these changes in the fire. It is also
necessary that the gauge glass and the connections leading from
the water column to the boiler should be clear ; a condition
which can be secured by blowing them out a short time (say

16 ENGINE TESTS.

one hour) previous to the trial. When these are obstructed
a noticeable effect is produced upon the height of water shown
in the glass.

It is also necessary to be assured of the tightness of the feed
valves and check valves concerned, that none of the water
measured escapes by leakage.

The author has, in some instances, been able to obtain a
measurement of the feed-water by drawing it from the tank
which is often provided in mills for fire purposes and other
emergencies, and which is not regularly in use. This tank
being generally of uniform cross-section, the water it contains
is subject to accurate measurement. When such means is used
for measuring feed-water, it is absolutely necessary to be assured
that the water is not in the meantime used elsewhere than for
the test, and that the valves connected with the system of regu-
lar supply do not leak.

The orifice method of measurement is one which the author
has found useful in a number of cases. One instance is that of
a 1000 horse-power compound condensing engine, in which the
water from the hot well was used in the customary manner for
feeding. A test was required to determine the coal consump-
tion of the plant per indicated horse-power per hour, under as
nearly as possible working practice. The quantity of feed-water
used was desired ; but it must be obtained without changing,
any more than necessary, the working conditions. The hot
well overflow pipe was too near the level of the suction pipe of
the pump to permit of using the ordinary process of weighing ;
consequently, resort was had to orifice measurement. The feed-
tank was supplied from the overflow of the hot well through a
4-in. pipe. The elbow on this pipe, next to the tank, was
replaced by a 4-in. tee,, one branch of which looked down and
the other looked up. To the lower branch a pair of flanges
was attached, in which was secured a horizontal plate having a
hole If -in. diameter ; and this served as the orifice. The plate
was horizontal, and the discharge from it was therefore directly
downward into the tank. The upper branch of the tee con-
tained a stand-pipe 3 ft. high ; and to this pipe was attached a

HOW THE TESTS WERE CONDUCTED. 17

glass for showing the height of the water inside, the same being
graduated in inches measured from the face of the orifice plate.
A valve in the 4-in. supply-pipe served to regulate the height of
water in the stand-pipe, and consequently the amount passing
through the orifice. During the progress of the test, the head
of water in the stand-pipe was maintained at such a point as to
supply the required quantity of water; and a careful record
was kept of the height indicated in the gauge glass. Subse-
quently, when the pump was stopped, the orifice was calibrated
by observing the quantity of water which flowed into the tank
under conditions of the average head, the contents being pre-
viously known.

Whatever method is pursued in determining the quantity of
water pumped into the boilers on a feed-water test, a determi-
nation should be made of the leakage of the boilers, stop valves,
safety valves, steam-pipe joints, blow-off cocks, etc., concerned
in the plant, so as to correct for such leakage, and charge the
engine with only that quantity of feed-water which actually
passes into it as steam through the throttle valve. To accom-
plish this object a leakage trial should be made immediately
after the engine is shut down at the close of the test, the
pressure being maintained in the boilers at a point nearly, if
not quite, as high as the working pressure, and no change made
in the stop valves, etc., concerned, or in the drips or other
avenues of escape. Observations should then be made of the
height of water in the gauge glasses, taking readings at inter-
vals of ten minutes for a period of one hour, or until successive
differences in the ten-minute periods show a uniform rate of
leakage. By calculating the weight of water corresponding to
the volume lost, as found by this test, which can be done know-
ing the dimensions of the boilers, the desired correction for
leakage is determined. To make this test reliable it is neces-
sary, of course, that the throttle valve at the engine should be
tight. The tightness of the throttle valve can readily be deter-
mined by observing whether steam blows from the open indi-
cator-cock of the cylinder when the steam valve is wide open,
this observation being made at the end of the cylinder which is

18 ENGINE TESTS.

taking steam. If it leaks, allowance should be made for this
leakage. If there is considerable piping, and it pitches toward
the throttle valve, it is also necessary that allowance be made
for the steam which condenses in the pipes and collects at the
throttle valve. In some cases it will be seen that the condi-
tions may be such that the determination of the correction for
leakage may be a difficult matter; but it is a subject which
ought always to receive attention when the object of the test,
as in the present instances, is to determine the quantity of
steam used by the engine alone.

Whatever method of feed- water measurement is employed, it
is necessary that the height of water in the gauge glass should
be the same at the end of the allotted time of the test as at the
beginning. It is important also that the condition of the fire
should be the same at one time as at the other, because, as
elsewhere noted, the height of the water may be more or less
affected. For example, if the test begins just before firing and
with the damper closed, or nearly closed, it should also end
just before firing and with the damper likewise closed. It is
better to overrun the allotted time or even to cut it short, and
have these conditions right, than to overlook them in the desire
to make the duration of the trial a predetermined number of
hours to the exact minute. If the height of the water at the
end of the test is different from what it was at the beginning,
the necessary correction estimated from the corresponding vol-
ume of water is applied to the quantity weighed. This correc-
tion is determined with sufficient accuracy, in most cases, by
calculation from the known exterior measurements of the boiler.

INDICATING.

It is unnecessary for the purposes of this volume to go into
a description of steam-engine indicators, for the books on the
subject of the indicator furnish an ample amount of informa-
tion of this character. It will suffice to say that for most of
the tests here reported the instruments used were either of the
Tabor or the Crosby pattern, or both. The methods of apply-
ing the instruments, however, the means of driving them and

BOW THE TESTS WERE CONDUCTED. 19

manner of using them, also the methods employed in calibrating
the springs, require notice.

In nearly all the indicator work on the Corliss, and similar
types of slow-speed engines, the driving-rig has been some
form of pantagraph, and in the large majority of cases, that
form known as the "lazy-tongs," working horizontally and
operated from the cross-head. The fixed end of the lazy-tongs
has generally been applied to one of two wooden posts, attached
to a base-board, which in turn is fastened to the floor. The
second post, suitably located with reference to the first, is used
for the support of a carrier-pulley, and both posts are securely
fixed in position by means of three wooden braces fastened to
the floor. This method of attaching the lazy-tongs has the
advantage of rigidity, which is so essential to a correctly driven
indicator; and the use of the carrier-pulley enables the driving-
cord to be always led off in a line parallel to the direction of
motion of the cross-head, whatever the position of the indi-
cators with reference to the cord-pin of the lazy-tongs. The
construction of a stand for supporting the lazy-tongs in this
manner may be considered crude and clumsy for permanent
use ; but the author has often found permanent rigs defective
from improper design or insecurity, due to gradual wear, and
substituted the one described. Being made throughout of
wood, it is a device which can be quickly put together, even
where there is no carpenter-shop at hand and little material.
As it is built in such form as to easily and positively accom-
plish the desired ends, it has been found most useful.

For a driving-cord, a strong braided linen fish-line having an
unbraided core is used, extending a little beyond the carrier-
pulley ; and from this point to the indicators, pieces of annealed
brass wire are used, about No. 25 B.W.G. (3y in diameter).
For a single cylinder two cords are thus brought into use lead-
ing from the same initial point. In the case of tandem cylin-
ders, either four independent cords are used, or two independent
cords, each having branch loops at appropriate points for con-
necting to the two instruments. In some cases the cords have
been displaced by a light wooden rod driven by the cord pin of

20 ENGINE TESTS.

the lazy-tongs, and moving on guides attached to the cylinder,
the direction of motion being parallel to it. A screw fastened
to the rod at the proper place serves to carry the motion to the
cord attached to the indicator. The use of the rod in place of
the cords is especially applicable to tandem engines.

For high-speed engines the driving apparatus is some form
of lever and sector, the shaft on which the lever is mounted
being in many cases supported by a stand bolted to the frame
of the engine. In some engines of the high-speed compound
class the driving motion is derived from an eccentric fastened
to the main shaft, the motion being carried from this point to
the cylinder through a connecting-rod and bell-crank lever. In
these cases an independent motion is used for each cylinder.

It has been the custom in making these tests to employ two
indicators for each cylinder, attached as close as possible to the
end of the cylinder, using the half-inch connection, a right-angle
elbow, and the indicator-cock furnished with the instrument.
Sometimes a straight-way valve is placed below the indicator-
cock for facility in moving the same without shutting down
the engine. The objections to long pipes connected by a three-
way cock in the center, consist in the increased friction of the
steam in passing through the greater length of the pipe with
the increased number of bends, and in the collection of water
in the long horizontal cavity which is thus brought into play.
If two indicators are not available for an engine test, it seems
better to use one instrument, and transfer it from one end to
the other, than to employ the three-way cock and have the
instrument fixed at the central point with the long connections.

On many of these tests " prepared " indicator paper has been
used, the instrument being fitted with metallic marking-points.
These marking-points are made of brass wire of suitable size,
which is- reduced in diameter near the marking end to about
sV, so that by the use of a small hand-vise, such as watch-
makers employ, and an oil-stone, the marking-point is readily
kept in shape for tracing fine lines. The use of metallic paper
is much to be preferred, as a matter of convenience, to plain
sheets with the ordinary lead-pencil point, inasmuch as the

HOW THE TESTS WERE CONDUCTED. 21

sharpening of the metal point requires much the less atten-
tion.

The driving mechanism for the work referred to here has in
110 case been any form of reducing-wheel.

GENERAL METHOD OF CARRYING ON THE
FEED-WATER TEST.

The testing apparatus being in readiness, and the engine
working with the desired load, the height of water in the
gauge glasses is observed, the time taken, and the position of
the water in the reservoir of the weighing apparatus observed.
Thereafter all the water fed is weighed. At the expiration of
the time determined upon, the water in the gauge glasses and
in the lower reservoir is brought to the starting-point, and the
exact time observed. During the progress of the test indicator
diagrams are taken every thirty minutes, and sometimes every
twenty minutes, and at the same time the gauges are observed
and the number of revolutions per minute counted. If the
steam is superheated, the temperature of the steam is observed ;
and if calorimeter tests are made, these are either continuous
or made at convenient intervals. Where special accuracy is
required, the atmospheric pressure is determined by observa-
tion of a barometer at some time during the progress of the
test. For this, it is sufficient for all practical purposes to rely
upon the record of the United States signal service at the
nearest station. When the test is made in a factory running
ten hours per day, say five hours in the forenoon and five hours
in the afternoon, the record in some instances embraces the
whole period from the time the engine starts until the time of
stopping. In that case the initial and final readings of the
water glasses are taken just before the engine starts, and just
after it stops. The duration is taken from the time the engine
attains its working speed till the time the throttle valve is
closed ; and no further account is taken of the power devel-
oped while the engine is reaching its speed after first
starting. In that case, the first set of diagrams is taken not
less than five minutes after the load is put on ; and the as-

22 ENGINE TESTS.

sumption is made that the loss of steam from condensation and
drips during the time the engine is first starting and attaining
its working speed counterbalances the deficiency of load be-
tween the time when the speed is attained and the working-
load is actually applied. In factory work, the interval of time
between the attainment of the working speed and the applica-
tion of the full load is usually less than three minutes.

In taking diagrams from an engine with the object of deter-
mining its power, it is not desirable to limit the diagram to a
single revolution. The marking-point of the indicator should
be applied long enough to obtain four or five diagrams, cor-
responding to that number of successive revolutions, in order
that the effect which the fluctuations in the governing mechan-
ism has upon the diagrams may be provided for. In working
up the diagrams, then, the mean pressure is obtained for the
average diagram, and not for any single one. By pursuing
this method, the average power which is determined relates to
several times as many diagrams as it would if it were confined
to a single revolution in each case. Instances are frequently
met where the fluctuations in the cut-off for half a dozen suc-
cessive diagrams varies from 2 to 5 per cent of the length of
the stroke, and in such cases this matter is of considerable im-
portance. As a convenience in working up the diagrams, a
good plan to follow is to go over each one with a pencil, and
trace with dotted lines the diagram which represents an aver-
age of those made by the indicator, and in the subsequent
calculations to use this dotted diagram. When a load is ex-
tremely fluctuating, this system should be carried further. The
period of taking the diagram should extend over at least a full
minute, though it is unnecessary to make it a continuous dia-
gram for this length of time. The marking-point can be pre-
ferably applied for three or four revolutions at the beginning
of, say every ten seconds of a minute, and in that way the
record applies to some twenty revolutions spread over the full
period. Having these diagrams now on the same card, an
average line can be dotted in by hand, using the best judgment
after examining the appearance of the various diagrams and
their location.

HOW THE TESTS WERE CONDUCTED. 23

The same method is usefully applied in tests of electric rail-
way engines. Indeed, except by some system of this kind, no
fair idea of the indicated horse-power can be obtained, and no
good comparison can be made between the indicated horse-power
and the electrical horse-power. In these engines it is best to
make the interval between the sets of diagrams thus obtained
not more than ten or fifteen minutes. It should be arranged
to give a signal every ten seconds while the operation is going
on, so that all the indicators may be worked together for the
three or four revolutions desired. Likewise, on the same signal
corresponding readings are taken of the electrical instruments.
This is continued until the period of time covered is two or
more minutes. The diagrams being all taken on the same card,
without unhooking the indicators, the means is at hand for ob-
taining an average for the whole period, as before pointed out.

LEAKAGE TESTS OF VALVES AND PISTONS.

The determination of the condition of an engine as to the
tightness of the valves and pistons has nothing to do with the
work of making a feed-water test, or of correctly ascertaining
the results. When, however, it comes to analyzing the results,
and ascertaining whether the engine is working with a proper
degree of economy, and if not, the reasons for the waste, it is
of the utmost importance that the matter of leakage should be
investigated. It is always desirable, therefore, when a feed-
water test is conducted, to supplement it by an inspection of the
valves and pistons having this object in view. This inspection
must be made when the engine is at rest. The conditions
which surround the internal working parts of an engine at rest
are entirely different from those of the engine in motion, and
for this reason it is held by some that an examination of leak-
age under these circumstances gives little information which
can be applied to working conditions. Those who take this
view hold that under conditions of motion the quantity of leak-
age is reduced, and it might happen that the leakage in motion
would be altogether insignificant, although very serious at rest.
The author takes the ground that the only course open in this

24 ENGINE TESTS.

matter is to make the examination when the engine is at rest,
for certainly no thorough inspection can be made when it is in
motion. If it is found that there is practically no leakage at
rest, it seems reasonable to conclude that the engine is tight in
motion. If, however, there is leakage at rest, we can certainly
say that there is a probability of leakage in motion, although it
may not be possible to judge of its degree.

The leakage tests here referred to are not quantitative ; that
is, they do not determine the exact amount of leakage, but
rather the fact as to whether leakage does or does not exist.
They are intended simply to give the observer a fair idea as to
the general condition of the engine.

Turning to the methods employed in testing for leakage, the
steam-valves are readily disposed of. In a Corliss engine, it is
necessary simply to close the two admission valves, open the
two indicator-cocks, and with the starting-bar move the exhaust
valves first one way and then the other, the throttle valve be-
ing open, and a full pressure of steam being admitted into the
chest. When the starting-bar is moved so as to close the ex-
haust valve at the head of the cylinder, any leakage of steam
through the steam valve at that end will be made to escape at
the indicator-cock, and thus become visible. Likewise when
the starting-bar is moved so as to close the exhaust valve at the
crank end, the steam which leaks through the crank-end ad-
mission valve will show itself at the open cock. In making
these movements of the starting-bar, care is taken that the
steam valves are held unhooked. The quantity of leakage is
judged by the force of the current of steam blowing out of the
cock. If the valves are tight there is simply a breath of steam,
or an entire absence of vapor. If they leak badly, the cur-
rent will blow out of the indicator-cock with much force and
noise, and rise to a height of several feet.

In testing the exhaust valves and pistons for leakage, the
best method is to block the fly-wheel in such a position that the
engine is taking steam with the piston at a short distance from
the end of the stroke, open the throttle valve, and observe what
blows through. It is well to try this if possible with the

HOW THE TESTS WERE CONDUCTED. 25

piston at different points. If the end of the exhaust pipe is
open to view, as would be the case with a non-condensing
engine, the steam which leaks through can be observed at the
open outlet. This can also be done in the case of a condensing
engine where there is a branch exhaust pipe leading to the at-
mosphere. Where the engine is condensing, and no such branch
is provided, and there is no other opening in the exhaust pipe
in front of the condenser, a pretty good idea can be obtained of
the general facts by observing the amount which the condenser
is heated by the steam which leaks.

With the piston in any given position in a Corliss engine,
the leakage on such tests embraces the leakage of one exhaust
valve, one steam valve, and the piston. To investigate the
leakage of the other steam valve and the other exhaust valve,
the test must be made with the piston taking steam on the
opposite stroke. In either case, if the previous inspection of
the two steam valves shows them to be leaking, this fact must
be considered in drawing conclusions as to the leakage of the
piston and exhaust valves.

There is another method of testing the leakage of piston and
exhaust valves, namely, the " time method." The fly-wheel is
blocked, as before, with the piston at some distance from the
beginning of the stroke, the throttle valve is opened, and steam
is admitted at full pressure until the cylinder is thoroughly
warmed. Then the throttle valve is shut, and the length of
time is observed which is required for the steam to escape
through the leaking openings. To conduct the test properly,
an indicator is attached to the cylinder at the end containing
the steam, and a mark is made on a blank card at intervals of,
say, one-quarter of a minute from the time the throttle valve is
closed ; and by this means the rate of fall of pressure and escape
of steam is recorded. This test, like the others, is qualitative,
and not quantitative. The relative condition of the engine
determined from results of the time tests must be judged by
comparing with other cases where known conditions of excel-
lence prevailed. In a leaking engine the fall of pressure on a
test of this kind is very rapid. If the leakage is serious, the

26 ENGINE TESTS.

first observation, after a quarter minute interval, might show a
reduction of pressure covering nearly the whole range down to
the atmosphere. On the contrary, if the engine is tight, the
reduction of pressure to the atmosphere would require from
five to ten minutes time. The author finds that the pressure
will not fall as a rule more than fifty per cent at the expiration
of one minute from the time of shutting the throttle valve, if
the engine is fairly tight.

If, on leakage tests with the blocked engine, it is found that
the piston and the two valves leak, whichever stroke the piston
is occupying, the piston leakage can be eliminated by discon-
necting the valve rods in such a way as to open both steam
valves and close both exhaust valves. When this is done, the
resulting leakage which is observed applies to the exhaust
valves alone.

The leakage of a piston can always be inspected by removing
the cylinder head and applying a pressure behind the piston.
The leakage then appears at the open end of the cylinder. On
large engines the operation of taking off a cylinder head is
attended with considerable labor. The methods which have
been described can be brought into use with great facility and
save this labor, to say nothing of saving time.

The blocking of the engine which these tests require is a
thing which should not be undertaken in any careless manner.
In most cases the masonry foundation of the engine is so
arranged that a piece of timber can be placed between the
spokes of the wheel, and the two ends laid upon or against the
foundation, the strain of a spoke being brought to bear upon
the middle of the timber. This timber should be of ample size,
say, a 12 in. or 14 in. stick of hard pine for an engine of 1000
horse-power, the points of support at the two ends being not
over 8 ft. apart. The position of the arm should be brought as
nearly as possible to the proper point before the block is intro-
duced, the leeway being filled in not by subsequently moving
the engine, but by the introduction of wooden filling-pieces and
wedges. In the case of an engine having a shaft with two
cranks and a solid bed beneath each one, the engine can be

HOW THE TESTS WERE CONDUCTED. 27

readily blocked in certain positions by standing a piece of tim-
ber endwise, reaching from the end of the crank to the floor
or bed, or by putting in a nnmber of wooden blocks laid flat,
and building up to the desired height. Here, again, the crank-
pin should be brought to the required position before the blocks
are put in, and filling-pieces should be applied to make up the
leeway, rather than move the engine and run the risk of injury
by bringing up solid against the blocks.

Leakage tests of the valve in the case of single-valve engines
cannot be made as satisfactorily as those in four-valve engines,
for if the valve leaks excessively it is difficult to locate by these
methods the exact place of the leak. The best that can be
done is to place the valve on its center covering both ports,
and try it under a full steam pressure. The same course can
be followed in testing the piston as that described for the four-
valve engines. In a leaking engine of this type, it is usually
necessary to test the piston with the cylinder head removed
before the investigation is complete.

It is needless to call attention, in more than a passing way,
to the test of piston leakage in an engine which is single-acting.
In a Westinghouse engine, for example, the leakage of the
piston is revealed by simply swinging off the cover of the crank
case, and observing at once what escapes from the periphery
of the piston, the engine being blocked and stearii pressure
admitted into the cylinder.

The foregoing remarks on the subject of leakage apply to
simple engines. In the case of compound engines the work is
to some extent simplified. For example, in testing the leakage
of the high-pressure exhaust valves and piston, the escape of
steam is observed by opening the indicator-cock on the end of
the low-pressure cylinder which is taking steam, and observ-
ing what blows through. Again, in testing the low-pressure
exhaust valves and piston by the time method, steam is ad-
mitted into the receiver until the desired pressure is reached,
then, after the cylinder has been thoroughly warmed, and the
supply shut oft, the drop in pressure is observed by reading the
receiver gauge and keeping a record of this. A similar course
is followed in testing the leakage of triple-expansion engines.

28 ENGINE TESTS.

CALIBRATION OF INSTRUMENTS.

For a satisfactory comparison of the steam-pipe gauge with
the initial pressure shown by the diagram, the best plan is to
compare the gauge and the indicator without changing them
from their working positions. This can be done at the same
time that the leakage tests are in progress, as, for example,
when testing the piston and exhaust valves, the fly-wheel being
blocked, and the throttle valve and admission valve set wide
open. By taking the reading of the steam gauge and that of
the indicator at the same time (the latter being done by open-
ing the indicator-cock, then drawing a short line on the blank
card which has been applied for the purpose), not only will the
error of the gauge itself be allowed for, but also the error pro-
duced by the head of water contained in the gauge pipe, if any
such error exists. This comparison alone is sufficient to estab-
lish the difference in pressure between that in the main pipe
(or in the boiler to which the gauge is attached) and the
initial pressure in the cylinder of the working-engine, whether
the gauge, or indicator, or both, are in themselves correct or in
error. The gauge is then calibrated by reference to a standard,
and the accuracy of the indicator is established at the particular
pressure used. This single calibration is considered in many
cases sufficient for determining the correct scale of the indicator
in question. (

The most satisfactory method of determining the correctness
of the gauge, is to remove it from its place, and attach it to a
dead weight testing-apparatus, of the form sold by the steam-
gauge manufacturers, in which the pressure is produced by
sealed weights resting upon the top of a vertical plunger of
known area, the pressure being transmitted to the gauge
through the medium of oil or glycerine. The convenience of
this method and the portability of the apparatus, together with
its extreme reliability, place it ahead of all other systems for
calibrating gauges. Having made the calibration, the indica-
tion of the gauge in its working position must be corrected for
the head of water in the supply-pipe of the gauge, if any exists,
whether it be to increase the indication or to reduce it.

HOW THE TESTS WERE CONDUCTED. 29

The calibration of the indicator springs used on the tests
reported in this volume has in many cases been carried on by
testing them under the action of dead weights, and correcting
the result thus found by a percentage of allowance for the
reduced tension caused by the heat of the steam in which they
ordinarily work. The author's testing-apparatus consists of a
scale-beam mounted on knife edges, on one end of which the
weights are suspended. The movement of the beam at the
other end is transmitted upward by means of a vertical adjust-
able rod extending to the under side of the indicator piston.
The tests are made with the highest pressure to which the
springs are subjected, and from this point down to the atmos-
phere at uniform reductions. The apparatus is operated so as
to get an average reading, whether the pressure is going up or
going down. This is done each time by pushing the scale-beam
down as far as it will go, and drawing a line on the indicator-
card, then, without changing the weight, pushing the same
upward as far as it will go, and marking another line. When
the lines are measured, the mean of the two is selected as the
true indication. The springs are in some cases compared under
different pressures with a correct steam gauge, admitting the
steam directly into the indicator, and subjecting it as near as
possible to its working conditions of temperature. In making
calibrations under steam, difficulties are often experienced in
obtaining satisfactory indications, owing to the friction of the
piston of the indicator under the action of the continuously
applied pressure. This is overcome, provided the pressure is
maintained at a constant point, by drawing two lines with the
instrument, one when the pencil-arm is pushed down with the
finger as far as it will go, and the second when the arm is
pushed up as far as it will go, the true indication then being
taken as the mean of the two. When a set of indicator springs
has once been calibrated, and their exact scales obtained, the
dead-weight apparatus above referred to furnishes a much more
satisfactory means for future determinations, and for showing
the changes in the scale which may take place under continued
use, than the steam-testing apparatus, for the reason of its

30 ENGINE TESTS.

greater simplicity and ease of operation, together with its free-
dom from the particular errors noted.

In calibrating the springs for pressures below the atmosphere,
the dead-weight apparatus referred to is not applicable, and
resort has been had in these tests to comparison with a mercury
gauge, or with a standard vacuum gauge, the former being pre-
ferred. In making these comparisons in the shop or laboratory
it is necessary to obtain a vacuum by the use of some form of
pump or exhauster, and this often proves an inconvenience.
For this reason the author has been in the habit of making
them in the engine room where the indicators are being used,
and where a vacuum is obtained by connecting the testing-
apparatus with the condenser. All that is required for ap-
paratus is the connection to the condenser, a tee for the
attachment of the indicator-cock, and a mercury gauge applied
to one end of the tee. With this apparatus the spring can be
calibrated down to the lowest pressure to which it is subjected.
It is desirable to make the calibration of an indicator spring
that is used for pressures below the atmosphere under condi-
tions of vacuum as well as under conditions of pressure; for the
fact that the spring is correct when subjected to compression, as
it is when a pressure is applied to it, furnishes no positive
assurance that it is correct under tension, as it is when it is
subjected to a vacuum.

It is of no little importance that the scale of the spring
should be known within reasonable limits of error; for upon
this knowledge depends the whole accuracy of the indicator
work, and consequently of all the results of the tests depending
upon it.

MANNER OF WORKING UP THE TESTS.

The results of the feed-water tests are computed from the
hourly consumption of feed-water corrected for the leakage of
the boilers, pipes, and connections, as explained, and the indi-
cated horse-power developed. The " steam accounted for by
the indicator " is determined from measurements of the dia-
grams and computations based thereon.

HOW THE TESTS WERE CONDUCTED. 31

The indicator cards relating to the tests reported here have,
as a rule, been measured by a polar planimeter. The average
obtained by going over the line of the diagram at least twice is
the reading taken.

The mean effective pressure is determined by dividing the
scale of the spring by the length of the diagram expressed
in inches and decimals of an inch, and multiplying the quo-
tient by the area in square inches. The length of the dia-
grams, which is nearly constant, is found by selecting, say three
sets out of every ten taken on the test, and obtaining the
average length from those three. The horse-power is computed
by multiplying the "horse-power constant" for the cylinder
under consideration by the speed in revolutions per minute, and
by the mean effective pressure. The horse-power constant is
the power developed in the cylinder, assuming one pound mean
effective pressure and a speed of one revolution per minute.
It is obtained by multiplying the mean of the areas of the two
sides of the piston in square inches by twice the length of the
stroke in feet, and dividing the product by 33,000. The mean
effective pressure used is the mean of the two measurements
obtained at the two ends of the cylinder. In the detail tables,
giving the data and the results of the tests here reported, the
horse-power constant for each cylinder is given ; and the figures
of indicated horse-power in any case are the result of multipli-
cation of this constant, the revolutions given per minute, and
the mean effective pressure. For example, in the case of
Engine No. 1, which has a single cylinder 23" diameter, 5'
stroke, with one piston-rod 3^'7 in diameter, the horse-power
constant is .1247, the speed 74.7 r.p.m., and the m.e.p. 33.08
Ibs. The indicated horse-power, viz., 305.2, is the product of
these three quantities.

The water per indicated horse-power per hour is found by
simply dividing the hourly consumption of water by the indi-
cated horse-power. In the example referred to, the hourly con-
sumption being 8477 Ibs., the feed-water per I.H.P. per hour is
8477 divided by 305.2 equals 27.77 Ibs.

The method of determining the quantity of steam " accounted

32 ENGINE TESTS.

for by the indicator" consists -in measuring the diagrams for
the necessary data, and using the formula

i^° [(c + e) Wx - (h + e) Wh]
m.e.p. L

in which " m.e.p." is the mean effective pressure measured from
the diagrams as pointed out ; " c " the proportion of the forward
stroke completed either at cut-off or release, according as the
determination is made at one point or another ; " h " the pro-
portion of the return stroke uncompleted at compression ; " e "
the proportion of the clearance space ; " Wx " the weight of one
cubic foot of steam at the cut-off or release pressure ; and
" Wh " the weight of one cubic foot of steam at the compres-
sion pressure.

The points on the diagram where these measurements are
taken are illustrated in the sample diagram Fig. 1 given below.
These points are located as follows : The point of cut-off is
marked at the beginning of the expansion line after the steam
valve has completely closed. It is at the point where the curve
changes its direction from that due to the gradually closing
steam valve to that of the expansion line. The point of re-
lease is marked at the end of the expansion line just before
the curve begins to drop, due to the opening of the exhaust
valve. Likewise the compression point is fixed at the begin-
ning of the true compression line, or at the end of the curve
formed by the gradually closing exhaust valve. The principle
followed is to locate the points of cut-off and release so as to
account for all the steam present in the cylinder at the instant
the steam valve is closed, and for all the expanded steam
present just before the exhaust valve opens. The compression
point is located with the idea of obtaining a measurement of
all the exhaust steam which is retained in the cylinder at the
moment the exhaust valve is closed.

In all these tests the computations are made both at the cut-
off point and the release point. It is desirable to do this, be-
cause there is often a considerable difference between the two
quantities ; and where there is such a difference, much more can

HOW THE TESTS WERE CONDUCTED. 33

be learned from the examination of the steam accounted for at
cut-off than that accounted for at release. The difference in
the work done during expansion is not proportional to the dif-
ference in the steam accounted for; and, consequently, the
actual loss of economy due to cylinder condensation and leak-
age is more closely measured by the percentage which is
accounted for at cut-off than by the percentage accounted for
at release. Between the two, if only one computation is to be
made, it is better to use the cut-off point than the release point.

Fig. 1.

The proportions uc" and "h" are found by measuring the en-
tire length of the diagram, first erecting perpendiculars at the
extreme points, and then measuring the length up to the point
marked, dividing one by the other, and ascertaining the result-
ing proportion expressed in a decimal. The proportion " e " for
the clearance may be found either by measurement of the
clearance spaces from drawings of the cylinder and valves or
from actual test. The latter is to be preferred ; for drawings,
however correct in themselves, do not show the exact measure-
ments of the material, especially of the ports and passages
which are in the state of rough casting.

To measure the clearance by actual test, the engine is carefully
set on the centre, with the piston at the end where the measure-
ment is to be taken. Assuming, for example, a Corliss engine,
the best method to pursue is to remove the steam-valve so as
to have access to the whole steam-port, and then fill up the

34 ENGINE TESTS.

clearance space with water which is poured into the open port
through a funnel. The water is drawn from a receptacle contain-
ing a sufficient quantity, and this has previously been measured.
When the whole space, including the port, is completely filled,
the quantity left is measured, and the difference shows the
amount that has been poured in. The measurement can be
most easily made by weighing the water, arid the corresponding
volume determined by calculation. The proportion required in
the formula is the volume in cubic inches thus found, divided
by the volume of the piston displacement, also in cubic inches,
and the result expressed as a decimal.

The only difficulty which arises in measuring the clearance
in this way is that occurring when the exhaust valve and
piston are not tight, so that, as the water is poured in, it flows
away and is lost. If the leakage is serious, no satisfactory
measurement can be made, and it is better to depend upon the
volume calculated from the drawing. If not too serious, how-
ever, an allowance can be made by carefully observing the
length of time consumed in pouring in the water; then, after
a portion of the water has leaked out, fill up the space again,
taking the time and measuring the quantity thus added, deter-
mining in this way the rate at which the leakage occurs. Data
will thus be obtained for the desired correction.

In the tests here reported the clearance has not, as a rule,
been determined by actual measurement in the manner noted,
nor even in all cases by the calculation from the drawing. In
cases where the proportion of clearance is assumed, the assump-
tion is based on the known clearance of similar classes of engines,
determined either by water measurement or calculation. The
effect which a small error in the clearance may have upon the
result of the computation of steam accounted for is not of a
serious nature, unless it is a case where the cut-off is very short.
For example, if the steam accounted for with a clearance of five
per cent comes out TW of the feed-water consumption, the re-
sult with a clearance of 4 % would be T7o3<j, changing the pro-
portion about T§Q at cut-off and much less at release.

In compound and other multiple expansion engines the same

HOW THE TESTS WERE CONDUCTED. 35

formula for determining the steam accounted for by the indica-
tor is used as that given above, but it must be adapted to the
type of engine. The only change required in the formula is
in the mean effective pressure. Here the quantity used when
determining the steam accounted for in any given cylinder is
the collective mean effective pressure cf all the cylinders
assumed to be referred to the one under consideration. In the
case of the high-pressure cylinder of a compound engine the
quantity to be used is the sum of the mean effective of the H. P.
cylinder and a quantity representing the m.e.p. of the low-pres-
sure cylinder referred to the high-pressure cylinder; that is, the
mean effective pressure in the low-pressure cylinder multiplied
by the ratio of the volume of the L. P. cylinder to the H. P.
cylinder. If the ratio is 4 to 1, the m.e.p. of the low-pressure
cylinder is to be multiplied by four to determine the quantity
desired. Likewise the quantity to be used for computing the
steam accounted for in the low-pressure cylinder is the sum of
the mean effective pressure in that cylinder, and the mean effec-
tive pressure in the H. P. cylinder divided by the ratio of the
volume of the L. P. cylinder to the H. P. cylinder. In the
instance given it would be the mean effective in the H. P.
cylinder divided by 4. In a triple expansion engine the mean
effective pressure to be used for computing the steam accounted
for in the L. P. cylinder is the sum of the mean effective pres-
sure of that cylinder ; that of the m. e. p. of the H. P. cylinder
divided by the ratio of volume of the L. P. cylinder to that of
the H. P. cylinder, and the m.e.p. of the intermediate cylinder
divided by the ratio of the volume of the L. P. cylinder to that
of the intermediate cylinder. Likewise the quantity to be used
for the intermediate cylinder is the sum of three quantities,
namely, the m.e.p. of the intermediate cylinder, the m.e.p. of
the H. P. cylinder divided by the ratio of the volume of the
intermediate cylinder to that of the H. P. cylinder, and the
m.e.p. of the L. P. cylinder multiplied by the ratio of the volume
of the L. P. cylinder to that of the intermediate cylinder.

As an example of the proper method of computing the equiv-
alent mean effective pressure referred to either cylinder of a

36 ENGINE TESTS.

compound engine, we may take the case of Engine No. 32, in
which the ratio of volumes of the cylinders is as 1 to 3.43, and
the mean effective pressure in the two cylinders 41.26 Ibs. and
9.28 Ibs. respectively. The equivalent m.e.p. to be used in
computing the steam accounted for in the H. P. cylinder is
46.26 + (9.28 x 3.43) = 41.26 + 31.83 = 73.09. For the low-

A ~f O£?

pressure cylinder the quantity is 9.28 X ' = 9.28 + 12.03
= 21.31.

As an example of this method applied to a triple expansion
engine we may take the case of Engine No. 59, in which the
ratios of volumes are as 1 to 2.94 to 6.5, and the mean effec-
tive pressures, 60.56 Ibs., 13.22 Ibs., and 10.16 Ibs. respectively.
The quantity to be used for the H. P. cylinder is 60.56 +
(13.22 x 2.94) + (10.16 x 6.05) = 60.56 + 38.87 + 66.04 =
165.47. The quantity for the intermediate cylinder is 13.22 Ibs.

+ T5T + (10'16 x ^5i> = 20'6 + 13'22 + 22'46 = 56'28'

For the low-pressure cylinder the quantity is 10.16 + (13.22 x

^± ) + ^ = 9.82 +5.98+ 10.16 = 25.46.
b.o o.o

The weights of steam per cubic foot used in the formulae for
determining the steam accounted for in the tests under con-
sideration are those deduced from Regnault's experiments as
given in D. K. Clark's Manual.

The following examples will serve to illustrate the use of
the formulae, one case being a single expansion engine and the
other a triple expansion.

Engine No. 22, Simple Condensing Engine.

Clearance ,....; •*..'-: .. ; , ..- . .' ,......« 2%

Cut-off pressure above zero . . •„ ~. .' . 75.6 Ibs.

Weight per cubic foot at cut-off pressure \ / . . . ... .1773

Release pressure . . . ^ " .' ... . 15.5

Weight per cubic foot at release pressure . .0399

Mean effective pressure ". 37.17

Compression pressure 3

Weight per cubic foot at compression pressure .0085

HOW THE TESTS WERE CONDUCTED. 37

Proportion of direct stroke completed at cut-off ...... .172

Ditto at release ............... . . .903

Proportion of return stroke uncompleted at compression . . . .048

The steam accounted for at cut-off is »t [(.172 + .02)

37.17

x .1773 - (.048 +.02) x .0085] = 369.9 x (.03404 - .00056)
= 369.9 x .03348 = 12.39. The steam accounted for at release

is 18'750 f (.903 + .02) x .0399 - (.048 + .02) x .0085 =
37.17

369.9 (.03682 - .00056) = 369.9 x .03626 = 13.41.

Engine No. 59— Triple Expansion.

H. P. Cylinder at Cut-off.

Clearance 2.5 %

Cut-off pressure 145.2 Ibs.

Weight per cubic foot at cut-off pressure .3277 "

Compression pressure 46.8 "

Weight per cubic foot at compression pressure .1129 "

Mean effective pressure 60.56 "

M. E. P. of all the cylinders, referred to H. P. cylinder . . . 165.47 "

Proportion of direct stroke completed at cut-off .346

Proportion of return stroke uncompleted at compression . . . .006

The steam accounted for at cut-off is I" * [ (.346 + .025)

loo. 47

x .3277 - (.006 + .025) x .1129] = 83.1 x (.1216 - .0035)
= 83.1 x .1181 = 9.81.

Intermediate Cylinder at Cut-off.

Clearance 2.5 %

Cut-off pressure 38.7 Ibs.

Weight per cubic foot at cut-off pressure ........ .0945 "

Mean effective pressure 13.22 "

M. E. P. of all the cylinders, referred to the intermediate cylinder, 56.28 "

Compression pressure 20.7 "

Weight per cubic foot at compression pressure .0524 u

Proportion of stroke completed at cut-off .406

Proportion of return stroke uncompleted at compression . . . .008

38 ENGINE TESTS.

The steam accounted for at cut-off is, -=-^- — X [ (.406 +

5b.28

.025) x .0945 - (.008 + .025) x .0524] = 244.3 x (.0407 -
.0017) = 244.3 x .039 - 9.53.

L. P. Cylinder at Cut-off.

Clearance 2.5 %

Cut-off pressure 16.0 Ibs.

Weight per cubic foot at cut-off pressure . .0411 "

Mean effective pressure 10.16 " "

M. E. P. of all the cylinders, referred to L. P. cylinder . . . 25.46 "

Compression pressure 2.3 "

Weight per cubic foot at compression pressure .0066 "

Proportion of stroke completed at cut-off .357

Proportion of return stroke uncompleted at compression ... 0

The steam accounted for at cut-off is, — ' — - [ (.357 + .025)

x .0411 -- (.025 x .0066) ] = 540.1 x (.0157 -- .00017) =
540.1 x .01553 = 8.39.

It is unnecessary to give the computations for the release
points of these diagrams, the method being illustrated in the
example given above for Engine No. 22.

13 750

The following table gives the quantity - for mean

effective pressures running from 10 to 100, advancing by two-
tenths of a pound; and from 100 to 200 advancing by pounds.

HOW THE TESTS WERE CONDUCTED.

13750

39

Table of

M. E. P.

M. E.P.

13750

M. E.P.

13750

M. E. P.

13750

M.E . P.

13750

M.E. P.

M. E. P.

M.E. P.

M.E. P.

10.0

1375.0

20.0

687.5

30.0

458.3

40.0

343.8

.2

1348.

.2

680.7

.2

455.3

_2

342.0

.4

1322.1

.4

674.0

.4

452.3

.4

340.3

.6

1297.1

.6

667.5

.6

449.3.

.6

338.7

.8

1273.1

.8

661.1

.8

446.4

.8

337.

11.0

1250.

21.0

654.8

31.0

443.5

41.0

335.3

.2

1227.7

.2

648.6

.2

440.7

.2

333.7

.4

1206.1

.4

642.5

.4

437.9

.4

332.1

.6

1185.4

.6

636.6

.6

435.1

.6

330.5

.8

1165.3

.8

630.7

.8

432.4

.8

328.9

12.0

1145.8

22.0

625.0

32.0

429.7

42.0

327.4

.2

1127.1

.2

619.4

.2

427.

.2

325.8

.4

1108.9

.4

613.8

.4

424.4

.4

324.3

.6

1091.3

.6

608.4

.6

421.8

.6

322.8

.8

1074,2

.8

603.1

8

419.2

.8

321.3

13.0

1057.7

23.0

597.8

33.0

416.7

43.0

319.8

.2

1041.7

2

592.7

.2

414.1

.2

318.3

.4

1026.1

A

587.6

.4

411.7

.4

315.8

.6

1011.

.6

582.6

.6

4092

.6

315.4

.8

996.4

.8

577.7

.8

406.8

.8

313.9

14.0

982.1

24.0

572.9

34.0

404.4

44.0

312.5

.2

968.3

.2

568.2

.2

402.

.2

311.1

.4

954.9

.4

563.5

.4

399.7

.4

309.7

.6

941.8

.6

558.9

.6

397.4

.6

308.3

.8

929.0

.8

554.4

.8

395.1

.8

306.9

15.0

916.7

25.0

550.

35.0

392.8

45.0

305.6

.2

904.6

.2

545.6

.2

390.6

.2

304.2

.4

892.9

.4

541.3

.4

388.4

.4

302.9

.6

881.4

.6

537.1

.6

386.2

.6

301.5

.8

870.2

.8

532.9

.8

384.1

.8

300.2

16.0

859.4

26.0

528.8

36.0

381.9

46.0

298.9

.2

848.8

.2

524.8

.2

379.8

.2

297.6

.4

838.4

.4

520.8

.4

377.7

.4

296.3

.6

828.3

.6

516.9

.6

375.7

.6

295.0

.8

818.4

.8

513.

.8

373.6

.8

293.8

17.0

808.8

27.0

509.2

37.0

371.6

47.0

292.5

.2

799.4

.2

505.5

.2

369.6

.2

291.3

.4

790.2

.4

501.8

.4

367.6

.4

290.0

.6

781.2

.6

498.2

.6

365.7

.6

288.8

.8

772.5

.8

494.6

.8

363.7

.8

287.6

18.0

763.9

28.0

491.1

38.0

361.8

48.0

286.4

.2

755.5

.2

487.6

.2

359.9

.2

285.2

.4

747.3

.4

484.2

.4

358.1

.4

284.1

.6

739.2

.6

480.8

.6

356.2

.6

282.9

.8

731.4

.8

477.4

.8

354.4

.8

281.7

19.0

723.7

29.0

474.1

39.0

352.6

49.0

280.6

.2

716.1

.2

470.9

.2

350.8

.2

279.4

.4

708.8

.4

467.7

.4

349.0

.4

278.3

.6

701.5

.6

464.5

.6

347.2

.6

277.2

.8

694.4

.8

461.4

.8

345.5

.8

276.1

40

ENGINE TESTS.

Table of

(Continued).

M. E. P.

13750

M.E. P.

13750

M.E. P.

13750

M. E. P.

13750

M.E. P.

M.E. P.

M.E. P.

M.E. P.

50.0

275.0

60.0

229.2

70.0

196.4

80.0

171.9

.2

273.9

.2

228.4

.2

195.9

.2

171.4

A

272.8

.4

227.6

.4

195.3

.4

171.0

.6

271.7

.6

226.9

.6

194.7

.6

170.6

.8

270.6

.8

226.1

.8

194.2

.8

170.2

51.0

269.6

61.0

225.4

71.0

193.6

81.0

169.7

.2

268.5

.2

224.7

.2

193.1

.2

169.3

.4

267.5

.4

223.9

.4

192.5

.4

168.9

.6

266.4

.6

223.2

.6

192.0

.6

168.5

.8

265.4

.8

222.5

.8

191.5

.8

168.1

52.0

264.4

62.0

221.8

72.0

191.0

82.0

167.7

.2

263.4

.2

221.1

.2

190.4

.2

167.2

.4

262.4

.4

220.3

.4

189.9

.4

166.9

.6

261.4

.6

219.6

.6

189.4

.6

166.4

.8

260.4

.8

218.9

.8

188.9

.8

166.1

53.0

259.4

63.0

218.2

73.0

188.3

83.0

165.6

.2

258.4

.2

217.6

.2

187.8

.2

165.3

.4

257.5

.4

216.9

.4

187.3

.4

164.8

.6

256.5

.6

216.2

.6

186.8

.6

164.5

.8

255.5

.8

215.5

.8

186.3

.8

164.1

54.0

254.6

64.0

214.8

74.0

185.8

84.0

163.7

.2

253.6

.2

214.2

.2

185.3

.2

163.3

.4

252.7

.4

213.5

.4

184.8

.4

162.9

.6

2518

.6

212.8

.6

184.3

.6

162.5

.8

250.9

.8

212.2

.8

1838

.8

162.1

55.0

250.0

65.0

211.5

75.0

183.3

85.0

161.7

.2

249.1

.2

210.9

.2

182.8

.2

161.4

.4

248.2

.4

210.2

.4

182.3

.4

161.0

.6

247.3

.6

209.6

.6

181.9

.6

Io0.6

.8

246.4

.8

208.9

.8

181.4

.8

160.2

56.0

245.5

66.0

208.3

76.0

180.9

86.0

159.9

.2

244.6

.2

207.7

.2

180.4

.2

159.5

.4

243.8

.4

207.1

.4

180.0

.4

159.1

.6

242.9

.6

206.4

.6

179.5

.6

158.7

.8

242.1

.8

205.8

.8

179.0

.8

158.4

57.0

241.2

67.0

205.2

77.0

178.6

87.0

158.0

.2

240.4

.2

204.6

.2

178.1

.2

157.7

.4

239.5

.4

204.0

.4

177.6

.4

157.3

.6

238.7

.6

203.4

.6

177.2

.6

157.0

.8

237.8

.8

202.8

.8

176.7

.8

156.6

58.0

237.0

68.0

202.2

78.0

176.8

88.0

156.2

.2

236.2

.2

201.6

•2

175.8

.2

155.9

.4

235.4

.4

201.0

.4

175.4

.4

155.5

.6

234.6

.6

200.4

.6

174.9

.6

155.2

.8

233.8

.8

199.8

.8

174.5

.8

154.8

59.0

2330

69.0

199.3

79.0

174.1

89.0

154.5

.2

232.2

.2

198.7

.2

173.6

.2

154.1

.4

231.4

.4

198.1

.4

173.2

.4

153.8

.6

230.7

.6

197.6

.6

172.7

.6

153.5

.8

229.9

.8

197.0

.8

172.3

.8

153.1

HOW THE TESTS WERE CONDUCTED.

41

Table of

M. Mi.

(Concluded).

M. E.P.

13750
M.E. P.

M.E. P.

13750

M.E. P.

13750
M.E. P.

M.E. P.

13750

M. E.P.

M. E. P.

90.0

152.8

97.6

140.9

126

109.13

164

83.84

.2

152.4

.8

140.6

7

108.27

165

83.33

.4

152.1

98.0

140.3

8

107.42

6

82.83

.6

151.7

.2

140.

9

106.59

7

82.34

.8

151.4

.4

139.7

130

105.77

8

81.85

91.0

151.1

.6

139.4

1

104.96

9

81.36

.2

150.8

.8

139.1

2

104.17

170

80.88

.3

150.5

99.0

138.9

3

103.38

1

80.41

.6

150.1

2

138.6

4

102.61

2

79.94

.8

149.8

A

138.3

135

101.85

3

79.48

92.0

149.5

.6

138.

6

101.10

4

79.02

.2

149.2

.8

137.8

7

100.36

175

78.57

.4

148.8

100

137.5

8

99.64

6

7813

.6

148.5

1

136.14

9

98.92

7

77.68

.8

148.2

2

134.8

140

98.21

8

77.25

93.0

147.9

3

133.5

1

97.52

9

76.82

.2

147.5

4

132.21

2

96.83

180

76.39

.4

147.2

105

130.95

3

96.15

1

75.97

.6

146.9

6

129.71

4

95.49

2

75.55

.8

146.6

7

128.5

145

94.83

3

75.14

94.0

146.3

8

127.31

6

94.18

4

74.73

.2

146.

9

126.15

7

93.54

185

74.32

.4

145.6

110

125.

8

92.91

6

73.93

.6

145.3

1

123.88

9

92.28

7

73.53

.8

145.

2

122.77

150

91.67

8

73.14

95.0

144.7

3

121.68

1

91.06

9

72.75

.2

144.4

4

120.61

2

90.46

190

72.37

.3

144.1

115

119.57

3

89.87

!

71.99

.6

143.8

6

118.54

4

89.29

2

71.62

.8

143.5

7

117.52

155

88.71

3

71.25

96.0

143.2

8

116.53

6

88.14

4

70.88

.2

142.9

9

115.55

7

87.59

195

70.51

.4

142.6

120

114.58

8

87.03

6

70.15

.6

142.3

1

113.64

9

86.48

7

69.80

.8

142.

2

112.71

160

85.94

8

69.44

97.0

141.7

3

111.79

1

85.40

9

69.10

.2

141.4

4

110.89

2

84.88

200

68.75

.4

141.2

125

110.

3

84.36

PART II.

FEED-WATEK TESTS.

SIMPLE ENGINES.

[These engines are all horizontal, unjacketed, and of the automatic cut-off
type, with fly-ball governor, unless otherwise specified.]

4:"!

ENGINE No. 1.

Simple Non- Condensing.

Kind of engine Four-valve (Corliss)

Number of cylinders .»*.... '1

Diameter of cylinder . ... J ./ :. ' '. .... 23 in.

Diameter of piston-rod 3* in.

Stroke of piston ''.,' . ;:C"; 5 ft-

Clearance .......... 2* %

H. P. constant for 1 Ib. m. e. p. one revolution per min. .1247

Inside diameter of steam pipe 7 in.

Inside diameter of exhaust pipe . . »; 8 in.

Condition of valves and pistons regarding leakage . . „ Practically tight

Data and Results of Feed- Water Test, Engine No. 1.

Character of steam Ordinary

Duration . „ 5.75 hrs.

Weight of feed-water consumed 48,741 Ibs.

Feed-water consumed per hour 8,477 Ibs.

Pressure in steam pipe above atm 72.3 Ibs.

Mean effective pressure 33.08 Ibs.

Revolutions per minute . . . . . . . 74.7

Indicated horse-power .... .;... . V. .... 305.2 H. P.

Feed-water consumed per I. H. P. per hour . 27.77 Ibs.

Measurements based, on Sample Diagrams.

Initial pressure above atmosphere 72.8 Ibs.

Steam-pipe pressure above atmosphere 73.6 Ibs.

Cut-off pressure above zero „ .' ..•_ . 66.5 Ibs.

Release pressure above zero . 24.3 Ibs.

Mean effective pressure 33. 12 Ibs.

Back pressure at mid stroke above atmosphere ' 2.8 Ibs.

Proportion of stroke completed at cut-off .367

Steam accounted for at cut-off ..„..- 23.32 Ibs.

Steam accounted for at release 23.66 Ibs.

Proportion accounted for at cut-off .84

Proportion accounted for at release .852

Engine No. 1 is supplied with steam in part from a number of
vertical boilers, and in part from a single boiler of the horizontal
return tubular type. The mixed steam showed no superheat-
ing, though probably commercially dry. The valves and pistons
were all fairly tight. The load consisted of cotton machinery.

On another occasion two tests were made on this engine, the
first with ordinary steam as above, and the second with super-
heated steam, the horizontal boiler in the latter case being out
of service. The principal data and results were as follows :

45

ENGINE TESTS.

TEST.
CHARACTER OF STEAM.

No. \b.
ORDINARY.

NO. Ic.
SUPERHEATED

82°.

Mean effective pr6ssur6 Ibs

34 46

35 07

Proportion of stroke completed at cut-off

.375

.392

Feed-water consumed per I. H P. per

hour ........ . Ibs.

29.34

26.83

Steam accounted for at cut-off . . Ibs.

24.6

25.42

Steam accounted for at release . . Ibs.

25.26 '

24.15

Proportion accounted for at cut-off ~ .

.839

.947

Proportion accounted for at release . ...

.861

.900

The marked effect of superheating is indicated by comparing
these two tests. By superheating the steam 82 degrees the con-
sumption of feed-water per I. H. P. per hour was reduced about
9 per cent. A feature in these results is the effect upon the
steam accounted for by the indicator. It increases between cut-
off and release from 24.6 pounds to 25.26 pounds when ordi-
nary steam is used, whereas the contrary effect is produced
under the influence of the superheating, the quantity falling
from 25.42 pounds to 24.15 pounds.

ENGINE No. 1

Head End

Crank End

-60

-40

-20

- O

-60

-40

-20

ENGINE No. 2.

Simple Non- Condensing.

Kind of engine Four-valve (Corliss)

Number of cylinders 1

Diameter of cylinder 28.5 in.

Diameter of piston-rod 4 in.

Stroke of piston 59.5 in.

Clearance 3 %

H. P. constant for 1 Ib. m. e. p. one revolution per min. .1898

Inside diameter of steam pipe 8 in.

Condition of valves and piston regarding leakage . . . Fairly tight.

Data and Eesults of Feed-Water Test, Engine No. 2.

Character of steam . ., ' . Ordinary

Duration .'• . . 6.08 hr.

Weight of feed-water consumed . . . ..;.'... . . . 79,467 Ibs.

Feed-water consumed per hour 13,070 Ibs.

Pressure in steam pipe above atmosphere J._. 101 Ibs.

Mean effective pressure 41.18 Ibs.

Revolutions per minute 64.-8

Indicated horse-power 506.5 H. P.

Feed-water consumed per I. H. P. per hour . . . . . . 25.8 Ibs.

Measurements based on Sample Diagrams.

Initial pressure above atmosphere '. 91 'bs.

Cut-off pressure above zero , . 82.9 Ibs.

Release pressure above zero ...... 26.3 Ibs.

Mean effective pressure ..'..,. . . . 41.18 Ibs.

Back pressure at mid -stroke above atmosphere 4.2 Ibs.

Proportion of stroke completed at cut-off .315

Steam accounted for at cut-off 21.06 Ibs.

Steam accounted for at release 21.35 Ibs.

Proportion accounted for at cut-off .817

Proportion accounted for at release. .828

Engine No. 2 is supplied with steam from water tube boilers.
A calorimeter test showed less than one per cent of moisture.
The steam valves and piston were tight. The exhaust valves
leaked a small amount. The load was that of a cotton-mill.

47

ENGINE No. 2

Head End

-100
-80
-60
-40
-20
- 0

Crank End

ENGINE No. 3.

Simple Condensing.
Kind of engine . . . .' . . . . . . . . . . . Four-valve (Corliss)

Number of cylinders ............. 2

Diameter of each cylinder

Diameter of piston-rod

Stroke of each piston

Clearance , i

H. P. constant for 1 Ib. m. e. p. one revolution per rnin.

Inside diameter of steam pipe

Inside diameter of exhaust pipe . .' »

Condition of valves and pistons regarding leakage . . .

Data and Results of Feed- Water Tests, Engine No. 3.

in.
in.

ft.

20i
4

3 Of

fO

.1532
8 in.

8 in.

Fairly tight.

CONDITIONS AS TO USE OF CONDENSER.

TEST A.

ALL-
CONDENSING.

TEST B.

THREE ENDS CON-
DENSING, ONE END
NON-CONDENSING.

Character of steam
Duration ........
Weight of feed-water consumed .
Feed-water consumed per hour .
Pressure in steam pipe above
atmosphere

hrs.
Ibs.
Ibs.

Ibs.
in.
Ibs.

H.P.

Ibs.

Ordinary
4.75
21,185.
4,460.

67.2
26.2
22.79
60.3
210.5

21.11

Ordinary
4.75
24,671.
5,194.

69.1
26.5
24.79
60.3
229.

22.68

Vacuum in condenser ....
Mean effective pressure . . .
Revolutions per minute - ...
Indicated horse-power ....
Feed- water consumed per I. H. P.
per hour

Measurements based on Sample Diagrams.

Initial pressure above atmosphere Ibs.

60.8

64.1

AVERAGE OF
THREE
CONDENSING
ENDS.

NON-
CON-
DENSING
END.

Cut-off pressure above zero . . Ibs.
Release pressure above zero . . Ibs.
Mean effective pressure . . . Ibs.
Back pressure at mid-stroke above
or below atmosphere . . . Ibs.
Proportion of stroke completed
at cut-off Ibs

59.9
9.3
23.23

11.9
138

63.
10.5
26.41

- 12.
.152

63.
13.5
19.01

+ 1.
.185

Steam accounted for at cut-off . Ibs.
Steam accounted for at release . Ibs.
Proportion accounted for at cut-
off (average for the whole
engine)
Proportion accounted for at re-
lease

13.85
14.77

.654
697

13.95
14.59

.6

.7

21.19
24.06

95
48

50 ENGINE TESTS.

Engine No. 3 has a pair of cylinders exhausting into a jet
condenser operated by a direct-connected air-pump. The ex-
haust passages and piping are arranged so as to run one end of
one cylinder non-condensing. One test was made running both
cylinders condensing, and one test running three ends condens-
ing and one end non-condensing. The engine is supplied with
steam from horizontal return tubular boilers. The quality of
the steam was not tested, but it was probably commercially dry.
One steam valve and the exhaust valves of one cylinder showed
some leakage. The remaining valves, and the pistons, were
fairly tight. The engine was employed in driving several man-
ufactories working in connection with water-wheels.

The loss in steam due to running one end of the cylinder
non-condensing is about 1%. The gain in fuel that would
be produced by utilizing the exhaust steam from this end for
heating feed-water for the boilers, assuming that it increases
the temperature from 60 to 210 degrees, is sufficient to cover
the increased steam consumption and leave a net fuel saving of
some 7.

ENGINE No. 3 a

R,H. Cyl. Crank End

—60

— 40
—20

— 0

— 10

— 60

— 40

— 20

— 0

— 10

60-
40 —
20 —

0—
10-

60-
40-
20—

0-
10-

L.H. Cyl. Head End

L,H. Cyl. Crank End

ENGINE No. 3b

R.H. Cyl. Head End

R.H. Cyl. Crank End

-60

-40
-20

- 0

10

-60

-40
-20

— 0

— 10

60-

40-

20-

O-1

L,H.CyI. Head End

60-

40-

20-

0-
10-

L.H. Cyl. Crank End

ENGINE No. 4.

Simple Condensing.

Kind of engine , , ,

Number of cylinders ,

Diameter of cylinder

Diameter of piston-rod .... . . . , V.

Stroke of piston . . , ... .

Clearance

H.P. Constant for one Ib. m.e.p., one rev. per minute
Inside diameter of steam pipe .... . , '.'•-.-»
Inside diameter of exhaust pipe . . . . » . . ..
Condition of valves and piston regarding leakage .

Four-valve (Corliss)
1

34.2 ins.
4i ins.

5 ft.
3 %

.2764

6 ins.

7 ins.
Fairly tight.

Data and Results of Feed Water Test, Engine No. 4.
Character of steam Superheated 25

Duration

Weight of feed-water consumed ....
Feed-water consumed per hour ....
Pressure in steam pipe above atmosphere .

Vacuum in condenser

Mean effective pressure

Rev. per min

Indicated horse-power

Feed-water consumed per I. H. P. per hour

deg.
hra.

Ibs.

Ibs.

Ibs.

10.8
125,420
11,613

83

24.8

35.53

53.3
523.43 H. P.

22.19 Ibs.

ins.
Ibs.

Measurements Based on Sample Diagrams : —

Initial pressure above atmosphere .
Steam-pipe pressure above atmosphere

76.1 Ibs.
83 Ibs.

HEAD END.

NON-CONDENSING .

CRANK END.
CONDENSING.

Cut-off pressure above zero

Ibs.

71.9

76.7

Release pressure above zero

Ibs.

17.5

18.1

Mean effective pressure

Ibs.

28.22

41.88

Back pressure at mid-stroke, above or

below atmosphere

Ibs.

+ 2.1

— 11.7

Proportion of stroke completed at cut-off

Ibs.

.237

.230

Steam accounted for at cut-off .

Ibs.

18.79

15.18

Steam accounted for at release .

Ibs.

18.75

15.43

Proportion accounted for at cut-off

(average of two ends)

Ibs.

.766

Proportion accounted for at release

Ibs.

.77

OF THE

54

ENGINK TESTS.

Engine No. 4 exhausts into a jet condenser with direct-con-
nected air-pump. One end is run condensing, and the other
end non-condensing. The boilers are of the vertical type,
which superheat the steam. Steam was supplied for other
purposes than power, and the amount thus used was deter-
mined and allowed for. There was slight leakage of the steam
valves. The exhaust valves and piston were practically tight.
The load was that of a cotton mill.

ENGINE No.4

80-

60-

40—

20-

Head End

60-

40—

20-

O-
10-

Crank End

ENGINE No. 5.

Simple Condensing.

Kind of engine . ....'. Four-valve (Corliss)

Number of cylinders . 2

Diameter of each cylinder 32.5 ins.

Diameter of each piston-rod . \ ....... 4? ins.

Stroke of each piston ..."...,". 4.5 ft.

Clearance 3 %

H.P. Constant for one Ib. M.E.P. one rev. per min. . . .4484

Inside diameter of steam-pipe 7 ins_

Condition of valves and pistons regarding leakage . . . Some leakage.

Data and Results of Feed- Water Test, Engine No. 5.

Character of steam , . . Ordinary

Duration 5.55 nrs.

Weight of feed-water consumed . . . . . .... . 100,253 Ibs.

Feed-water consumed per hour . . . . . ..... 18,063 Ibs.

Pressure in steam pipe 71.1 ibs.

Vacuum in condenser . 26.2 in.

Mean effective pressure 32.41 Ibs.

Re volutions per minute 47.3

Indicated horse-power . 687.39 H. P.

Feed-water consumed per I. H. P. per hour . . „ . . . 26.28 Ibs.

Measurements Based on Sample Diagrams.

CONDENSING
CYLINDER.

NON-
CONDENSING
CYLINDER.

Initial pressure above atmosphere . . . Ibs.

Cut-off pressure above zero Ibs.

Release pressure above zero Ibs.

Mean effective pressure . • Ibs.

Back pressure at mid-stroke, above or be-
low atmosphere Ibs.

Proportion of stroke completed at cut-off .

Steam accounted for at cut-off .... Ibs.

Steam accounted for at release .... Ibs.

Proportion accounted for at cut-oft (aver-
age for whole engine)

Proportion accounted for at release .

70.3
63.5
20.1
39.54

-9.4

.298
16.78
17.36

.784
.813

65.2
63.
20.
26.2

+ 4.9

.308
24.47
25.39

Engine No. 5 has a pair of cylinders, one of which exhausts
into a jet condenser, with direct-connected air-pump, and the
other is non-condensing. Steam is furnished from cylinder

55

56 ENGINE TESTS.

boilers, and it appeared to be commercially dry. A small
amount was used for other purposes than running the engine,
but the quantity thus consumed was determined, and allow-
ance made for it. The valves and piston of one cylinder
showed some leakage ; those of the other cylinder were fairly
tight. The load consisted of cotton machinery.

ENGINE No. 5

R.H.Cyl. Head End

60-

40-

20-

0-1

L.H.Cyl. Head End

L.H.Cyl. Crank End

-60

_40

-20

•— 0

ENGINE No. 6,

Simple Condensing.

Kind of engine Four-valve (Corliss)

Number of cylinders 2

Diameter of each cylinder ... 26j in.

Diameter of each piston rod 3f iu.

Stroke of each piston . 5 ft.

Clearance • .. .-" 3 ^

H. P. Constant for one Ib. m. e. p. one rev. per minute, .3254

Inside diameter of steam pipe 8 in.

Inside diameter of exhaust pipe . . , . ..... 10 in.

Condition of valves and pistons regarding leakage . . . Some leakage.

Data and Results of Feed-Water Test, Engine No. 6.

Character of steam i. . , . Ordinary

Duration . . . . . . , . . . • , . . . . . . . 5.08 hrs.

Weight of feed-water consumed 71,150 Ibs.

Feed-water consumed per hour . . 14,006 Ibs.

Pressure in steam pipe . : . . ». . '. . . . '. . . 84.4 Ibs.

Vacuum in condenser . . , ... . . . . . '. . 27.3 in.

Mean effective pressure . . . . . . , . . ... . 36.73 Ibs.

Eevolutions per minute . . . _,- . . . . ..... . 51.1

Indicated horse-power . . . ... . .... . v . 610.74 H. P.

Feed-water consumed per I. H. P. per hour . . . ' . . . 22.95 Ibs.

Measurements based on Sample Diagrams.

THREE

ENDS

CONDENSING.

NON-
CONDENSING
END.

Initial pressure above atmosphere . . . Ibs.

Cut-off pressure above zero Ibs.

Kelease pressure above zero Ibs.

Mean effective pressure Ibs.

Back pressure at mid stroke, above or be-
low atmosphere Ibs.

Proportion of stroke completed at cut-off .

Steam accounted for at cut-off .... Ibs.

Steam accounted for at release .... Ibs.

Proportion accounted for at cut-off (aver-
age for whole engine

Proportion accounted for at release (aver-

77.3
74.6
17.2
39.46

10.2

.233
15.81
15.56

.757

.754

76.
73.8
20.4
30.03

4.5

.271
22.12
22.63

Engine No. 6 has a pair of cylinders exhausting into a jet
condenser with direct-connected air-pump. One cylinder was

58

ENGINE No, 6. 59

run condensing, and one end of the other cylinder non-con-
densing. Steam is supplied from sectional boilers with large
drum, and from all appearances it was in a commercially dry
condition. Both pistons showed some leakage, but the valves
were all fairly tight. The load consisted of cotton machinery.

ENGINE No. 6

R.H. Cyl, Head End

—60

40-

20-

10— '

ENGINE No. 7.

Simple Non-Condensing.

Kind of engine . ^ . . . . Four-valve (Corliss)

Number of cylinders 1

Diameter of cylinder 26i3s iu.

Diameter of piston rod 31 in.

Stroke of piston . . .... . . • • ..:.... 4 ft.

Clearance . . .' 3 %

H. P. constant for one Ib. in. e. p. one revolution per min. .1285

Inside diameter of steam pipe 6 in.

Condition of valves and piston regarding leakage . . . Some leakage.

Data and Results of Feed-Water Test, Engine No. 7.

Character of steam '. Ordinary

Duration 5.1 hrs.

Weight of feed-water consumed 34,386 . Ibs.

Feed-water consumed per hour 6,742 Ibs.

Pressure in steam pipe above atmosphere . . . .-.',. . 80.5 Ibs.

Mean effective pressure . . . . . . . .... . . 27.82 Ibs.

Revolutions per minute C. • ^4.7

Indicated horse-power . . 232.3 H. P.

Feed- water consumed per I. H. P. per hour 29.03 Ibs.

Measurements based- an- Sample Diagrams.

Initial pressure above atmosphere ., 79.6 Ibs.

Cut-off pressure above zero 76.6 Ibs.

Release pressure above zero 19.6 Ibs.

Mean effective pressure ;....,,. 27.3 Ibs.

Back pressure at mid stroke above atmosphere 5.4 Ibs.

Proportion of stroke completed at cut-off . . . . . . . . .237

Steam accounted for at cut-off . ... . '. .... ... 21.77 Ibs.

Steam accounted for at release . . . , . . . . . . . 23.31 Ibs.

Proportion, accounted for at cut-off . . . . .7' . T~ 7_ . .75

Proportion accounted for at release .803

Engine No. 7 is supplied with steam from horizontal return
tubular boilers, presumably in a commercially dry condition.
The valves were fairly tight, but there was considerable leakage
of the piston. The load consisted of cotton machinery.

(51

80-,

ENGINE No. 7

60-

Head End

40-

20-

80-i

60-

Crank End

40-

20-

o-1

ENGINE No. S.

Simple Condensing.

Kind of engine

Number of cylinders

Diameter of cylinder

Diameter of piston rod

Stroke of piston

Clearance

H.P. constant for one Ib. m.e.p. one rev. per min.
Condition of valves and piston regarding leakage .

Data and Results of Feed-Water Tests.

Four-valve (Corliss)

1

ins.

ins.

ft.

30

41
6
3 %

.2543
Fairly tight.

CONDITIONS AS TO PRESSURE.

TEST A.
ORDINARY.

TEST B.
EXTRA.

Character of steam

Superhtd. 37°

Superhtd. 37°

Duration

hrs.

5.667

5.167

Weight of feed-water consumed ....

Ibs.

40,281.

34,984.

Feed-water consumed per hour ....

Ibs.

7,104.

6,771.

Pressure in steam-pipe above atmosphere .

Ibs.

53.1

68.2

Vacuum in condenser

ins.

29.7

29.8

Mean effective pressure

Ibs.

26.63

26.3

Revolutions per minute

54.1

54.1

Indicated horse-power

H.P.

366.4

361.8

Feed-water consumed perl.H.P. per hour

Ibs. 19.39

18.71

Measurements based on Sample Diagrams.

CONDITIONS AS TO PRESSURE.

TEST A.
ORDINARY.

TEST B.
EXTRA.

Initial pressure above atmosphere . . .
Cut-off pressure above zero

Ibs.
Ibs

46.5
47 0

61.5
58 6

Release pressure above zero
Mean effective pressure

Ibs.
Ibs

11.1
26 84

9.8
26 39

Back pressure at mid-stroke below atm.
Proportion of stroke completed at cut-off .
Steam accounted for at cut-off ....
Steam accounted for at release ....
Proportion accounted for at cut-off .
Proportion accounted for at release

Ibs.
Ibs.
Ibs.
Ibs.

— 12.4
.247
15.89
15.19
.819
.783

— 12.4
.165
13.98
13.72

.747
.733

Engine No. 8 exhausts into a jet condenser with direct-con-
nected air-pump. Steam is supplied through a 12-inch pipe,
160 feet in length, from vertical boilers which superheat. The
amount of superheating at the boilers on the test was 67 degrees.

63

64 ENGINE TESTS.

It was subsequently found that the loss of temperature between
the boilers and the throttle valve was 60 degrees ; so that the
steam entering the cylinder was still in a slightly superheated
condition. The valves and pistons were fairly tight. The load
consisted of cotton machinery.

Advantage was taken of the comparatively light load to make
a trial of the engine under two pressures. The other conditions
of running were the same in both cases.

It appears that the increase of pressure from 53 pounds to
68 pounds was attended by a reduction in the steam consump-
tion amounting to nearly four per cent. There is a marked
increase in the cylinder condensation (and leakage), with the
shortening of the cut-off and increase of pressure.

ENGINE No. 8 a

40-

20-

40-

20-

Head End

60—,

ENGINE No. 8b

40-

Head End

20-

0—
10—

60-
40-
20-

0—
10-

CrankEnd

ENGINE No. 9,

Simple Condensing.

Kind of engine ......

Number of cylinders

Diameter of each cylinder

Diameter of each piston rod

Stroke of each piston

Clearance „

H.P. constant for one Ib. m.e.p. one rev. per minute .

Inside diameter of steam pipe

Condition of valves and pistons regarding leakage .

Four valve (Corliss)

2

30i ins.
41 ft.
6 ft.

3 %

.515

8 ins.
Some leakage.

Data and Results of Feed- Water Tests.

TEST A.

TEST B.

THREF

CONDITIONS AS TO USE OF CONDENSER.

ALL
CON-

FOURTHS
Cox

DENSING

DENSING.

Character of steam . . .-^. . . . .

Supd. 24°

Super htd. 24°

Duration . -,

hrs

5 1

5 37

Weight of feed-water consumed . .''.'.

Ibs.

70,565.

83,060.

Feed-water consumed per hour . ...

Ibs.

13,838.

15,4(57.

Pressure in steam pipe above atmosphere .

Ibs.

70.8

73.4

Vacuum in condenser * .

ms.

26.7

26.7

Mean effective pressure »

Ibs

32 00

31 44

Revolutions per minute -

46

46

Indicated horse-power . ...

H P

758 27

758 10

Feed-water consumed per I. H.P. per hour

Ibs.

18.25

20.4

Measurements based on Sample Diagrams.

CONDITIONS AS TO USE OF CONDENSER.

NON-
CONDENS-
ING
•END.

THREE
ENDS
CONDENS-
ING.

Initial pressure above atmosphere . . . Ibs.
Cut-off pressure above zero Ibs.
Release pressure above zero Ibs.
Mean effective pressure . ._..;. . . . . Ibs.
Back pressure at mid-stroke, above or below
atmosphere Ibs.

67.7
70.4
12.9
32.10

— 11 5

70.7
69.6
17.2
26.11

+ 4 0

67.8
72.5
13.9
34.54

11 5

Proportion of stroke completed at cut-off .
Steam accounted for at cut-off .... Ibs.
Steam accounted for at release .... Ibs.
Proportion accounted for at cut-off .
Proportion accounted for at release . . .

.185
14.97
14.52
.82
.796

.247

21.94
21.88

.8,
.8

.202
14.45
14.47
56

67

Engine No. 9 has a pair of cylinders exhausting into a jet
condenser with direct-connected air-pump. Steam is supplied
in a slightly superheated condition from vertical boilers.
Arrangements are made so that one end of one cylinder can be
run non-condensing. One test was made with this end operat-
ing non-condensing, and another when the whole engine was
running condensing. The exhaust valves and steam valves of
one cylinder were fairly tight. The steam valves of the other
cylinder and the pistons of both cylinders showed some leakage.
The load consisted of cotton machinery.

The loss of steam due to running one end of one cylinder
non-condensing is 2.15 pounds per I. H. P. per hour, or 11.8%
of the quantity required when running condensing.

ENGINE No. 9 a

60-

R.H.Cyl. Head End

ENGINE No.Qb

60-

40-

20-

o-1

60-

j
40 H

20-

o-

10-

RH. Cyl. Head End

R.H.Cyl. Crank End

L.H. Cyl. Head End

-60

-40

ENGINE No. 10.

Double Valve

o

Simple Condensing Engine.

Kind of engine ... ...... /. . . .

Number of cylinders . .' ." • .' .... /

Diameter of each cylinder . . . . " „ ..-'.'. . . . . . 17 in.

Diameter of each piston rod . . ... ......... 2.75 in.

Stroke of each piston . .'._.'._ 24.2 in.

Clearance . . . %. -- . . . . ~ 2 %

H. P. Constant for one Ib. in. e. p. one rev. per minute . . . .0551 H.P.

Inside diameter of steam pipe. — ^ .- .-..-.,- ..- ..,..- ,. , .--.-. 6 in.

Condition of valves and pistons regarding leakage . . . . . Some. leakage

Data and Results of Feed- Water Tests, Engine No. 10.

CONDITIONS AS TO USE OF CONDENSER.

CONDENSING.

XON-
CONDENSING.

Character of steam . . . . . .^ „-•'.'

Superhtd. 16°

Superhtd. 41°

Duration . . . " . .

hrs.

5.7

5.21

Weight of feed-water consumed ....

Ibs.

39,299.

41,415.

Feed-water consumed per hour ....

Ibs.

6,895.

7,952.

Pressure in steam pipe above atmosphere .

Ibs.

79.

75.9

Vacuum in condenser

ins.

23.6

Mean effective pressure

Ibs.

39.36

36.82

Revolutions per minute . . ' . , . . .

154.7

152.9

Indicated horse-power I

H.P.

336.2

310.1

Feed-water consumed per I. H.P. per hour

Ibs.

20.51

25.64

i

Measurements based on Sample Diagrams.

CONDITIONS AS TO USE OF CONDENSER.

CONDENSING.

NON-
CONDENSING.

Initial pressure above atmosphere . . .

Ibs.

74.5

76.4

Steam-pipe pressure above atmosphere .

Ibs.

78

79

Cut-off pressure above zero . . . ~~. T- r

Ibs.

72.9

72.8

Release pressure above zero . ..... .

Ibs.

19.7

25.2

Mean effective pressure

Ibs.

42.15

37.43

Back pres. at mid stroke above or below atm.

Ibs.

— 10.1

+ 1.0

Proportion of stroke completed at cut-off .

.262

.337

Steam accounted for at cut-off . . -.,.' .7

Ibs.

15.82

20.78

Steam accounted for at release . ...

Ibs.

15.53

20.42

Proportion accounted for at cut-off .

.771

.811

Proportion accounted for at release . . .

.757

.795

Engine No. 10 has a pair of cylinders, with condenser of
the siphon type, which is supplied with water by means of a
belt pump operated by the engine. Ths main valves are bal-

70

ENGINE No. 10. 71

anced slides. The cut-off valve rides on a seat in the interior
of the main value, which is of box pattern. The cut-off valve
is controlled by a shaft governor. One test was made with
the engine running condensing, and one running non-condens-
ing. Steam is furnished by superheating vertical boilers, which
are 190 feet distant from the throttle valves, the connecting
pipe being 10 inches in diameter. The loss of temperature
from the boilers to the engine amounted to 54 degrees. The
pistons and cut-off valves were practically tight. The main
valves showed some leakage. The engine worked in connec-
tion with water-wheels, and supplied power to a cotton-mill.

From these results it appears that the consumption of steam
when the engine was run condensing was 5.13 Ibs. per I. H. P.
per hour less than when run non-condensing, or 20%.

In making this comparison it should be observed that there
was a comparatively poor vacuum, both in the cylinders and in
the condenser, which acted unfavorably upon the condensing
result ; and this was further influenced in the same direction
by the relatively small amount of superheating.

ENGINE No.lOa

60-
40-
20-

0-
10-

60-
40—
20-

V

R.H.Cyl. Head End

J

R.H.Cyl. Crank End

60-

40—

20—

60—

40—

ENGINE No. lOb

80—1

60 —

40 —

20—

0
80^

60-
40—
20-

0-
80 -,

60-
40-
20-

0-1
80^

60 —

40-

20-^

0 —

RH, Cyl. Head End

R.H.Cyl. Crank End

L.H.Cyl. Head End

L.H. Cyl. Crank End

OPTHK '*?

UNIVERSITY

ENGINE No. 1 1.

Simple Non-Condensing Engine.

Kind of engine . . . . . . . . ... . - Four valve

Number of cylinders ..... ..... . . 1

Diameter of cylinder '..-...',. . . . . ... . .161 ins.

Diameter of piston rod -. . . . . 21 ins.

Stroke of piston 32 ins.

Clearance .... . . . . . _~ . . 4 %

H.P. constant for one Ib. in. e. p. one rev. per ruin 0346H.P.

Inside diameter of steam pipe 5 in.

Condition of valves and piston regarding leakage . . . Considerable leakage

Data and Results of Feed-Water Test.

Character of steam Ordinary

Duration 5.47 hrs.

Weight of feed-water consumed . . . . . '. . .' . . 10,277 Ibs.

Feed-water consumed per hour 1,879 Ibs.

Pressure in steam-pipe above atmosphere 61 Ibs.

Mean effective pressure 18.19 Ibs.

Revolutions per minute . . . ..... . . . . . . 79.8

Indicated horse-power 50.2 I. H.P.

Feed-water consumed per I. H. P. per hour ....... 37.43 Ibs.

Measurements based on Sample Diagrams.

Initial pressure above atmosphere 58.6 Ibs.

Cut-off pre .sure above zero . . . . , . 56.1 Ibs.

Release pressure above zero 16.7 Ibs.

Mean effective pressure . ............. 18.29 Ibs.

Back pressure at mid stroke above atmosphere '. 1.1 Ibs.

Proportion of stroke completed at cut-off .234

Steam accounted for at cut-off . . . . '. . .'..'•_,... .-, 21.52 Ibs.

Steam accounted for at release . . 27.42 Ibs.

Proportion accounted for at cut-off .... .575

Proportion accounted for at release . v . . ....... •«.-.••*-.--. . ,. /' .732

Engine No. 11 is controlled by a shaft governor. It lias
piston valves provided with means for adjustment to take up
wear. Steam is supplied from return tubular boilers, probably
in a commercially dry condition. The piston and one steam
valve were fairly tight. The other steam valve and both ex-
haust valves leaked. The engine was employed in driving a
machine-shop.

The effect of leakage, low pressure, and light load is seen in
the excessive consumption of steam shown on this test.

74

ENGINE No. 11

Head End

-60

40

20

- O

ENGINE No. 12,

Simple Condensing Engine.

Kind of engine Four valve (Corliss)

Number of cylinders 1

Diameter of cylinder 24i in.

Diameter of piston rod 3j in.

Stroke of piston *...... 4 ft.

Clearance .~ ..... 3 %

H. P. constant for one Ib. m. e. p. one revolution per mm. .112 H.P.

Inside diameter of steam pipe ...;...... 6 in.

Inside diameter of exhaust pipe . . . . . . . . 7 in.

Condition of valves and piston regarding leakage . . . Considerable leakage

Data and Results of Feed- Water Test.

Character of s'eam . . . . ... . . . . . . . Ordinary

Duration 5.07 hrs.

Weight of feed-water consumed . . . . . ... ; . 30,920 Ibs.

Feed-water consumed per hour ... . . . .... 6,099 Ibs.

Pressure in steam pipe above atmosphere . . ... *. . ' . 70.2 Ibs.

Vacuum in condenser ...... ' ". 21 in.

Mean effective pressure . . . ...-.-.,. . '. . '. . . . 33.06 Ibs.

Revolutions per minute 70.2

Indicated horse-power . 258.2 I. H.P.

Feed-water consumed per I. H. P. per hour ....... 23.62 Ibs.

Measurements based on Sample Diagrams.

Initial pressure above atmosphere , . . . 63.6 Ibs.

Cut-off pressure above zero . », . . .;;. . . . . . . . 56.1 Ibs.

Release pressure above zero .'.... ", . '•„ : . 17.8 Ibs-

Mean effective pressure . . ' . .... . > . . . . «... . . 33.31 Ibs.

Back pressure at mid stroke, below atmosphere ... . . . . 8.5 Ibs.

Proportion of stroke completed at cut-off 29

Steam accounted for at cut-off 16.99 Ibs.

Steam accounted for at release 17.75 Ibs.

Proportion accounted for at cut-off . .719

Proportion accounted for at release 751

Engine No. 12 exhausts into a jet condenser having a
direct connected air-pump. The joints about the air-pump were
out of repair, and the condenser was rendered somewhat ineffi-
cient. Steam is supplied from vertical boilers, which do not
superheat, but which appeared to furnish steam in a commer-

76

ENGINE No. 12.

77

cially dry condition. One of the steam valves leaked, but the
remaining valves were practically tight. The piston leaked
badly. The load consisted of cotton machinery.

Leakage and the poor vacuum are evidently accountable for
the comparatively low result obtained here.

ENGINE No. 12

Head End

Crank End

~7

-60
-40
-20

0

- 10

-60
-40
-20

- 0
-10

ENGINE No. 13.

Simple Non-Condensing Engine.

Kind of engine Single valve

Number of cylinders 1

Diameter of cylinder 14.5 in.

Diameter of piston rod 21 in.

Stroke of piston 13 in.

Clearance ........... ^ 10 %

H. P. constant for one Ib. in. e. p. one revolution per min. . . .0108 H.P.

Inside diameter of steam pipe . . . . . . 4 in.

Inside diameter of exhaust pipe 6 in.

Condition of valves and piston regarding leakage . . Considerable leakage

Data and Results of Feed-Water Test.

Character of steam Ordinary

Duration .... . . .^ . - ., . . ..--., 2.5 hr.

Weight of feed-water consumed . . . . .-.'-:. . . . - . 4,350 Ibs.

Feed-water consumed per hour . . . . . ... . . . 1,740 Ibs.

Pressure in steain pipe above atmosphere 102.5 Ibs.

Mean effective pressure . ..'•'.. . ">/'', ... ..... 20.07 Ibs.

Revolutions per minute . . . . . .'-.- . . . . . . 246

Indicated horse-power . . . . . . . . ..-,.,. . 53.26 I.H.P.

Feed-water consumed per I. H. P. per hour . . . . . . 32.67 Ibs.

Measurements based on Sample Diagrams.

Initial pressure above atmosphere ........... 98.1 Ibs.

Cut-off pressure above zero . ... . ....... . 97.0 Ibs.

Release pressure above zero . . . : . . . . . .- . . 40.8 Ibs.

Mean effective pressure . ,. 20.07 Ibs.

Back pressure at mid stroke above atmosphere . . . . . . -j-2.6 Ibs.

Proportion of stroke completed at cut-off .119

Steam accounted for at cut-off . . .. . ;";--.. . . . . . ; ,: 17.72 Ibs.

Steam accounted for at release .... . ." ". >-.. -. .. 22.59 Ibs.

Proportion accounted for at cut-off . . . . ..,?.,v ;. _. _ . . .539

Proportion accounted for at release _;__i...- • -591

Engine No. 13 is of the high-speed class, with a shaft
governor. The valve is of the piston type, unpacked. Steam
is supplied from a water-tube boiler, and is presumed to
be in a commercially dry condition. The piston was fairly
tight. The valve at one end was fairly tight, but at the other
end it leaked badly. The load consisted of a dynamo furnish-
ing current for electric lighting.

The leaking of the piston valve is evidently responsible in
some degree for the comparatively poor showing on this engine.

78

ENGINE No. 13

Head End

Crank End

-100

- 80
-60
-40
-20

- 0
r-100

- 80
-60
— 40
-20

- 0

ENGINE No. 14.

Simple Non- Condensing Engine.

Kind of engine ... . Single valve

Number of cylinders . .1

Diameter of cylinder 8.5 in.

Diameter of piston rod . . . If in.

Stroke of piston ........ ....... 10 in.

Clearance ......... v 8 %

H. P. constant for 1 Ib. m. e. p. one revolution per min. . . .0028 H.P.
Inside diameter of steam pipe ........... 2£ in.

Inside diameter of exhaust pipe 85 in.

Condition of valves and piston regarding leakage . . Considerable leakage

Data and Results of Feed- Water Test.

Character of steam Ordinary

Duration . 2£ hrs.

Weight of feed-water consumed . . . . . .' . . ;"\ . 2,357 Ibs.

Feed- water consumed per hour . . . .' 942.8 Ibs.

Pressure in steam pipe above atmosphere '. .,".:.;. . . 105.8 Ibs.

Mean effective pressure . . ... ... . - . . . 30.58 Ibs.

Eevolutions per minute . ,. .- .... . . . . . . 315

Indicated horse-power . . . ... . . . . . . . 27.35 I. H.P.

Feed-water consumed per I. H. P. per hour . » ^ •. . . . 34.44 Ibs.

Measurements based on Sample Diagrams.

Initial pressure above atmosphere , 99.6 Ibs.

Cut-off pressure above zero . . . . . .... f. " . . . 92.5 Ibs.

Release pressure above zero . . ..... . . . . . . . 34.1 Ibs.

Mean effective pressure 30.58 Ibs.

Back pressure at mid stroke above atmosphere . . . . . . . 1.7 Ibs.

Proportion of stroke completed at cut-off . . . . . . ... .194

Steam accounted for at cut-off • . . . . . . . ... ... 17.92 Ibs.

Steam accounted for at release . / . 21.17 Ibs.

Proportion accounted for at cut-off . ..'.-. . ... . . .52

Proportion accounted for at release . i . . .".-...,. .615

Engine No. 14 is of the high-speed class, controlled by a
shaft governor. It is provided with a piston valve which is
unpacked. Steam is supplied from a water-tube boiler, proba-
bly in a commercially dry condition. The piston was fairly
tight. The valve leaked badly. The load consisted of a dy-
namo furnishing current for electric lighting.

The boiler plant in this case is the same as that of Engine
No. 13.

The inferior economy exhibited here can be attributed in the
main to leakage.

80

ENGINE No. 14

Head End

ENGINE No. 15.

Simple Condensing Engine.

Kind of engine Four valve (Corliss)

Number of cylinders 2

Diameter of each cylinder 23 in.

Diameter of each piston rod 31 in.

Stroke of each piston 5 ft.

Clearance 3 %

H. P. constant for 1 Ib. m. e. p. one revolution per min. .249 H.P.

Inside diameter of steam pipe 6 in.

Inside diameter of exhaust pipe ......... 10 in.

Condition of valves and pistons regarding leakage . . . Fairly tight

Data and Results of Feed- Water Test.

Character of steam . . . . . 1 . ; Superheated 59°

Duration 5.63 hrs.

Weight of feed -water consumed 74,247 Ibs.

Feed-water consumed per hour 13,187 Ibs.

Pressure in steam pipe above atmosphere 77.6 Ibs.

Vacuum in condenser 27.9 in.

Mean effective pressure 40.49 Ibs.

Revolutions per minute 61

Indicated horse-power 615.1 I.H.P.

Feed-water consumed per I. H. P. per hour 21.44 Ibs.

Measurements Based on Sample Diagrams.

CONDENSING
CYLINDER.

NON-
CONDENSING
CYLINDER.

Initial pressure above atmosphere . . . Ibs.

Cut-off pressure above zero Ibs.

Release pressure above zero Ibs.

Mean effective pressure Ibs.

Back pressure at mid stroke, above or be-
low atmosphere Ibs.

Proportion of stroke completed at cut-off .
Steam accounted for at cut-off .... Ibs.
Steam accounted for at release .... Ibs.
Proportion accounted for at cut-off
Proportion accounted for at release . . .

76.7
80.4
20.3
45.33

11.9

.264
16.62
15.93

.895

.874

73.2
80.1
23.6
36.05

+ 2.6

.298
22.41
22.29

Engine No. 15 has a pair of cylinders provided with a jet-
condenser and direct connected air-pump. The exhaust piping
is arranged so as to run one cylinder condensing and the other

82

ENGINE No.

non-condensing, as was done on the test. Steam is supplied
from vertical superheating boilers. A small quantity of steam
was drawn from the boilers and used for other purposes than
running the engine ; but the quantity is insignificant, and no
allowance is made for it. The steam valves and pistons of
both cylinders were practically tight. There was a slight
amount of leakage in all the exhaust valves. The engine was
employed in driving a cotton-mill.

A test was made on this engine to determine the amount of
power used by the air-pump, which had a vertical plunger 22
in. diameter and 12-in. stroke. The connecting-rod on the
condensing side was disconnected, and cards were taken from
the other cylinder first with air-pump in operation and then
with air-pump stopped. The load driven in both cases was
the shafting of the mill. The difference in the two results
was 10.8 horse-power, or 1.8% of the working power of the
engine.

Sample indicator diagrams from the pump cylinder are ap-
pended, the first taken under the working conditions, and the
second obtained on the power test.

ENGINE No. 15 AIR PUMP

Working Conditions

—20

— 10
- O

— 10

Power Test

— 10

— 0

— 10

ENGINE No. 15

R,H. Cyl. Head End

-60

-40

-20

R.H. Cyl. Crank End

- 0

-10

—60

—40

—20

ENGINE No. 16.

Simple Non-Condensing Engine.

Kind of engine Single valve

Number of cylinders 2

Diameter of each cylinder 9.5 in.

Diameter of each indicator rod 375 in.

Stroke of each piston 9 in.

Clearance 14.1 %

H. P. constant for 1 Ib. m. e. p. one revolution per inin. . . .00322 H.P.

Inside diameter of steam pipe 3£ in.

Inside diameter of exhaust pipe 3£ in.

Condition of valves and pistons regarding leakage Some leakage

Data and Results of Feed - Water Tests.

LETTER BY WHICH TESTS ABE DESIGNATED

A.

B.

C.

Character of steam

Ordinary

Ordinary

Ordinary

Duration hrs.

2.908

2.983

3.067

Weight of feed-water consumed . Ibs.

4,248.3

3,451.9

2,854.76

Feed-water consumed per hour . Ibs.

1,460.9

1,157.2

930.8

Pressure in steam pipe above

atmosphere Ibs.

91 7

92.5

92.1

Mean effective pressure . . . Ibs.

39.49

30.76

22.33

Revolutions per minute ...

352.2

353.9

356.7

Indicated horse-power . . , .I.H.P.

44.81

35.08

25.66

Feed-water consumed per I. H. P.

per hour Ibs.

32.6

32.99

36.27

Measurements based on Sample Diagrams.

LETTER BY WHICH TESTS ARE DESIGNATED

A.

B.

C.

Initial pressure above atmosphere Ibs.
Cut-off pressure above zero . . Ibs.
Release pressure above zero . . Ibs.
Mean effective pressure . . . Ibs.
Back pressure at mid stroke above
atmosphere Ibs.
Proportion of stroke completed
at cut-off

84.7
79.1
38.3
39.57

+ 2.1
.353

85.3
77.1
33.8
30.55

+2.8
.278

82.7
76.4
30.6
22.29

+4.
.206

Steam accounted for at cut-off . Ibs.
Steam accounted for at release . Ibs.
Proportion accounted for at cut-
off
Proportion accounted for at re- .
lease . . . . . . . -. ""*".

22.92
23.27

.703
.714

21.51

22.89

/ .652
.694

19.92

24.07

.549
.664

Engine No. 16 has a pair of vertical, single-acting cylinders
with working parts inclosed in a chamber partly filled with oil.
The valve, which is common to both cylinders, is of the piston

85

86

ENGINE TESTS.

type with ring packing. Steam is supplied by a vertical boiler
having only a small amount of steam-heating surface. At a
point near the throttle valve a calorimeter test showed the
presence of 3% of moisture, no allowance for which is made
in the record of results. The pistons were practically tight.
The valve leaked a small amount. The load consisted of a
Prony brake applied to the fly-wheel.

The tests were three in number, made with different loads.

In these tests it appears that the economy of the engine was
not materially affected by reducing the load from 44.81 H. P.
to 35.08 H. P. A further reduction, however, increased the
consumption.

In connection with this series of tests, experiments were
made on the effect of a reduction of speed. It was found that
with a speed of 201.1 revolutions per minute, the steam con-
sumption per horse power per hour was increased 10 per cent.

ENGINE No. IGa

R.H.Cyl.

ENGINE No. 16b

R.H.Cyl.

80-
60-
40-
20-

0-
80
GO
40
20

0-

ENGINE No. 16c

R.H.Cyl.

L.H.Cyl.

ENGINE No. 17,

Simple Condensing Engine.

Kind of engine

Number of cylinders

Diameter of each cylinder

Diameter of piston-rod

Stroke of piston

Clearance

H.P. Constant for one Ib. m.e.p. one rev. per min. .
Condition of valves and pistons regarding leakage .

Four valve

1
18 ins.

2| ins.
30 ins.

5 %

.031 H.P.
Fairly tight

Data and Eesults of Feed -Water Tests.

CONDITIONS REGARDING USE OF
TEST.

CONDENSER.

CONDENSING.
A.

NON-
CONDENSING.
B.

Character of steam ....
Duration

. . hrs.

Ordinary
4 1

Ordinary
4

Weight of feed-water consumed
Feed-water consumed per hour
Pressure in steam pipe above
phere

. . . Ibs.
. . . Ibs.
atmos-
Ibs

19.298.
4,707.

67

24,201.
6,050.2

67 6

Vacuum in condenser

ins

25 5

Mean effective pressure

Ibs.

33 75

33 34

Kev per min

165 6

164 4

Indicated horse-power .

. . I.H.P.

213.2

209 1

Feed-water consumed per I. H.P

per hour Ibs.

22.08

28.93

Measurements Based on Sample Diagrams.

CONDITIONS REGARDING USE OF CONDENSER.
TEST.

CONDENSING
A.

NON-
CONDENSING
B.

Cut-off pressure above zero Ibs.

62.1

64.5

Release pressure above zero Ibs.

18.0

28.2

Mean effective pressure Ibs.

33.99

33.75

Back pressure at mid stroke, above or

below atmosphere Ibs.

—10.3

+1.5

Proportion of stroke completed at cut-off

.264

.385

Steam accounted for at cut-off . . . Ibs.

17.11

23.75

Steam accounted for at release . . . Ibs.

17.5

23.54

Proportion accounted for at cut-off

(average of two ends)

.77

.82

Proportion accounted for at release . Ibs.

.79

.81

Engine No. 17 has balanced slide valves. The condenser is
of the siphon pattern supplied with injection water under a
natural head. Steam is taken from return tubular boilers, and
it is presumed to be commercially dry. The valves were prac-

88

ENGINE No. 17.

89

tically tight, but the pistons showed a small amount of leakage.
The load was cotton machinery.

Two tests were made, one with the condenser in operation,
and the other with the engine exhausting into the atmosphere.

From these figures it appears that the use of the condenser
secured a reduction in the weight of steam consumed amounts
ing to 24%. This comparison is made under conditions of a
comparatively low boiler pressure.

OF THK

UNIVERSITY

ENGINE No. 17a

Head End

ENGINE No. 17b

60-

40-

20-

O-1

Head End

60-

40

20-

Crank End

ENGINE No. 18.

Simple Condensing Engine.
Kind of engine Four valve (Corliss)

... 2

... 20i ins.

... 3 ins.

... 4 ft.

... 3.4 %

. . . .0772
6 ins.

Condition of valves and pistons regarding leakage Fairly tight

Data and Results of Feed -Water Tests, Engine No. 18.

Number of cylinders

Diameter of each cylinder .

Diameter of each piston rod .........

Stroke of each piston

Clearance

H.P. Constant for one Ib. m.e.p., one rev. per minute
Inside diameter of steam pipe

TEST.
CYLINDERS IN USE.

A.

ONE.

B.
BOTH.

Character of steam .

Ordinary

Ordinary

Duration

hrs.

5.867

5.844

Weight of feed-water consumed ....
Feed-water consumed per hour ....
Pressure in steam pipe above atmosphere .
Vacuum in condenser . . .

Ibs.
Ibs.
Ibs.
ins.

24,310.
4,143.5

84.5

26.4

25,045.
4,285.6
59.
25.9

Mean effective pressure
Revolutions per minute

Ibs.

43.2
61.16

21.84
61.8

Indicated horse-power I
Feed-water consumed per I. H.P. per hour

H.P.

Ibs.

204.02
20.31

208.45
20.56

Measurements based on Sample Diagrams.

TEST.
CYLINDERS IN USE.

A.
ONE.

B.
BOTH.

Initial pressure above atmosphere . . .

Ibs.

82.7

56.8

Steam-pipe pressure above atmosphere .

Ibs.

85.3

60.5

Cut-off pressure above zero ......

Ibs

89.3

64.9

Release pressure above zero

Ibs.

18.0

8.7

Mean effective pressure . ...

Ibs.

42.51

21.72

Back pres. at mid stroke below atmosphere .

Ibs.

— 11.7

—11.9

Proportion of stroke completed at cut-off .

.188

.111

Steam accounted for at cut-off ....

Ibs.

14.73

13.73

Steam accounted for at release ....

Ibs.

14.8

14.61

Proportion accounted for at cut-off .

.725

.668

Proportion accounted for at release . . .

.729

.711

Engine No. 18 has a pair of cylinders with a jet condenser
operated by a direct connected air-pump. Steam is furnished
by return tubular boilers, and calorimeter tests showed that the

91

92 ENGINE TESTS.

percentage of moisture varied from -J- to 1 per cent. The
steam valves were fairly tight. The piston and exhaust
valves of one cylinder were absolutely tight. Those of the
other cylinder leaked a trifle. The load consisted of cotton
machinery.

Two tests were made, one with both cylinders in operation
and the other with a single cylinder, and in both the load was
practically the same. The tests were made with different
boiler pressures.

In this case it appears that the economy of feed-water con-
sumption was practically the same whether one cylinder was
used or the whole engine. As would be expected, however,
the proportion of steam accounted for by the indicator was the
least in the case of the earlier expansion.

In a series of experiments, of which these formed a part, a
test was made to determine the effect of increasing the boiler
pressure 20 Ibs. above the normal, one cylinder being in use.
In one case the pressure was 85.8 Ibs., and in the other 105.7 ;
and the mean effective pressure was, in round numbers, 41 Ibs.
in both cases. The cut-off occurred at TVo of the stroke in
one, and y1^ of the stroke in the other. The steam consump-
tion with the high pressure was 19.5 Ibs. per I. H. P. per hour,
and with the low pressure 19.2. In other words, there was a
trifling loss due to the increase of pressure. This engine was
not absolutely tight, and doubtless leakage affected the results,
so that the advantage of the increase of pressure was to some
extent counteracted.

On the last mentioned test the steam accounted for was .67.

ENGINE No. 18a

80-,
60-
40-
20-
0

Head End

80-
60-
40-
20

0-
10-

Crank End

UNIVERSITY

ENGINE No. 18b

R.H. Cyl. Head End

R.H, Cyl. Crank End

-60
-40
-20

- 0
-10

r-60
-40
-20

— 0

-10

60-
40-
20-

0-
10-

L.H. Cyl. Head End

60 -,
40-
20-

0-
10-

L.H. Cyl. Crank End

ENGINE No. 19.

Simple Condensing Engine.

Kind of engine Single Valve

Number of cylinders ...» 1

Diameter of cylinder . . . . . , 18.5 in.

Diameter of piston rod . . . 2i in.

Stroke of piston ".•'•.• '• . . . . > . 30. in.

Clearance ...... 7.5 %

H. P. Constant for one Ib. in. e. p. one rev. per minute . . .0405 H.P.

Condition of valves and pistons regarding leakage Some leakage

Data and Eesults of Feed -Water Test.

Character of steam . . . Ordinary

Duration . . . . . 5.011 hrs.

Weight of feed-water consumed - ... . . . 27,838.1 Ibs.

Feed-water consumed per hour . . . ... . , .. V 5,555.4 Ibs.

Pressure in steam pipe above atmosphere ' -. . 74.5 Ibs.

Vacuum in condenser . 24.8 ins.

Mean effective pressure . . . . . 39.05 Ibs.

Revolutions per minute .... . . . . . . . . 129.33

Indicated horse-power . . ... ... . . . . . 204.59 H.P.

Feed-water consumed per I. H. P. per hour 27.15 Ibs.

Measurements based on Sample Diagrams.

Initial pressure above atmosphere 69.3 Ibs.

Steam-pipe pressure 73.2 Ibs.

Cut-off pressure above zero . . . . . . ..... 66.8 Ibs.

Release pressure above zero 29.0 Ibs.

Mean effective pressure . . 38.1 Ibs.

Back pressure at mid stroke, below atmosphere .... — 8.9 Ibs.

Proportion of stroke complete at cut-off ....... .303

Steam accounted for at cut-off . . . . . . . . . . 19.17 Ibs.

Steam accounted for at release . 18.97 Ibs.

Proportion accounted for at cut-off ......... . 706

Proportion accounted for at release :.: . 699

Engine No. 19 has a single unpacked piston valve, controlled
by a shaft governor. The engine is provided with a jet con-
denser operated by an independent air-pump, driven by steam.
The steam used by the condenser was determined separately,
and allowance made for it in the record. Steam is supplied by
horizontal return tubular boilers, and it is presumed that it was
in a commercially dry condition. The piston of the engine
was tight, but the valve placed at the middle of its throw
showed considerable leakage. The load was cotton machinery.

95

ENGINE No. 19

Head End

60
-40
-20

- 0
-10

-60
-40
-20

0

- 10

ENGINE No. 2O.

Simple Condensing.

Kind of engine

Number of cylinders

Diameter of each cylinder . .

Diameter of each piston rod

Stroke of each piston

Clearance

H.P. constant for one Ib. in.e.p. one rev. per minute .

Inside diameter of steam pipe

Inside diameter of exhaust pipe

2

28
4
5
3

Four valve

ins.

ins.
ft.

Condition of valves and pistons regarding leakage .

Data and Results of Feed- Water Tests.

.3694 H.P.

9 ins.

10 ins.

Some leakage

TEST.
CONDITIONS REGARDING USE OF CONDENSER.

A.

CONDENSING.

B.
NON-
CONDENSING.

Character of steam . . . . . . . .

Ordinary.

Ordinary

Duration .

hrs.

10.08

9.83

Weight of feed-water consumed ....

Ibs.

102,947.

133,925.

Feed-water consumed per hour ....

Ibs.

10,213.

13,620.

Pressure in steam pipe above atmosphere .

Ibs.

68.1

65.1

Vacuum in condenser

ins.

23.

Mean effective pressure

Ibs.

23.12

23.81

Revolutions per minute

52.

50 5

Indicated horse-power I

H.P.

444.

451.6

Feed-water consumed per I. H.P. per hour

Ibs.

23.

30.16

Measurements based on Sample Diagrams.

TEST.
CONDITIONS REGARDING USE OF CONDENSER

.

A.

CONDENSING

B.
NON-
CONDENSING.

Initial pressure above atmosphere
Steam-pipe pressure
Cut-off pressure above zero
Release pressure above zero
Mean effective pressure

Ibs.
Ibs.
Ibs.
Ibs.
Ibs

63.6
68.1
71.2
9.5
23 25

62.5
65.7
70.1
16.8
23 97

Back pressure at mid stroke, above or be-
low atmosphere .

Ibs

11 1

-1-1 5

Proportion of stroke completed at cut-off .
Steam accounted for at cut-off ....
Steam accounted for at release ....
Proportion accounted for at cut-off
Proportion accounted for at release. . .

Ibs.
Ibs.

.119
14.13
14.37
.615

.625

.222

21.8
23.17

.722
.766

Engine No. 20 has a pair of cylinders with gridiron unbal-
anced slide valves. It is fitted with a jet condenser, operated

97

98 ENGINE TESTS.

by an independent air-pump driven by steam. The engine \vas
supplied from horizontal return tubular boilers, and the steam
on subsequent occasions was found to contain 1.2 °}0 of moisture.
In the matter of leakage, the engine was in fair condition,
though every valve, and the pistons as well, showed a small
amount of leakage. The load was made up largely of rubber
grinding machinery.

Two tests were made, one with the condenser in operation,
and the other with the engine exhausting into the atmosphere,
the condenser being stopped. Independent tests were made,
showing the quantity of steam used by the air-pump ; and
allowance has been made for it. Besides the engine, the boiler
supplied the feed-pump and a tank-pump, The steam thus
used has not been allowed for.

The air-pump, which had a single steam cylinder 16" in diam-
eter and 24" stroke, when making 56.3 single strokes per
minute, was found to use 1682 Ibs. of steam per hour. The
power developed amounted to 12.8 H. P. ; consequently the
air-pump consumed 131.7 Ibs. of steam per I. H. P. per hour.
On the condensing test the air-pump used over 13 per cent of
the entire quantity consumed by the engine.

The quantity of steam used by the engine and air-pump
working condensing was about 12 °/0 less than that used when
the engine was running non-condensing, and the quantity used
by the engine alone about 24 °fc less.

In explanation of the comparatively low proportion of feed-
water accounted for on the condensing test, it is probable that
allowance made for steam used by the condenser was less than
the actual quantity, owing to the fact that ordinarily the
cylinder drips were kept partially open. On the condenser
test, these were closed. Probably the actual consumption of
feed-water was somewhat below the 23 Ibs. given in the table,
and the actual proportions referred to were somewhat higher.
It should also be noted that the portion unaccounted for in-
cludes the steam used by the boiler-feed and tank-pump on both
tests, probably 2 or 3 % of the whole.

ENGINE No. 2Oa

60-
40-
20-

0-
10-

60-
40-
20-

0-
10-

L,H.Cyl. Head End

-60
-40
-20

- 0
-10

-60
-40
-20

- 0
-10

ENGINE No. 2Ob

60-

40

20-

RH.Cyl. Head End

60-

40-

20

0-1

RH.Cyl. Crank End

— 60

L.H.Cyl. Head End

-40

20

L- 0

-60

L.H.Cyl. Crank End

-40

-20

L 0

ENGINE No. 21.

Simple Non- Condensing Engine.

Kind of engine ...... ...... Four valve

Number of cylinders ..... .,.,... 1

Diameter of cylinder . . " ... . 11$ ins.

Diameter of piston rod ..... ..... II ins.

Stroke of piston . .... ..:.'.......'. 20 ins.

Clearance .-....' ... . . . '... . 10 %

H. P. constant for one Ib. m. e. p. one revolution per min. .0104 H.P.

Inside diameter of steam pipe ....../,.. 4 in.

Condition of valves and piston regarding leakage . . . Considerable leakage

Data and Results of Feed-Water Test.

Character of steam . . , . . . . .... . . . Superheated 4°

Duration . . 8 hrs.

Weight of feed-water consumed 10,341 Ibs.

Feed-water consumed per hour , . . . . 1,292 Ibs.

Pressure in steam pipe above atmosphere 64.5 Ibs.

Mean effective pressure 15.7 Ibs.

Revolutions per minute 198.3

Indicated horse-power ...... 32.26I.H.P.

Feed-water consumed per I. H. P. per hour 40.04 Ibs.

Measurements based on Sample Diagrams.

Initial pressure above atmosphere 63.1 Ibs.

Corresponding steam-pipe pressure 67 Ibs.

Cut-off pressure above zero 60.4 Ibs.

Release pressure above zero 22.4 Ibs.

Mean effective pressure 15.4 Ibs.

Back pressure at mid stroke, above atmosphere . 2 Ibs.

Proportion of stroke completed at cut-off . . . « .••""'. . . . .238

Steam accounted for at cut-off 24.85 Ibs.

Steam accounted for at release 25.13 Ibs.

Proportion of feed-water accounted for at cut-off . . . , . . . .62

Proportion of feed-water accounted for at release .627

Engine No. 21 has balanced slide valves. Steam is furnished
from a horizontal return tubular boiler of special design, which
is provided with a considerable amount of steam-heating sur-
face. The steam was superheated at the boiler 30°, and at a
point near the engine 4°. One of the exhaust valves and the
piston were fairly tight. The other steam valve and the other

101

102

ENGINE TESTS.

exhaust valve leaked very badly. The load consisted of a
dynamo furnishing a steady current for electric lighting.

It is evident that leakage of the valves referred to had much
to do with the poor showing.

ENGINE No. 21

80^
60-
40-
20-
0-

HeadEnd

Crank End

r— 80
-60
-40
-20
— 0

ENGINE No. 22.

Simple Condensing Engine.

Kind of engine . Four valve

Number of cylinders ................ 1

Diameter of cylinder .... , . M& ins.

Diameter of piston rod .... 5 ins.

Stroke of piston 5 ft.

Clearance ..... 2

H.P. constant for one Ib. m. e. p. one rev. per min 2791H.P.

Inside diameter of steam pipe . . . ....... . . . 14 ins.

Inside diameter of exhaust pipe 14 ins.

Condition of valves and piston regarding leakage Some leakage

Data and Results of Feed- Water Test.

Character of steam ....

Duration ........

Weight of feed-water consumed
Feed-water consumed per hour
Pressure in steam-pipe ...
Vacuum in condenser
Mean effective pressure .
Revolutions per minute . , .
Indicated horse-power . .
Feed- water consumed per I. H. P

Ordinary

.... 60,879

Ibs.

. , . . 11,343

Ibs.

82.3

Ibs.

. . . ;. 27.9

ins.

. . . . 37.23

Ibs.

...... 59.9

613.4 I

H.P.

per hour

18.49 Ibs.

Measurements based on Sample Diagrams.
Initial pressure above atmosphere .........

Corresponding steam-pipe pressure ........ .

Cut-off pressure above zero .... .......

Release pressure above zero ....... . .'.'..

Mean effective pressure . . . . . . ....,«,.,-,

Back pressure at mid stroke above or below atmosphere .
Proportion of stroke completed at cut-off .......

Steam accounted for at cut-off ..........

Steam accounted for at release ....... .

Proportion of feed-water accounted for at cut-off ....

Proportion of feed-water accounted for at release ....

81.9

84.2

75.6

15.5

37.17

13.6

.172

12.39 Ibs
13.41 Ibs

.669

.725

Ibs.
ibs.
Ibs.
Ibs.

Ibs.
Ibs.

Engine No. 22 has slide valves of the gridiron type. It is
provided with a siphon condenser, the injection water for which
is furnished under natural head. Steam is supplied to the
engine from water tube boilers through a 16-inch pipe 331 feet
in length. At a point near the engine it is drained by means
of a trap, which discharges to waste. On the test 143 Ibs. of
water were discharged per hour, and no allowance has been made

103

104

ENGINE TESTS.

for this. At a point between the trap and the engine the steam
was found by calorimeter test to contain 2^ per cent of mois-
ture. The exhaust valves were practically tight. The steam
valves and pistons showed some leakage. The engine worked
in connection with a water-wheel driving cotton machinery.

In examining the results of this test, which in view of the
long distance which the steam had to travel between the boil-
ers and the engine, shows excellent economy, the part which
the vacuum played cannot be overlooked. This was phenomi-
nally low, the back pressure at the middle of the stroke being
only about one pound above a perfect vacuum.

ENGINE No. 22

Head End

Crank End

C

-80
-60
-40
-20

- 0
-10

QO

60

40

-20

- 0

-10

ENGINE No. 23.

I A

Simple Non- Condensing Engine.

Kind of engine . "._ Single valve

Number of cylinders ... ..... 1

Diameter of cylinder ,.

Diameter of piston rod

Stroke of piston '.-.'.-.- 12

Clearance

H. P. constant for 1 Ib. m. e. p. one revolution per min.

Inside diameter of steam pipe

Inside diameter of exhaust pipe

Condition of valves and piston regarding leakage ....

ins.
ins.
ins.
14 %

.00301 H.P.
3 ins.

3£ ins.

Fairly tight

Data and Results of Feed -Water Tests.

TESTS.

A.

B.

C.

Character of steam
Duration hrs.
Weight of feed-water consumed . Ibs.
Feed-water consumed per hour . Ibs.
Pressure in steam pipe above
atmosphere Ibs.
Mean effective pressure . . . Ibs.
Revolutions per minute
Indicated horse-power . . . I.H P

Ordinary
3
2,140
713.3

83
24.53
303.7
22.45

Ordinary
4
4,035

1,008.8

82.4
34.86
307.8
32 33

Ordinary
4
4,833
1,208.2

81.9
42.99
304.5
39 44

Feed-water consumed per I. H. P.
per hour Ibs.

31.78

31.2

30.63

Measurements based on Sample Diagrams.

TESTS.

A.

B.

C.

Initial pressure above atmosphere Ibs.
Corresponding steam-pipe pressure Ibs.
Cut-off pressure above zero . . Ibs.
Release pressure above zero . . Ibs.
Mean effective pressure . . . Ibs.
Back pressure at mid stroke above
atmosphere Ibs.
Proportion of stroke completed
at cut-off

78.8
83
76.2
27.4
24.61

.8
203

77.3
82
75.5
32.5
34.79

.7
312

79.5
81.8
78.1 '
37.3
43.12

.7
378

Steam accounted for at cut-off . Ibs.
Steam accounted for at release . Ibs.
Proportion of feed water account-
ed for at cut-off ....
Proportion of feed water account-
ed for at release ...

20.4
21.66

.642

.681

22.48
21.76

.72
.698

23.33
22.24

.762
.726

Engine No. 23 has a single-slide valve which is balanced by
means of a pressure-plate riding on the back, and the cut-off is

105

106

ENGINE TESTS.

made automatic through the action of a shaft governor. Steam
is supplied from a horizontal return tubular boiler. A calorim-
eter test showed that it was practically dry. The piston was
fairly tight. The valve showed some leakage. The load con-
sisted of a Sturtevant Blower. A series of tests were made
under conditions of different loads, but practically constant
boiler pressure.

Another test in the same series with a load of 28.44 I. H. P.,
which is intermediate between the first and the second, gave a
feed-water consumption of 31.46 Ibs. per I. H. P. per hour, and
the proportions of steam accounted for were respectively .685
and .694. In this series of tests the gradual improvement in
the economy as the load is increased is a noticeable feature, as
is also the uniform increase in the proportion of steam ac-
counted for at the cut-off. Another point to be noticed is that
as the cut-off becomes later, the amount of steam present at the
release compared with that at cut-off is gradually reduced. In
the first experiment the steam at release is the greater of the
two, while in the last it is the smaller.

80-, |\ ENGINE No. 23a

60-

40-

20-

0-
80^

60-

40-

20-

Head End

Crank End

ENGINE No.23b

40

20

Head End

0—

ENGINE No. 24.

Simple Non- Condensing Engine.

Kind of engine . . . . . ... ,, Single valve

Number of cylinders ......... .^ ... I

Diameter of cylinder ...',... 14.5 ins.

Diameter of piston rod ............ 2£ ins.

Stroke of piston .... . . ..' . . . , ' •. . . . 13 ins.

Clearance - . . . . 12 %

H. P. constant for 1 Ib. in. e. p. one revolution per min. .0107 HP.

Inside diameter of steam pipe 5 ins.

Condition of valves and piston regarding leakage . . . Fairly tight

Data and Results of Feed- Water Test

Character of steam Ordinary

Duration (, 4.45 hrs.

Weight of feed-water consumed '. " ' . 8,983 Ibs.

Feed-water consumed per hour 2,018.6 Ibs.

Pressure in steam pipe above atmosphere 80.3 Ibs.

Mean effective pressure 23.22 Ibs.

Revolutions per minute 248.4

Indicated horse-power '; 61.7 I.H.P.

Feed-water consumed per I. H. P. per hour 32.71 Ibs.

Measurements based on Sample Diagrams.

Initial pressure above atmosphere ... . 78.4 Ibs.

Corresponding steam-pipe pressure 80.5 Ibs.

Cut-off pressure above zero . ... . . .....•• ... . 74.1 Ibs.

Release pressure above zero 29.6 Ibs.

Mean effective pressure • » . . 23.43 Ibs.

Back pressure at mid stroke above atmosphere 2.6 Ibs.

Proportion of stroke completed at cut-off .211

Steam accounted for at cut-off 21.66 Ibs.

Steam accounted for at release 23.57 Ibs.

Proportion of feed-water accounted for at cut-off .662

Proportion of feed-water accounted for at release .721

Engine No. 24 is of the high-speed type, with an unpacked
piston valve controlled by a shaft governor. Steam was sup-
plied from a horizontal return tubular boiler in what was
believed to be a commercially dry state. The valve was new,
well fitted, and fairly tight. The piston was also fairly tight.
The load consisted mainly of machinery for the manufacture of
woolen yarns.

108

ENGINE No. 24

Head End

1—80

— 60

-40

- 20

L- 0

Crank End

r- 80

- 60

-40

-20

L- 0

ENGINE No. 25.

Simple Condensing Engine.

Kind of engine *. . Four valve (Corliss)

Number of cylinders . . . . . . . . • -. . . . ... . 2

Diameter of each cylinder . . . . . . . , . . , ; .26 ins.

Diameter of each piston rod . . . . . . ~ . . . . . . 3| ins.

Stroke of each piston . . . . . . '.-.-. 5 ft.

Clearance •...-...-. . . ~. 3 %

H. P. constant for one Ib. m. e. p. one revolution per minute

each cylinder .16 H.P.

Inside diameter of steam pipe 8 ins.

Inside diameter of exhaust pipe 10 ins.

Condition of valves and pistons regarding leakage Some leakage

Data and Results of Feed Water Test.

Character of steam Ordinary

Duration '.. . . . 1.75 hrs.

AVeight of feed-water consumed 24,416 Ibs.

Feed-water consumed per hour 13,948 Ibs.

Pressure in steam pipe above atmosphere 82.9 Ibs.

Vacuum in condenser 25.9 ins.

Mean effective pressure 36.29 Ibs.

Revolutions per minute 53.9

Indicated horse-power 625.6 I. H.P.

Feed-water consumed per I. H. P. per hour 22.29 Ibs.

Measurements Based on Sample Diagrams.

THREE ENDS
CONDENSING.

ONE END

NON-
CONDENSING.

Initial pressure above atmosphere . . . Ibs.

Corresponding steam-pipe pressure . . . Ibs.

Cut-off pressure above zero Ibs.

Release pressure above zero Ibs.

Mean effective pressure Ibs.

Back pressure at mid stroke, above or be-
low atmosphere Ibs.

Proportion of stroke completed at cut-off .

Steam accounted for at cut-off .... Ibs.

Steam accounted for at release .... Ibs.

Proportion of feed-water accounted for at
cut-off, average

Proportion of feed-water accounted for at
release, average. . ." . . . . .

79.9
83.4
73.2
19.2
40.25

10.

.245
15.49
15.59

79.7
83.4
66.2
17.6
23.94

+ 3.5

.24
21.17
22.23

.737
.740

Engine No. 25 has a pair of horizontal cylinders exhausting
into a jet condenser which is operated by a direct connected

110

ENGINE No. 25.

air-pump. The cylinders were arranged for running one end
of one cylinder non-condensing, and it was under these condi-
tions that the tests were made. Steam is furnished by cylinder
boilers, and it is presumed that it was in a commercially dry
condition. When the water was carried at an unusually low
point, a small portion of the shell became steam-heating sur-
face, and the steam was found to be slightly superheated. Two
of the steam valves- showed some leakage. The pistons also
leaked a small amount. The remaining valves were fairly
tight. The load consisted of cotton machinery.

ENGINE No. 25

RH.Cyl. Head End

r80

-60

-40

20

ENGINE No. 26.

Simple Non-Condensing Engine.

Kind of engine Four valve

Number of cylinders 1

Diameter of cylinder 16j

Diameter of piston rod 21

Stroke of piston 3

Clearance 6 %

H.P. Constant for one Ib. m.e.p. one rev. per rnin 03717 H.P.

Condition of valves and piston regarding leakage .... Leakage Test A

Data and Results of Feed -Water Tests.

ins.

ins.

ft.

TEST.

A.

B.

Character of steam . .
Duration
Weight of feed-water consumed
Feed-water consumed per hour
Pressure in steam pipe above
phere

. hrs.
. . . Ibs.
. . . Ibs.
atmos-

Ihs

Ordinary
3.117
7,207.
2,312.2

74.2
25.17
75.8
70.9
32.61

Ordinary
3.
6,221.
2,073.7

74.
24.89
76.03
70.6
29.37

Mean effective pressure . . . Ibs.
Revolutions per minute
Indicated horse-power I. H.P.
Feed-water consumed per I. H.P. per hour, Ibs.

Measurements based on Sample Diagrams.

TEST.

A.

B.

Initial pressure above atmosphere

Ibs.

66.2

66.5

Corresponding steam-pipe pressure .

Ibs.

74.2

74.

Cut-off pressure above zero

Ibs.

64.7

65.5

Release pressure above zero

Ibs.

18.5

18.3

Mean effective pressure

Ibs.

25.17

24.89

Back pres. at mid stroke above atmosphere .

Ibs.

1.9

1.7

Proportion of stroke completed at cut-off .

.237

.223

Steam accounted for at cut-off ....

Ibs.

22.55

21.87

Steam accounted for at release ....

Ibs.

24.65

24.64

Proportion of feed-water accounted for at

cut-off

.692

.745

Proportion of feed-water accounted for at

release

.755

.839

Engine No. 26 has double poppet steam valves, and plain
slide exhaust valves. Steam is drawn from horizontal return
tubular boilers. The load was a machine shop. The valves
and piston were practically tight on test B. On test A the

113

114 ENGINE TESTS.

exhaust valve leaked badly, and during the interval between
the two it was repaired.

The effect of exhaust valve leakage on the economy of the
engine is here clearly revealed. The tighter engine used about
10% less steam. The effect of the leakage upon the lines of
the diagrams is hardly noticeable.

ENGINE No. 26a

60

40-

20-

60-

40-

20-

Crank End

60-

ENGINE No. 26b

40-

Heacl End

20-

40

20-

Crank End

ENGINE No. 27.

Simple Non-Condensing Engine.

Kind of engine Single valve

Number of cylinders " * 1

Diameter of cylinder . . . . . ... . . » . . . . 121 ins.

Diameter of piston rod . . . ..... 2? ins.

Stroke of piston 20 ins.

Clearance ....*....', V ... 8 %

H. P. constant for 1 Ib. in. e. p. one revolution per minute . . 01219 H. P.
Condition of valves and piston regarding leakage . . Considerable leakage

Data and Results of Feed-Water Test.

Character of steam . . . . . . . . . . . . .' . Ordinary

Duration. ... . . . . . . .' '.. . . . . . .' 3.083 hrs.

Weight of feed-water consumed . ... . . . . . . 4,374.5 Ibs.

Feed-water consumed per hour . . » .... ..." . 1,418.9 Ibs.

Pressure in steam pipe above atmosphere . . . . . . . 72.2 Ibs.

Mean effective pressure 18.15 Ibs.

Revolutions per minute . . . . . . .• . ... • • 172.3

Indicated horse-power . , . . . . . . 38.1 I.H.P.

Feed-water consumed per I. H. P. per hour . . . . -, . . 37.21 Ibs.

Measurements based on Sample Diagrams.

Initial pressure above atmosphere . . . ... . . . . . 68.8 Ibs.

Corresponding steam-pipe pressure . . ...... . . . 72.2 Ibs.

Cut-off pressure above zero ... . '. . . . ... . . . . 66.5 Ibs.

Release pressure above zero 26.4 Ibs.

Mean effective pressure \ . ... ... * . 18.15 Ibs.

Back pressure at mid stroke above atmosphere . . ..... . 3.5 Ibs.

Proportion of stroke completed at cut-off . . . ...... .219

Steam accounted for at cut-off .'. . . . . . . . . . . :. 21.13 Ibs.

Steam accounted for at release . . . ... . . . !. . . 26.74 Ibs.

Proportion of feed-water accounted for at cut-off . . . . . • -568

Proportion of feed-water accounted for at release . . . ... .719

Engine No. 27 is of the high-speed class, with unpacked
piston valve operated through a shaft governor. The boiler is
of the horizontal return tubular type. The leakage of the
engine was confined mainly to the valve. The load consisted
of machine tools.

The engine being located at a distance of some 75 ft. from
the boiler, the condition of the steam was not so favorable for
economy as it might otherwise have been. Doubtless this ex-
plains in part the poor showing.

116

ENGINE No. 27

Head End

-60

-40

-20

Crank End

- 60

40

-20

I— O

ENGINE No. 28.

Simple Condensing Engine.

Kind of engine . . - .... ... . . . . ." Four valve (Corliss)

Number of cylinders , 1

Diameter of cylinder 32i ins.

Diameter of piston rod 4£ ins.

Stroke of piston . . . . . . . -. . ..'... 5 ft.

Clearance ...."...... 2i %

H. P. Constant for one Ib. m.e.p., one rev. per minute . .2451 H.P.

Condition of valves and piston regarding leakage ... Some leakage

Data and Results of Feed - Water Test.

Character of steam Ordinary

Duration . . ...'.'.-..». . . . . . .... . 5.1 hrs.

Weight of feed-water consumed . . . , . ' 55,001 Ibs.

Feed-water consumed per hour . . ... . . . . . . 10,784.5 Ibs.

Pressure in steam pipe above atmosphere 70. 1 Ibs.

Vacuum in condenser . ...... . . . . . . . 24.2 ins.

Mean effective pressure . .; . . .• 38.26 Ibs.

Revolutions per minute ...... . . . . . . 59.13

Indicated horse-power . 554.4 I. H.P.

Feed-water consumed per I. H. P. per hour . . . . . . 19.45 Ibs.

Measurements based on Sample Diagrams.

Initial pressure above atmosphere . . . 67.5 Ibs.

Corresponding steam-pipe pressure .. \. .' 70.1 Ibs.

Cut-off pressure above zero . . . • . .61.5 Ibs.

Release pressure above zero . . . . .- . . . . . 17.6 Ibs.

Mean effective pressure . . . . . . . .' . . . . 38.26 Ibs.

Back pressure at mid stroke, below atmosphere . . . .11.6 Ibs.

Proportion of stroke completed at cut-off , . . . . . .271

Steam accounted for at cut-off .„ , » . . . . ' . . . 15.20 Ibs.

Steam accounted for at release . ..... . . • •• " • 15.27 Ibs.

Proportion of feed-water accounted for at cut-off . . . . . 4 .781

Proportion of feed-water accounted for at release . . . . .785

Engine No. 28 exhausts into a jet condenser, with direct
connected air-pump. The boilers are of the horizontal return
tubular type. The steam valves were practically tight. There
was some small amount of leakage of the piston, and a trifling
leakage of the exhaust valves. The load was cotton machinery.

118

ENGINE No. 28

Head End

-60

-40

-20

60-

40-

Crank End

20-

0-
10—

'^££SE L/S':?^^
OK THK **y-

UNIVERSITY

ENGINE No. 29.

Simple Condensing Engine.

Kind of engine

Number of cylinders - . .

Diameter of each cylinder ., . . .

Diameter of each piston rod . . .

Stroke of each piston . . '. . » ,

Clearance . . . . . . . . . • .••' «T • • • •

H. P. Constant for one Ib. in. e. p. one rev. per minute

Four valve (Corliss)
2

28 ins.

4 ins.

5 ft.
2* %

.1846 H.P.

Condition of valves and pistons regarding leakage Some leakage

Data and Results of Feed -Water Test.

R. H. L. H.
CYLINDER. CYLINDER.

Character of steam . . . ' . .

Ordinary

Duration

hrs.

5.32

Weight of feed- water consumed . .
Feed-water consumed per hour ....
Pressure in steam-pipe above atmosphere .
Vacuum in condenser

Ibs.
Ibs.
Ibs.
ins

76,053
14,295.7
67.1
27.3

Mean effective pressure .

Ibs.

19.26 31.26

Revolutions per minute . ... . . .
Indicated horse-power I

H.P.

60.27 60.27
214.3 347.8

Indicated horse-power, whole engine . I
Feed-water consumed per I. H. P. per hour

H.P.

Ibs.

562.1
25.43

Measurements Based on Sample Diagrams.

K. H. L. H.
CYLINDER CYLINDER.

Initial pressure above atmosphere . . .
Corresponding steam-pipe pressure .
Cut-off pressure above zero . .

Ibs.
Ibs.
Ibs

61.9 63.7
67.1
67 7 67.6

Release pressure above zero . . .
Mean effective pressure

Ibs.
Ibs.

16.6 13.9
19.26 31.26

Back pressure at mid stroke, above or be-
low atmosphere ... ....
Proportion of stroke completed at cut-off .
Steam accounted for at cut-off . v .. . ' •' .
Steam accounted for at release ....
Steam accounted for at cut-off, both cylin-
ders, average
Steam accounted for at release, both cylin-
ders, average
Proportion of feed-water accounted for at
cut-off

Ibs.

Ibs.
Ibs.

Ibs.
Ibs.

+2.8 —12.1
.202 .187
21.82 14.46
24.31 14.86

17.27
18.37
.679

Proportion of feed-water accounted for at
release

.722

120

ENGINE No. 29. 121

Engine No. 29 has a pair of cylinders, one of which is non-
condensing, and the other exhausts into a jet condenser with
direct connected air-pump. Steam is drawn from horizontal
return tubular boilers, and is presumably in a commercially dry
state. There was a small amount of leakage in the valves of
both cylinders, not only steam valves but exhaust valves, and
some piston leakage. The engine operated a cotton-mill, work-
ing in connection with water-wheels.

ENGINE No. 29

60-]

40-

20-

O-1

R.H.Cyl. Head End

—20

U o

-GO

L.H.Cyl. Head End

60-
40-
20-

0-
10-

L.H. Cyl. Crank End

-40

-20

- 0
-10

ENGINE No. SO.

Simple Condensing Engine.

Kind of engine . .... Four valve

Number of cylinders 2

Diameter of cylinder • . 16 ins.

Diameter of piston rod 2i ins.

Stroke of piston 3 ft.

Clearance 5 %

H. P. constant for one Ib. in. e. p. one rev. per min., each .0361 H.P.

Inside diameter of steam pipe . - 5 ins.

Inside diameter of exhaust pipe 6 ins.

Condition of valves and pistons regarding leakage . . Some leakage

Data and Results of Feed- Water Test.

Character of steam Ordinary

Duration 5. hrs.

Weight of feed-water consumed 22,055 Ibs.

Feed- water consumed per hour 4,411 Ibs.

Pressure in steam pipe above atmosphere 83.4 Ibs.

Vacuum in condenser 26.7 ins.

Mean effective pressure 31.27 Ibs.

Revolutions per minute 90.4

Indicated horse-power 205.9 I. H.P.

Feed- water consumed per I. H. P. per hour 21.42 Ibs.

Measurements based on Sample Diagrams.

Initial pressure above atmosphere 74.4 Ibc.

Cut-off pressure above zero 75.0 Ibs.

Release pressure above zero 14.9 Ibs.

Mean effective pressure 31.16 Ibs.

Back pressure at mid stroke below atmosphere — 11.15 Ibs.

Proportion of stroke completed at cut-off .139

Steam accounted for at cut-off 13.81 Ibs.

Steam accounted for at release 16.45 Ibs.

Proportion of feed-water accounted for at cut-off .645

Proportion of feed-water accounted for at release .761)

Engine No. 30 has a pair of cylinders each having two steam
valves and two exhaust valves, all being slide valves. The
condenser is of the jet type operated by an independent air-pump
driven by steam taken from the engine-pipe. The quantity of
steam used by the condenser was determined by an independent
test and allowed for. Steam is furnished by vertical water
tube boilers, and a separator is fitted to the main steam pipe.

123

124 ENGINE TESTS.

No water collected in the separator, and the steam is presumed
to be commercially dry. The valves and pistons of each cyl-
inder showed some leakage. The load consisted of dynamos
furnishing current for electric lighting.

Engine No. 30 belongs to the same plant as Nos. 35 and 36,
and it is supplied with steam from the same boiler plant.

ENGINE No. 3O

80-1

ENGINE No. 31.

Simple Non-Condensing Engine.

Kind of engine

Number of cylinders

Diameter of each cylinder

Diameter of each piston rod

Stroke of each piston

Clearance ........... 4 ....

H.P. constant for one Ib. m.e.p. one rev. per minute .
Inside diameter of steam pipe . . . % . . . . . .

Condition of valves and pistons regarding leakage .

Data and Results of Feed- Water Tests.

Four valve (Corliss)

O

ins.
ins.
ins.

16

21
42

2.5 %

.042 H.P.

7 ins.

Fairly tight

CHARACTER OF LOAD.

A.
LIGHT LOAD.

B.
HEAVY
LOAD.

Character of steam .... . ...-.•'.
Duration ... . . ' .

hrs

Ordinary
4

Ordinarv

2

AVeight of feed-water consumed . .
Feed-water consumed per hour . . ; .
Pressure in steam pipe above atmosphere .
Mean effective pressure . . . ... .
Revolutions per minute . .
Indicated horse-power . . ... I

Ibs.
Ibs.
Ibs.

Ibs.

H P

10,897.
2,724.2
101.8
5.03
87.6
37 02

17.746.
8,873.
98.6
48.4
84.9
342 43

Feed-water consumed per I. H.P. per hour

Ibs.

73.63

25.91

Measurements based on Sample Diagrams.

CHARACTER OF LOAD.

A.
LIGHT LOAD.

.

B.
HEAVY
LOAD.

Initial pressure above atmosphere . . .
Cut-off pressure above zero . . . .

Ibs.
Ibs

80.5
81.9

91.6

94.8

Release pressure above zero . . . . ...••
Mean effective pressure . ...
Back pres. at mid stroke above atmosphere .
Proportion of stroke completed at cut-off .
Steam accounted for at cut-off . . . " .; ;
Steam accounted for at release ....
Proportion of feed-water accounted for at
cut-off

Ibs.
Ibs.
Ibs.

Ibs.
Ibs.

5.4
2.

.041

28.16

.382

31.4
49.26
2.6
.323
20.63
21.55

.796

Proportion of feed-water accounted for at
release

.832

Engine No. 31 has a pair of cylinders drawing steam from
horizontal return tubular boilers. There was only a small
amount of leakage in any of the valves and pistons. The

126

ENGINE No. 31.

127

engine was employed in driving a line-shaft to which, were
belted dynamos supplying current for electric lighting.

The tests reported in the principal table were two in number,
one of which was made with a friction load consisting of the
shafting and empty dynamos, and the other with a full load.

Tests on the same engine at intermediate loads gave the fol-
lowing principal results :

INDICATED
HORSE
POWER.

FEED-WATER
PEK I.H.P.
PER HOUR.

PROPORTION
OF STROKE
COMPLETED
AT CUT-OFF.

PROPORTION
OF FEED-
WATER ACCT.
FOR AT CUT-
OFF.

100.4

38.38

.084

.509

146.2

31.43

.121

.588

222.2

25.83

.178

.709

287.1

25.39

.231

.745

ENGINE No. 31a.

RH.Cyl. Head End

L.H.Cyl.HeadEnd

L- 0

-100
-80
-60
40
-20
- 0

L.H.Cyl. Crank End

-60

40

-20

- 0

ENGINE No.Slb

L.H.Cyl.Head End

L.H.Cyl. Crank End

-80

-60

-40

-20

- 0
-80
-60
-40
-20

- O

FEED -WATER TESTS.

COMPOUND ENGINES.

[ These engines are all of the automatic cut-off type, with fly-ball governor,
unless otherwise stated.]

181

ENGINE No. 32.

Compound Condensing Engine.

H. P.
CYLINDER.

L. P.
CYLINDER.

Kind of engine

ins.
ins.
ft.

%

H.P.

ins.
ins.

Four valv
1
26
4
4
3

.159
1
8
14

Fairly tight

e (Corliss)
1
48
5
4
3

.5454
3.43
14
14

Tight

^Number of cylinders .

Diameter of cylinders . .-.•'.
Diameter of piston rod
Stroke of piston ....

Clearance

H. P. constant for 1 Ib. m. e. p. one rev-
olution per miu
Ratio of areas of cylinders
Inside diameter of steam pipe
Inside diameter of exhaust pipe ....
Condition of valves and pistons regarding
leakage

Data and Results of Feed -Water Test.

Character of steam . .-..;• . ., .

Duration . . . . . • . / t .

Weight of feed-water consumed .... . . . . .

Feed-water consumed per hour . . . .

Pressure in steam pipe above atmosphere . . . ....

Pressure in receiver . .

Vacuum in condenser

Revolutions per minute . . .

Mean effective pressure, H. P. cylinder

Mean effective pressure, L. P. cylinder

Indicated horse-power, H. P. cylinder

Indicated horse-power, L. P. cylinder

Indicated horse-power, whole engine

Feed-water consumed per I. H. P. per hour

Ordinary

4.5

hrs.

*44,436

Ibs.

9,874
94.8

Ibs.
Ibs.

6.4

Ibs.

27.2

ins.

52.3

41.14

Ibs.

9.27

Ibs.

342.1

H.P.

264.43

H.P.

606.53

H.P.

*16.28

Ibs.

Measurements based on Sample Diagrams.

H.P.
CYLINDER.

L. P.
CYLINDER.

Initial pressure above atmosphere .

Ibs.

89.4

6.0

Corresponding steam-pipe or receiver

pressure ... . .

Ibs.

94.2

6.3

Cut-off pressure above zero ....

Ibs.

91.9

12.6

Release pressure above zero ....

Ibs.

28.4

7.5

Mean effective pressure

Ibs.

41.26

9.28

Back pressure at mid stroke, above or

below atmosphere

Ibs.

+ 8.1

- 10.8

Proportion of stroke completed at cut-off

.305

.544

Steam accounted for at cut-off .

Ibs.

12.60

11.78

Steam accounted for at release .

Ibs.

12.84

12.98

Proportion of feed-water accounted for

at cut-off

.774

.723

Proportion of feed-water accounted for

at release

.789

.797

Includes steam used by circulating-pump.

133

134 ENGINE TESTS.

Engine No. 32 is a cross-compound, having unjacketed hori-
zontal cylinders 'and unjacketed receiver. A surface condenser
is employed, and the air-pump is operated by direct connection
with the engine. The circulating-pump is a duplex steam
pump 9" x 10" x 12", and the steam it used is included in that
reported. The engine is furnished with steam from sectional
boilers, and it is presumed to be in a commercially dry condi-
tion. In the matter of leakage the engine was in excellent
condition throughout with the exception of the piston in the
high-pressure cylinder, which leaked a small amount. The
load consisted of a cotton-mill. The feed-water consumption
was determined by measuring the water discharged by the air-
pump.

ENGINE No. 32

H.P. Head End

H,P. Crank End

— 100

— 80

— 60
-40

— 20
L— 0

r— 100

-80
—60

— 40
—20

— 0

5-
0-
5-
10-

L,P. Head End

5-

o-

5-
10-

L,P. Crank End

ENGINE No. 33.

Compound Condensing Engine.

\

H.P.
CYLINDER.

L. P.

CYLINDER.

Kind of engine . ... . .

Single

valve.

Number of cylinders . . ...

1

1

Diameter of cylinder .... ins.

12

20

Stroke of piston .... ins

12

12

Clearance %

33

9

H. P. Constant for one Ib. m. e. p.

one rev. per min H.P.

.00342

.00952

Ratio of areas of cylinders .

1

2.78

Condition of valves and pistons

regarding leakage ....

Tight.

Tight.

Data and Results of Feed -Water Tests.

TEST.
CONDITIONS REGARDING USE OF CONDENSER.

A.

CONDENSING

B.

NON-
CONDENSING

Character of steam

Ordinary

Ordinary

Duration hrs.

8

8

Weight of feed-water consumed . Ibs.

34,555

41,562

Feed-water consumed per hour . Ibs.

4,319.4

5,195

Press, in steam pipe above atmos. Ibs.

129.3

128

Vacuum in condenser .... ins.

25

Revolutions per minute ....

300.

296.1

Mean effective pressure, H.P. cyl. Ibs.

53.53

57.21

Mean effective pressure, L.P. cyl. Ibs.

20.73

20.34

Indicated horse-power, H.P. cyl. H.P.

109.84

115.85

Indicated horse-power, L. P. cyl. H.P.

118.41

114.69

Indicated H. P., whole engine . H.P.

228.25

230.54

Feed-water cons, per I. H.P. per hr. Ibs.

18.92

22.53

The above are the totals and averages for the two engines.
Measurements based on Sample Diagrams.

TESTS.

H.P.CYL.

L.P. CYL.

H.P.CYL.

L.P. CYL.

Initial pressure above atmosphere Ibs.

122.9

33.9

121.5

52.8

Corresponding steam -pipe pressure Ibs.

132.

136.

Cut-off pressure above zero . . Ibs.

122.

27.1

124.3

35.8

Release pressure above zero . . Ibs.

67.9

17.8

82.3

27.4

Mean effective pressure ... Ibs.

53.4

20.71

56.44

20.25

Back pressure at mid stroke above

i

or below atmosphere . . Ibs.

+ 20.3

—11. '+29.4

+ 1.1

Proportion of stroke completed

j ,. •

at cut-off

.38

.521] .532

.66

Steam accounted for at cut-off . Ibs.

15.21

12.14

20.13

16.54

Steam accounted for at release . Ibs.

16.24

1321

28.2

17.76

Proportion of feed water account-

ed for at cut-off . . .. .

.804

.642

.894

.734

Proportion of feed water account-

ed for at release . . . .

.859

.700

.925

.789

136

ENGINE No. 33. 137

Engine No. 33 consists of two independent engines which
w^ere tested simultaneously. These engines are single-acting
with vertical unjacketed cylinders, and provided with a single
piston valve fitted with ring packing, one valve serving for
both high- and low-pressure cylinders. A jet condenser is used
which is common to both engines ; and it is operated by an inde-
pendent air-pump, which takes steam from the main supply
pipe. The boiler feed-pump is also supplied from the main
pipe. The quantity of steam used by these two pumps was
determined by independent tests and allowed for. Steam is
furnished by water tube boilers ; and a calorimeter test showed
in one case ^ of 1 % of moisture, and in the other ITL % . The
valves and pistons of both engines were practically tight. The
load consisted of dynamos employed in electric lighting. One
test was made with the engines running condensing, and an-
other running non-condensing, the condenser being stopped.

The difference in economy of these engines, due to the use
of a condenser not allowing for steam used by air-pump, is
represented by 3.61 Ibs. of feed-water per I. H. P. per hour,
which, in round numbers, is 20 <% of the quantity used when
the engine was run condensing. The results of these tests can-
not be passed by without noticing the marked difference in the
porportion of steam accounted for at the cut-off under the two
conditions of operation ; and the loss of steam between the
high-pressure cylinder and low-pressure cylinder in both cases.

<P§6 L'BR^>

~ OF THK

UNIVERSITY

ENGINE No. 33a

H.P. 17

L.P. 17

— 120

- 30

— 40

0
— 40

— 20

— 0

— 10

120-

80-

40-

H.P. 24

, ENGINE No. 33b

H,P. 17

L.P. 17

i— 120

- 80

- 40

- 20

— 0

120—1

80-

40-

H.P. 24

40-

20-

L.P. 24

ENGINE No. 34.

Compound Condensing Engine.

H.P. CYLINDER.

L.P. CYLINDER.

Kind of engine . . .-,. . . . .
Number of cylinders , . . . . .
Diameter of cylinder

ins.
ins.
ft.

%

H.P.

ins.
ins.

Four valv
1
22
31
5
2.2

.1138
1

7
9

Some leakage

B (Corliss)
1
44
31
5
5.9

.4592
4.04
13
16
Practically
tight

Diameter of piston rod
Stroke of piston ....

Clearance

H. P. constant for one Ib. in. e. p. one
rev. per min
Ratio of areas of cylinders ....
Inside diameter of steam pipe . . .
Inside diameter of exhaust pipe . .
Condition of valves and pistons regard-
ing leakage

Data and Results of Feed - Water Test.

Character of steam

Duration

Weight of feed-water consumed . . .... . . . .

Feed-water consumed per hour . . . . . . . . .

Pressure in steam pipe above atmosphere . .....'. .".

Pressure in receiver above atmosphere

Vacuum in condenser . . . . . ; . i ... ... ,

Revolutions per minute ...

Mean effective pressure H. P. cylinder *,

Mean effective pressure L. P. cylinder . . . ... ,

Indicated horse-power H. P. cylinder , .

Indicated horse-power L. P. cylinder . . .v . . . . .,
Indicated horse-power, whole engine . . . „. . . .
Feed-water consumed per I. H. P. per hour . . .'-....,

Ordinary

4

hrs.

33,813

Ibs.

8,453.2

Ibs.

116.1

Ibs.

7.5

Ibs.

25.5

ins.

68.08

41.48

Ibs.

10.08

Ibs.

321.39

H.P.

315.09

H.P.

636.48

H.P.

13.28

Ibs.

Measurements based on Sample Diagrams.

H. P.
CYLINDER.

L.P.

CYLINDER.

Initial pressure above atmosphere . . Ibs.

108.8

9.1

Corresponding steam-pipe or receiver

pressure Ibs.

114.2

7.4

Cut-off pressure above zero . . . -". Ibs.

104.

16.7

Release pressure above zero . „ . ;. Ibs.

29.1

6.8

Mean effective pressure Ibs.

41.26

10.05

Back pressure at mid stroke above or

below atmosphere Ibs.

+ 11.3

- 11.8

Proportion of stroke completed at cut-off

.26

.325

Steam accounted for at cut-off . . . Ibs.

10.48

10.06

Steam accounted for at release . . . Ibs.

11.3

10.98

Proportion of feed-water accounted for

.789

.758

Proportion of feed-water accounted for

at release

.852

.827

140

ENGINE No. 34- 141

Engine No. 34 is a cross compound with horizontal jacketed
cylinders and uiijacketed receiver. Steam supplied to the low-
pressure cylinder first circulates through the jacket space,
entering at the bottom at a central opening. The jackets are
drained into tanks, which are emptied by means of pumps
operated by the engine. The water of condensation from this
source during the tests amounted to 600 Ibs. per hour, or
about 7 % of the total quantity of steam used by the engine.
The condenser is of the jet type with a direct connected air-
pump. Steam is supplied from horizontal return tubular boil-
ers. A calorimeter test showed that the amount of moisture
was T2o of 1 %. The exhaust valves and pistons of both
cylinders, and the steam valves of the low-pressure cylinder
were found to be practically tight. The steam valves of the
high-pressure cylinder showed some leakage. The load con-
sisted of cotton machinery.

OF THB

UNIVERSITY

ENGINE No. 34

H.P. Head End

I0n

5-
0-

5-
10-

L.P. Head End

10—

5-
0-

5-
10-

L.P. Crank End

ENGINE No. 35.

Compound Condensing Engine.

H. P.
CYLINDER.

L. P.

CYLINDER.

Kind of engine Single valve.

Number of cylinders .',..:. 1 1

Diameter of cylinder . . ... • ins. 13 22

Diameter of piston rod . ." . . . ins. lit 2S

Stroke of piston ins. 18

Clearance ... % 7 10

Horse-power constant for one Ib. in.e.p.

one revolution per minute . . . H.P. I .0119 .0344
Ratio of areas of cylinders .... 2.89

Inside diameter of steam pipe . . . ins. 4£

Inside diameter of exhaust pipe . . ins. 6.

Condition of valves and pistons regard- Considerable Considerable

ing leakage leakage leakage

Data and Results of Feed- Water Test.

Character of steam . . . . ... • ... • • ... . Ordinary

Duration ..../.... 5 hrs.

Weight of feed-water consumed . . 16,375 Ibs.

Feed-water consumed per hour . . 3,275 Ibs.

Pressure in steam pipe above atmosphere ........ 105.2 Ibs.

Vacuum in condenser . . ... . . . . .... . 28 ins.

Revolutions per minute ........ 197.1

Mean effective pressure H. P. cylinder 32.57 Ibs.

Mean effective pressure L. P. cylinder 10.63 Ibs.

Indicated horse-power H. P. cylinder .......'. 76.4 H.P.

Indicated horse-power L. P. cylinder . . *. , . . . . 72.1 H.P.

Indicated horse-power, whole engine . . . ^ . . . . 148.5 H.P.

Feed-water consumed per I. H. P. per hour ...;.. 22.05 Ibs.

Measurements based on Sample Diagrams.

H. P.
CYLINDER.

L. P.
CYLINDER.

Initial pressure above atmosphere .
Corresponding steam-pipe or receiver

pressure .........

Cut-off pressure above zero ... .

Release pressure above zero ....

Mean effective pressure . . . . -.. .

Back pressure at mid stroke above or

below atmosphere

Proportion of stroke completed at

cut-off

Steam accounted for at cut-off ... .
Steam accounted for at release . . .
Proportion of feed-water accounted for

at cut-off

Proportion of feed-water accounted for

at release

!43

Ibs.

Ibs.
Ibs.
Ibs.
Ibs.

104
84.6
43.6
33.21

Ibs. I +18

Ibs.
Ibs.

.382
13.73
14.95

.623
.678

11.5

16.9
11.

10.82

-9.5

.505
13.93
14.68

.632
.666

144 ENGINE TESTS.

Engine No. 35 is a horizontal cross-compound unjacketed
engine, provided with a shaft governor operating on the cut-off
of the high-pressure cylinder. The valves are of the piston
type without packing. A jet condenser is used operated by an
independent air-punip driven with steam taken from the engine
pipe. The quantity thus used, as also that consumed by the
boiler feed-pump, was determined by independent tests and
allowed for. Steam is supplied from vertical water- tube boil-
ers, and a separator placed in the steam pipe secured what was
believed to be commercially dry steam. The steam showed no
superheating. The valve in each cylinder was found to leak
badly. The piston of the high-pressure cylinder was fairly
tight. Owing to the leakage of the low-pressure valve no
leakage observations could be made upon the low-pressure
piston. The load consisted of dynamos furnishing current for
electric lighting.

There is a close agreement between the steam accounted for
by the indicator in the two cylinders, which might be surprising
in view of the fact that the cylinders are unjacketed, were it
not known that the steam valve of the high-pressure cylinder
showed considerable leakage. Some of the steam shown on
the low-pressure diagram was undoubtedly due to this cause.

ENGINE No. 35

IOO-,
80-
60-
40-
20-
0-

OF THE

UNIVERSITY

H.P. Head End

H. P. Crank End

r-IOO
80

— 60

— 40

— 20

— 0

L.P. Head End

- 10

- 5
— 0

- 5

- 10

10-,
5-
0-
5-

10-

L.P. Crank End

ENGINE No. 36.

Compound Condensing Engine.

H. P.

CYLINDER.

L. P.

CYLINDER.

Kind of engine
lumber of cylinders

ins.
ins.

ft.

%

H.P.

ins.
ins.

Four valve
1
16
3
4
2

.0479
1.00
6

Practice

(Corliss)
1
32
311
4
4

.1937
4.04

12
lly tight

Diameter of cylinder

Diameter of piston rod

Stroke of piston

Clearance .

H. P. constant for one Ib. m. e. p. one
revolution per minute ....
Ratio of areas of cylinders ....
Inside diameter of steam pipe . . .
Inside diameter of exhaust pipe ' . .
Condition of valves and pistons regard-
ing leakage

Data and Results of Feed -Water Test.

Character of steam

Duration

Weight of feed-water consumed

Feed-water consumed per hour

Pressure in steam pipe above atmosphere .
Pressure in receiver above atmosphere . .

Vacuum in condenser

Revolutions per minute

Mean effective pressure, H. P. cylinder . .
Mean effective pressure, L. P. cylinder . .
Indicated horse-power, H. P. cylinder . .
Indicated horse-power, L. P. cylinder . .
Indicated horse- power, whole engine . . .
Feed-water consumed per I. H. P. per hour .

Ordinary

5.05 hrs.

27,133 Ibs.

5,373 Ibs.

126.8 Ibs.

27.4
74.9
58.29
11.79
211.6
170.9
382.5
14.05

Ibs.

Ibs.
H.P.
H.P.
H.P.

Ibs.

Measurements based on Sample Diagrams.

H.P.

CYLINDER.

L. P.

CYLINDER.

Initial pressure above atmosphere . .
Cut-off pressure above zero ....
Release pressure above zero ....
Mean effective pressure

Ibs.
Ibs.
Ibs.
Ibs

116.5
120.7
39.4
59 4

7
18.4
7.4
11.97

Back pressure at mid stroke, above or
below atmosphere
Proportion of stroke completed at cut-off
Steam accounted for at cut-off . .
Steam accounted for at release . .
Proportion of feed-water accounted for
at cut-off .

Ibs.

Ibs.
Ibs.

+ 9.9
.295
10.78
12.

.767

-13.
.337
8.98
10.42

.64

Proportion of feed-water accounted for
at release

853

.741

146

ENGINE No. 36.^<^ 147

Engine No. 36 is a cross-compound horizontal engine with
steam jacketed cylinders and a jet condenser operated by a
direct connected air-pump. The jacket spaces in each cylinder
form a thoroughfare through which the steam is supplied to the
respective steam chests, the steam first entering the bottom of
the jacket at a central point. During the test the drain-pipes
provided for carrying off the water of condensation were closed,
and all this water passed over into the cylinder. Whatever
effect the jackets might otherwise have produced was thus
nullified, and the engine may be considered as practically un-
jacketed. Steam is supplied from vertical water tube-boilers,
and a separator is provided in the main steam pipe. For a
short period during the test, water accumulated in the sepa-
rator, and its quantity was determined and allowed for. For
the balance of the test there was no accumulation, and the
steam is presumed to be commercially dry. The valves and
pistons of both cylinders were practically tight. The load
consisted of dynamos supplying current for electric lighting.

Engine No. 36 belonged to the same plant as Nos. 30 and 35.

The behavior of the steam in its passage through the cylin-
ders which the analysis of the indicator diagrams reveals is of
unusual interest. The increase in the amount of steam shown
at release over cut-off is very large in both cylinders, and the
loss of steam which the low-pressure cylinder shows is a marked
feature. These actions may be attributed to the effect of the
jacket-water in the cylinders combined with the cooling action
which always takes place when steam parses from a high to a
low-pressure cylinder, where no means is provided for reducing
•cylinder condensation. In this case the quantities are unaf-
fected by steam which leaked, all the valves and pistons being
practically tight.

OF THK

UNIVERSITY

ENGINE No. 36

120-
100-
80-
60-
40-
20-
0-

H.P. Head End

H.P. Crank End

120
100
-80
-60
-40
-20
- 0

10-
5

o-

6-
10-

L.P. Head End

L.P. Crank End

- 10

- 5

- 0

- 5

ENGINE No. 37.

Compound Condensing Engine.

H.P.
CYLINDER.

L. P.

CYLINDER.

Kind of engine ....

Four valve

(Corliss)

Number of cylinders . ....

1

Diameter of cylinder ins.
Diameter of piston rod ins.

Stroke of piston ft.
Clearance %
H. P. constant for 1 Ib. m. e. p. one
revolution per minute .... H.P.

16*
2J

4£
2*

.0573

32
121
f«

4*
2*

.2162

Ratio of areas of cylinders ....
Condition of valves and pistons regard-
ing leakage

1
Fairly tight.

3.774

Data and Results of Feed- Water Test.

Character of steam

Duration

Weight of feed-water consumed

Feed-water consumed per hour

Pressure in steam pipe above atmosphere

Pressure in receiver above atmosphere

Vacuum in condenser

Revolutions per minute

Mean effective pressure, H. P. cylinder

Mean effective pressure, L. P. cylinder

Indicated horse-power, H. P. cylinder

Indicated horse-power, L. P. cylinder

Indicated horse-power, whole engine

Feed-water consumed per I. H. P. per hour

Ordinary

0.833

hrs.

3,122.

Ibs.

3,746

Ibs.

108

Ibs.

2

Ibs.

27

ins.

59

45.47

Ibs.

9.83

Ibs.

154.28

H.P.

125.85

H.P.

280.13

H.P.

13.37

Ibs.

Measurements based on Sample Diagrams.

H.P.

CYLINDER.

L. P.
CYLINDER.

Steam accounted for at cut-off . , . Ibs.
Steam accounted for at release . . . Ibs.
Proportion of feed-water accounted for
at cut-off

9.8

10.78

732

10.48
10.94

784

Proportion of feed-water accounted for
at release

806

818

Engine No. 37 is a tandem horizontal compound with cylin-
ders and heads steam jacketed. The condenser is of the jet
type, operated with an air-pump connected to the engine.

149

150 ENGINE TESTS.

Steam is supplied from vertical boilers, which gave steam that
was at times slightly superheated, and at other times in its ordi-
nary condition. The feed-water was measured on the test by
water-glass observations, the water being first pumped to a high
point, then shut off, and the test continued until the boilers
needed replenishing. The water drained from the jackets
amounted to 248 Ibs. per hour, or in round numbers, 7% of the
total quantity used by the engine. The load consisted mainly
of rubber grinding machinery.

The variable character of the load, and the short duration of
the test, make the results less accurate than they would be
if the load had been steady and the water had been measured
for a longer period. The sample indicator diagrams which are
here presented, owing to the fluctuating load, must be regarded
as showing the general distribution of the steam in the cylin-
ders rather than precise average samples of the work.

When the jackets were shut off, the distribution of the
steam was affected in a noticeable degree. The difference
between the steam shown at release and cut-off was greatly
increased.

ENGINE No. 37

H.P. Head End

[-100
-80
-60
-40
-20
- 0

H.P. Crank End

-100
-80
-60
-40
-20
- 0

5-

O-

5-

10-

L.P. Head End

5-
0-
5-
10-

L.P. Crank End

ENGINE No. 38.

Compound Condensing Engine.

-

H.P.
CYLINDER.

L. P.
CYLINDER.

Kind of engine
Number of cylinders
Diameter of cylinder ins.
Diameter of piston rod ins.
Stroke of piston . . ft.

Four valve
1
22
3.5
5
2.5

.0114
1

Practically
tight

(Corliss)
1
44
3.5
5
2.5

.0459
4.03

Excessive
leakage

Clearance %
H. P. Constant for one Ib. m.e.p., one
rev. per minute H.P.
Ratio of areas of cylinders ....
Condition of valves and pistons regard-
ing leakage .

Data and Results of Feed -Water Test.
Character of steam - Ord

inary
hrs.
Ibs.
Ibs.
Ibs.
Ibs.
ins.

Ibs.
Ibs.
H.P.
H.P.
H.P.
Ibs.

Duration .

. . 8.58

Weight of feed- water consumed
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
Pressure in receiver

. . 118,927
. . 13,861
. . 108.9
. . 8.4

Vacuum in condenser .

. . 23.6
. . 62.14
. . 61.53

. . 9.87

Revolutions per minute
Mean effective pressure, H. P. cylinder
Mean effective pressure L P cylinder

Indicated horse-power H P cylinder

. . 434.6

Indicated horse-power, L. P. cylinder
Indicated horse-power, whole engine
~Ffip.rUwat,p.r Consumed ner I. H. P. Der hour .

. . 281.4
. . 716
19.36

Measurements Based on Sample Diagrams.

H.P.
CYLINDER.

L. P.
CYLINDER.

Initial pressure above atmosphere . .
Cut-off pressure above zero ....
Release pressure above zero ....
Mean effective pressure

Ibs.
Ibs.
Ibs.
Ibs.

112
111
45.7

62.08

8
1-6.8
6.2
9.84

Back pressure at mid stroke above or
below atmosphere

Ibs.

+ 10

— 11

Proportion of stroke completed at
cut-off
Steam accounted for at cut-off . . .
Steam accounted for at release . . .
Proportion of feed-water accounted for

Ibs.
Ibs.

.377
13.07
12.76

.675

.381
8.42
8.67

.435

Proportion of feed-water accounted for
at release

.^____ _____ __^__ — — — — — — ^— — — —

.659

.448

152

ENGINE No. 38. 153

Engine No. 38 is a horizontal cross compound. The cylin-
ders are steam-jacketed, and the intermediate receiver, which is
a chamber 30" in diameter and 8" high, is also jacketed. The
arrangement of the jacket^piping is such that the drain pipe of
the high-pressure jacket supplies the low-pressure jacket, and
the drain pipe of this supplies the receiver jacket, and their
sizes are so proportioned that there is a continual reduction of
pressure from one point to the next, and consequently a con-
tinuous circulation. The engine is fitted with a jet condenser
operated by a direct connected air-pump. Steam is furnished
by horizontal return tubular boilers located at a distance of
some 200 feet. The water of condensation which collects in
the steam pipe is carried back to a feed tank in the boiler-room,
and steam used by the feed pump exhausts into the same tank.
There was some leakage of joints in the steam piping which
has not been allowed for. The valves and pistons of the high-
pressure cylinder were practically tight. The valves of the
low-pressure cylinder were tight, but the piston contained a
loosely fitting packing ring and leaked very badly. The load
consisted of cordage machinery.

The interest in this test centers upon the effect which was
produced by excessive leakage through the low-pressure piston.
In a well jacketed engine the steam accounted for by the indi-
cator is nearly as great in the low-pressure cylinder as in the
high pressure cylinder. In this case there is a reduction from
.675 to .435, or 24% of the total weight of steam consumed,
and this is evidently due to the leakage referred to.

ENGINE No. 38

120^

100-

80-

60-

40-

20-

0-

H.P. Head End

H.P. Crank End

-120
-100
- 80
— 60
—40
—20
0

L.P. Head End

10

- 5

- 0

- 5

- 10

10

5 -
0-

6 -
10 —

L.P. Crank End

ENGINE No. 39.

Compound Condensing Engine.

H. P.
CYLINDER.

L. P.

CYLINDER.

Kind of engine . •

Single

valve

Number of cylinders

1

Diameter of cylinder ins.

13

26

Diameter of piston rod ins

lit

2*

Stroke of piston ins

18

18

Clearance %

7

10

Horse-power constant for one Ib. m.e.p.

one revolution per minute . . . H.P.

.0019

.048

Ratio of areas of cylinders ....

1

4.03

Condition of valves and pistons regard-

Considerable

Considerable

ing leakage

leakage

leakage

Data and Results of Feed -Water Test.

Character of steam

Duration

Weight of feed-water consumed 11

Feed-water consumed per hour 3

Pressure in steam pipe above atmosphere

Vacuum in condenser

Revolutions per minute

Mean effective pressure H. P. cylinder

Mean effective pressure L. P. cylinder

Indicated horse-power H. P. cylinder

Indicated horse-power L. P. cylinder

Indicated horse-power, whole engine

Feed-water consumed per I. H. P. per hour

Measurements based on Sample Diagrams.

Ordinary

2.85

hrs.

,325

Ibs.

,973.7

Ibs.

120.6

Ibs.

27

ins.

195.3

43.75

Ibs.

12.68

Ibs.

101.7

H.P.

118.9

H.P.

220.6

H.P.

18.01

Ibs.

H. P.
CYLINDER.

L. P.
CYLINDER.

Initial pressure above atmosphere .
Cut-off pressure above zero ....
Release pressure above zero ....
Mean effective pressure

Ibs.
Ibs.
Ibs.
Ibs

115.5
104.9
55.4
43 1

15
20.6
10.3
12 69

Back pressure at mid stroke, above or
below atmosphere

Ibs

+ 23

— 10 5

Proportion of stroke completed at cut-off
Steam accounted for at cut-off .
Steam accounted for at release .
Proportion of feed-water accounted for
at cut-off

Ibs.
Ibs.

.396
11.33
12.3

629

.387
12.49
12.49

694

Proportion of feed-water accounted for
at release ... ....

683

694

155

156 ENGINE TESTS.

Engine No. 39 is a single valve, cross compound, unjacketed
engine, with a shaft governor operating 011 the cut-off of the
high-pressure cylinder. The valves are of the piston type pro-
vided with an inefficient ring packing. A jet condenser is
used, operated by an independent air-pump driven with steam
taken from the engine pipe. The quantity thus used was
determined by an independent test and allowed for. Steam is
supplied from vertical water- tube boilers, and a separator placed
in the steam pipe secured what was believed to be commercially
dry steam without superheating. The valves and pistons all
leaked a considerable amount. The load consisted of dynamos
furnishing current for electric lighting. With the exception
of the low-pressure cylinder and the valves, this engine is
the same as No. 35. During the interval between the tests the
engine had been provided with new valves fitted with packing
and a complete new low-pressure cylinder of larger size.

Referring to the test on Engine No. 35, the figures given here
show an improvement, due largely to a better distribution of
the steam, which was accomplished by a change of proportion
in the steam cylinders. The increase in the size of the low-
pressure cylinder enabled this cylinder to do a larger proportion
of the work, with corresponding advantage. The reduction
in the quantity of feed water consumed per horse power per
hour amounted to 18.3% ; and the reduction in the steam
accounted for by the diagrams at cut-off, which is 17.5%, fur-
nishes a reason for the change. In view of the leakage of the
valves and pistons, it is not surprising that the proportion of
steam accounted for is low ; and this is true in the case of both
engines.

To make a ready comparison of the diagrams in the two
cases under consideration, showing the general effect of the
change of cylinders, diagrams t'rom Engine No. 35, taken with
the same load, are superposed in dotted lines upon those relat-
ing to No. 39, which are represented in full lines.

120-n

100-
80-
60-
40-
20-

0-
120-

100-

80-
60-
40-
20-
0-

ENGINENo. 39

H.P. Head End

H.P. Crank End

20-

10-

o-

10-

L.P. Head End

L.P. Crank End

-20

- 10

- 0

- 10

ENGINE No. 40.

Compound Condensing Engine.

H. P.
CYLINDER.

L. P.
CYLINDER

Kind of engine

Single

valve

Number of cylinders

1

1

Diameter of cylinders . ins.

18

30

Stroke of piston ins.

16

1(3

Clearance %

33

9

H. P. constant for 1 Ib. in. e. p. one rev-

olution per inin H.P.

.0103

.0285

Katio of areas of cylinders

1

2.78

Condition of valves and pistons regarding

Practically

Practically

leakage

tight

tight

Data and Results of Feed -Water Test.

Character of steam

Duration

Weight of feed -water consumed

Feed-water consumed per hour

Pressure in steam pipe above atmosphere

Vacuum in condenser

Revolutions per minute

Mean effective pressure, H. P. cylinder

Mean effective pressure, L. P. cylinder

Indicated horse-power, H. P. cylinder

Indicated horse-power, L. P. cylinder

Indicated horse-power, whole engine

Feed-water consumed per I. H. P. per hour

Ordinary

1.527

hrs.

9,660

Ibs.

6,326.1

Ibs.

126

Ibs.

21.1

ins.

228

63.9

Ibs.

30.4

Ibs.

149.7

H.P.

197.9

H.P.

347.6

H.P.

18.2

Ibs.

Measurements based on Sample Diagrams.

H.P.
CYLINDER.

L. P.
CYLINDER.

Initial pressure above atmosphere . . Ibs.

111.6

49

Cut-off pressure above zero .... Ibs.

114.8

29.7

Release pressure above zero .... Ibs.

82.4

25.7

Mean effective pressure Ibs.

63.4

30.1

Back pressure at mid stroke, above or

below atmosphere Ibs.

+ 24.5

( .

Proportion of stroke completed at cut-off

.595

.795

Steam accounted for at cut-off . . . Ibs.

16.58

17.58

Steam accounted for at release . . . Ibs.

15.59

16.11

Proportion of feed-water accounted for

at cut-off

.911

.965

Proportion of feed-water accounted for

at release

.857

.885

158

159

Engine No. 40 is a vertical single-acting engine with unjack-
eted cylinders and a single piston valve fitted with ring pack-
ing, one valve serving for both cylinders. The condensing
apparatus is a surface condenser with air-pump operated by
steam. During the test the exhaust from the air-pump escaped
to the atmosphere. This pump was of insufficient size to give
a proper vacuum. Steam is furnished by horizontal return
tubular boilers. It was found by calorimeter test that at a
point near the engine it contained one-half of \°/0 of moisture.
The pistons and the valve were practically tight, although in
this class of engines there is always some escape of water by
the piston rings into the crank case. The load consisted of a
centrifugal pump.

The feed- water was measured by collecting the water dis-
charged from the surface condenser. The quantity thus deter-
mined does not include that referred to above, which leaked
from the steam cylinders into the crank case, and which there is
no ready means of determining.

The consumption of feed-water here given was less than the
actual amount of steam which passed through the engine,
owing to the fact above noted that some of the steam which
was condensed in the cylinders passed into the crank case and
failed to be measured. This accounts for the large proportions
which the steam accounted for at cut-off and release bears to
the feed-water consumption. In view of the late cut-off, the
high back pressure in the small cylinder, the excellent quality
of the steam furnished to the engine, and the tightness of the
valve, all of which tend to reduce the losses shown by an
analysis of the diagram, these proportions must necessarily be
large. The leakage referred to could hardly be expected to
exceed 5%. Assuming it to be 5%, the feed- water consump-
tion would stand 19.1 Ibs., and the proportions of steam ac-
counted for at cut-off in the two cylinders .87 and .92 respect-
ively.

ENGINE No. 40

H.P. Cyl.

-100
-80

• 60
40
20

- 0

L.P. Cyl.

- 40

- 20

ENGINE No. 41.

Compound Condensing Engine.

H. P.
CYLINDER.

L. P.

CYLINDER.

Kind of engine
Number of cylinders
Diameter of cylinder

ins.
ins.
ins.

%

H.P.

ins.
ins.

Single
1

in

2
13

7

.00672
1
4
5
Considerable
leakage

valve
1
18i
2
13
10

.01755
2.61
5

7

Diameter of piston rod . . . .
Stroke of piston
Clearance

H. P. constant for one Ib. m. e. p. one
revolution per minute . . . .
Ratio of areas of cylinders ....
Inside diameter of steam pipe
Inside diameter of exhaust pipe
Condition of valves and pistons regard-
ing leakage

Data and Results of Feed -Water Tests.

TEST.
CHARACTER OF LOAD.

A.
LIGHT LOAD.

B.
HEAVY LOAD.

Character of steam
Duration hrs.
Weight of feed-water consumed. . . Ibs.
Eeed-water consumed per hour . . . Ibs.
Pressure in steam pipe above atmos. Ibs.
Vacuum in condenser ins

Ordinary
3.5
7,203.5

2,058
129.7
25 9

Ordinary
4.8
18,043.
3,759
130.1
25 5

Revolutions per minute

306

298 5

Mean effective pressure, H. P. cylinder Ibs.
Mean effective pressure, L. P. cylinder Ibs.
Indicated horse-power, H. P. cylinder H.P.
Indicated horse-power, L. P. cylinder H.P.
Indicated horse-power, whole engine . H.P.
Feed-water consumed per I. H.P. per hr. Ibs.

25.02
7.27
51.5
39.
90.5
22.74

48.5
19
97.3
99.5
196.8
19.1

Measurements based on Sample Diagrams, heavy load Test.

TEST.

H.P.
CYLINDER.

L. P.
CYLINDER.

Initial pressure above atmosphere . . Ibs.
Corresponding steam-pipe or receiver
pressure Ibs.
Cut-off pressure above zero .... Ibs.
Release pressure above zero .... Ibs.
Mean effective pressure . Ibs

130

132
115.2
63.1

48 9

20.3

24.6 '
15.

19 2

Back pressure at mid stroke above or
below atmosphere Ibs.
Proportion of stroke completed at cut-off
Steam accounted for at cut-off . . . Ibs.
Steam accounted for at release . . . Ibs.
Proportion of feed-water accounted for
at cut-off

+ 20.3
.382
12.03
13.43

629

— 11.1
.409
9.97
12.76

522

Proportion of feed-w. acc'd for at release

.703

.668

161

162 ENGINE TESTS.

Engine No. 41 is a vertical cross-compound unjacketed high-
speed engine, having unpacked piston valves, one for each
cylinder, and controlled by a shaft governor operating on the
cut-off of the high-pressure cylinder. A jet condenser is used,
operated by an independent air-pump driven by steam taken
from the main pipe. The quantity of steam used by the con-
denser was determined by an independent test and allowed for.
Allowance was also made for steam condensed in the large ser-
vice main, which was designed for supplying several other
engines besides the one tested. Steam was furnished by hori-
zontal return tubular boilers, and a calorimeter test showed that
it contained T% of 1% of moisture. The valve of the high-
pressure cylinder was found to leak quite badly. That of the
low-pressure cylinder was reasonably tight. The leakage of
the valves interfered with a determination of the condition of
the pistons. The load consisted of dynamos furnishing cur-
rent for electric lighting. The tests were made with two differ-
ent loads, other conditions remaining the same.

If the results of this test are compared with those made on
a four- valve engine such as No. 36, which showed a much more
economical performance, the effect of various features in the
design of the engine are apparent. Engine No. 41 had a single
valve, which secured less perfect distribution of steam than the
four valves of the other engine. It had larger percentages of
clearance space, and finally, the type of valve used permitted a
much larger amount of leakage than occurred in the other
engine. Engine No. 41, however, had the advantage of more
rapid reciprocations ; but this, it appears, did not have sufficient
effect to overcome the losses due to the causes mentioned.

ENGINE No. 41a

I20-,
100-
80-
60-
40-
20-

o-

100-
80-
60-
40-
20-

o-

H.P. Top

L.P. Top

L.P. Bottom

ENGINE No.41b

120^

100-

80-

60-

40-

20-

0-

120 —

100-

80—

60-

40

20-

0-

H.P. Top

H-P. Bottom

20-
10-
0—
10-

20-
10-

O-
10-

L.P.Top

L.P. Bottom

ENGINE No. 42.

Compound Non-Condensing Engine.

H.P.

CYLINDER.

L.P.

CYLINDER.

Kind of engine

Single valve

Number of cylinders . . . .

I

1

Diameter of cylinders .... ins.

1H

182

Diameter of piston rod . . . . ins.

2

2

Stroke of piston ins.

13

13

Clearance . %

7

10

H. P. Constant for one Ib. m. e. p.

one rev. per min H.P.

.00672

.01755

Ratio of areas of cylinders ....

1

2.61

Condition of valves and pistons

Considerable

regarding leakage ....

leakage

Data and Results of Feed - Water Tests.

TEST.
CONDITIONS REGARDING LOAD.

A.

LIGHT LOAD.

B.
HEAVY LOAD.

Character of steam ... ^ . . .

Ordinary

Ordinary

Duration . . . . ... . hrs.

5

5

Weight of feed-water consumed . Ibs.

10,228

15,369

Feed-water consumed per hour . Ibs.

2,045.6

3,842.2

Press, in steam pipe above atmos. Ibs.

126.5

128

Revolutions per minute ....

300.2

292.7

Mean effective pressure, H.P. cyl. Ibs.

20.36

42.16

Mean effective pressure, L.P. cyl. Ibs.

.86

13.56

Indicated horse-power, H. P. cyl. H.P.

41.05

82.89

Indicated horse-power, L. P. cyl. H.P.

4.53

69.59

Indicated H. P., whole engine . H.P.

45.58

152.48

Feed-water cons, per I. H.P. per hr. Ibs.

44.89

25.2

Measurements based on Sample Diagrams.

TEST.
CONDITIONS REGARDING LOAD.

H.P. CYL.

L.P. CYL.

H.P.CYL.

L.P. CYL.

Initial pressure above atmosphere Ibs.

116.4

10.3

120

30

Corresponding steam-pipe or re-

ceiver pressure Ibs.

125.

128.

Cut-off pressure above zero . . Ibs.

112.4

19.5

120.3

53.5

Release pressure above zero . . Ibs.

40 9

64.7

20.6

Mean effective pressure . . . Ibs.

20.2

.7

42.27

14.1

Backpressure atniid stroke above

atmosphere Ibs.

10.7

1.

29.9

1.8

Proportion of stroke completed

at cut-off

.107

.526

.389

.424

Steam accounted for at cut-off . Ibs.

10.21

28.26

15.56

13.82

Steam accounted for at release . Ibs.

26.43

17.16

16.66

Proportion of feed-water account-

ed for at cut-off ....

.228

.629

.617

.548

Proportion of feed-water account-

ed for at release . . . v

.589

.681

.661

165

166 ENGINE TESTS.

Engine No. 42 is of the vertical cross-compound un jacketed
high-speed class. It is a duplicate of Engine No. 41, being
located in the same power house, and forming a part of the
same plant. It was supplied with steam from a different por-
tion of the service main, the water condensed in which returned
back to the boiler. Unlike engine No. 41 it was run non-con-
densing. The valves and pistons leaked to about the same
extent as in the other engine, and the load was of the same
character. The tests were two in number, one being made
with a very light load.

These tests bring out very forcibly the wastefulness of a non-
condensing compound engine of this type when carrying an
extremely light load. In the case of the first test the load was
so small that the low-pressure cylinder contributed only about
10% of the whole power, which is so small as to be immaterial ;
and consequently, the engine showed simply the economy due
to a non-condensing cylinder of this type carrying a high back
pressure, and working at a comparatively early cut-off. The
effect of valve leakage is revealed by the small proportion of
steam accounted for by the indicator. Compared with the con-
densing engine of the same type, No. 41, there is a marked
advantage due to the use of the condenser ; and this appears to
be especially true in the case of the light load. Comparing the
two heavy-load tests the reduced consumption of feed-water is
6.1 Ibs. per I. H. P. per hour, or about 24%. In the light-load
test there is a remarkable increase in the steam accounted for
at release of the high-pressure cylinder over that shown at cut-
off. It is due largely no doubt to valve leakage.

ENGINE No. 42a

H.P. Top

H.P. Bottom

120
-100
-80

— 60
-40
-20

- 0
120

-100

- 80

— 60
40

-20

- 0

L.P. Top

-30
-20

— 10

— 0

L.P. Bottom

—20
- 10

0

ENGINE No.42b

H.P. Top

H.P. Bottom

-120
-100
-80

- 60
-40
-20

- 0
-120
-100
-80
-60
-40
-20

- 0

L.P. Top

L.P. Bottom

30

20

10

0

ENGINE No. 43.

Compound Condensing Engine.

H.P. CYLINDER.

L.P. CYLINDER.

Kind of engine
Number of cylinders

Four valve
1

27.9
5
5
2.5

.1828
1
12

Fairly tight

(Corliss)
1
48.3
6
5
2.5

.556
3.04

Fairly tight

Diameter of cylinder . . ins.

Diameter of piston rod ins.
Stroke of piston ft.

Clearance (assumed) %
H. P. constant for one Ib. m. e. p. one
rev. per min H.P.
Ratio of areas of cylinders . . . .
Inside diameter of steam pipe . . . ins.
Condition of valves and pistons regard-
in0" leakage

Data and Results of Feed - Water Test.

Character of steam Superh'd 44.

Duration V •, • 19-08

Weight of feed-water consumed 257,351

Feed-water consumed per hour 13,488

Pressure in steam pipe above atmosphere
Pressure in receiver above atmosphere .

Vacuum in condenser .

Revolutions per minute

Mean effective pressure H. P. cylinder . .
Mean effective pressure L. P. cylinder . .
Indicated horse-power H. P. cylinder . .
Indicated horse-power L. P. cylinder . .
Indicated horse-power, whole engine . .
Feed-water consumed per I. H. P. per hour

119.8
11.0
25.7
70.03
39.04
13.28
499.9
517.2
1,017.1
13.26

5 degs.
hrs.
Ibs.
Ibs.
Ibs.
Ibs.
ins.

Ibs..
H.P.
H.P.
H.P.
Ibs.

Measurements Based on Sample Diagrams.

H. P.

CYLINDER.

L.P.
CYLINDER.

Initial pressure above atmosphere . . .

Ibs.

109

12.9

Corresponding steam-pipe or receiver press.

Ibs.

113

Cut-off pressure above zero

Ibs.

114.8

22.1

Release pressure above zero

Ibs.

31.4

7.4

Mean effective pressure .

Ibs.

40.03

13.21

Back pressure at mid stroke, above or be-

low atmosphere

Ibs.

+ 16.

-12.2

Proportion of stroke completed at cut-off .

.236

.312

Steam accounted for at cut-off ....

Ibs.

10.1

9.39

Steam accounted for at release ....

Ibs.

12.0

10.21

Proportion of feed-water accounted for at

cut-off

.762

.708

Proportion of feed-water accounted for at

release

.908

.77

169

170 ENGINE TESTS.

Engine No. 43 is a horizontal cross compound with jacketed
cylinders and unjacketed receiver. It exhausts into a jet con-
denser provided with a direct connected air-pump. The jacket
space of either cylinder, which is confined to the barrel of the
cylinder, forms a thoroughfare through which the steam passes
to the top chest, the steam entering at the bottom. The spaces
are drained by traps. Steam is supplied by vertical boilers
which superheat. The valves and pistons of the H. P. cylin-
der leaked a small amount, but those of the L. P. cylinder were
practically tight. The load consisted of cotton machinery.

The test reported is the collective result of four indepen-
dent trials of 4.5 to 5 hours each.

A noticeable feature in these results is the increase in the
steam accounted for at release H. P. cylinder over that shown
at cut-off, viz., .146. In working out these figures the clear-
ance was assumed at 2-J- %. If the clearance were in reality
1 % more (i. e., 3.5 %) the increase is reduced to .123. Even
this is notable.

ENGINE No. 43

H.P. Head End

100
80
60
40
20
0

H.P. Crank End

100
80
60
40
20
- 0

L.P. Head End

L.P. Crank End

15
10
5
0
6
10

15
10

6'
0

L- 10

ENGINE No. 44.

Compound Non-Condensing Engine.

H.P.

CYLINDER.

L. P.

CYLINDER.

Kind of engine
Number of cylinders

Single
1

valve
1

Diameter of cylinder . ... . . ins.
Stroke of piston ft.
Clearance %

11
11
33

19
11
9

H. P. constant for 1 Ib. m. e. p. one
revolution per minute .... H.P.
Ratio of areas of cylinders ....
Inside diameter of steam pipe . . . ins.
Condition of valves and pistons regard-
in0" leakage ....

.00264
1
5

Practically
ti°'ht

.00788
2.98

Practically
tio-ht

Data and Results of Feed- Water Test.

Character of steam . . . . . . . . .

Duration ....•-..

Weight of feed-water consumed . . . . .
Feed-water consumed per hour .....
Pressure in steam pipe above atmosphere . .

Revolutions per minute

Mean effective pressure, H. P. cylinder . .
Mean effective pressure, L. P. cylinder . .
Indicated horse-power, H. P. cylinder . .
Indicated horse-power, L. P. cylinder . . ,
Indicated horse- power, whole engine . . .
Feed-water consumed per I. H. P. per hour .

Ordinary

5.33

hrs.

13,397

Ibs.

2,511.8

Ibs.

135.9

Ibs.

296.3

67.2

Ibs.

23.3

Ibs.

53.6

H.P.

56

H.P.

109.66

H.P.

22.91

Ibs.

Measurements based on Sample Diagrams.

H.P.
CYLINDER.

L. P.
CYLINDER.

Initial pressure above atmosphere . ,
Corresponding steam-pipe pressure
Cut-off pressure above zero . . .1
Release pressure above zero . . '.' .
Mean effective pressure • .

Ibs.
Ibs.
Ibs.
Ibs.
Ibs.

130
132
128.2
89.5
67.1

55

35.5

28.4
23 6

Back pressure at lowest point above
atmosphere
Proportion of stroke completed at cut-
off

Ibs.

30
.605

0
.662

Steam accounted for at cut-off . . .
Steam accounted for at release . . .
Proportion of feed- water accounted for
at cut-off

Ibs.
Ibs.

18.39
18.56

.803

14.96
16.61

.653

Proportion of feed-water accounted for
at release

.81

.725

172

ENGINE No. 44.

173

Engine No. 44 is a vertical cross-compound, single-acting,
un jacketed, high-speed engine, having a single piston valve
fitted with ring packing, the speed being controlled by a shaft
governor. Steam is supplied by a horizontal return tubular
boiler, which by calorimeter test contained some 2% of moist-
ture. Drip pockets in the main pipe and at the throttle valve,
which were trapped, intercepted most of the entrained water
which would otherwise have passed into the engine. The load
consisted of an electric generator with constant output. The
valve and pistons were very nearly tight.

120-
100-
80
60-
40-
20-
0-

L.P. Cyl.

-60

-40

-20

- 0

ENGINE No. 45.

Compound Condensing Engine.

H. P. CYMNDEB.

L. P. CYLIXDER.

Kind of engine

Doubl
1
14
21
24
3.6

.01839
1

Consider a"

3 valve
1
28
21
24
6.4

.07436
4.04

Die leakage

Number of cylinders . . . . .
Diameter of cylinder ins.

Diameter of piston rod ins

Stroke of piston . ,~ ins.
Clearance ' . %
H.P. constant for one Ib. m.e.p. one
revolution per minute . . . .H.P.
Ratio of areas of cylinders ....
Condition of valves and pistons regard-
ing leakage

Data and Results of Feed - Water Tests.

TEST.

A.

B.

C.

Character of steam '.
Duration hrs

Ordinary
4

Ordinary
4

Ordinary
3

Weight of feed-water consumed . . Ibs.
Feed-water consumed per hour . . . Ibs.
Pressure in steam -pipe above atmos. . Ibs.
Pressure in receiver Ibs

19,014
4,753.7
119.9
10 1

15,366
3,841.6
120.4
4 5

6,375
2,125
117.6

Vacuum in condenser ins

25 1

25 5

25 6

Revolutions per minute

161 75

162 75

170 1

Mean effective pressure, H. P. cylinder Ibs.
Mean effective pressure, L. P. cylinder Ibs.
Indicated horse-power, H. P. cylinder H.P.
Indicated horse-power, L. P. cylinder H.P.
Indicated horse-power, whole engine . H.P.
Feed-water consumed per I. H. P. per
hour "".... Ibs.

57.4
10.39
170.74
124.97

295.71

16.07

49.97
7.85
149.55
95
244.55

15.71

25.89
8.35
80.98
42.41
123.39

17.22

Measurements based on Sample Diagrams.

TEST.

A

.

C

Initial pressure above atmosphere . . Ibs.
Corresponding steam-pipe or receiver
pressure Ibs

H.P.
117.4

120

L.P.
9.5

10 5

H.P.

118

119

L.P.

5.1

Cut-off pressure above zero .... Ibs.
Release pressure above zero .... Ibs.
Mean effective pressure Ibs.
Back pressure at mid stroke above or
below atmospere . . Ibs

114.5
42.5
57.95

+10 9

18.6

7.7
10.37

—11 6

121.8
14.1
24.97

— 36

7.5
3.7
3.47

—12 4

Proportion of stroke completed at cut-
off

.336

.338

044

336

Steam accounted for at cut-off . . . Ibs.
Steam accounted for at release . . . Ibs.
Proportion of feed-water accounted for
at cut-off

12.08
12.75

751

9.06
10.69

563

6.21
11.32

361

8.67
12.82

503

Proportion of feed-water accounted for
at release

.793

.665

.657

.744

174

ENGINE No. 45.

175

ENGINE No. 45 (Continued),
Data and Results of Feed-Water Tests.

TEST.

D.

E. .
NON-
CONDENSING.

Character of steam

Ordinary
3
13,356.5
4,45^.2
118.9
14.1
25.8
164.77
46.94
10.99
142.23
134.65
276.88
16.07

Ordinary
3
18,614
6,204.7
118
27.8

165.66
52.4
8.81
158.54
108.47
267.1
23.24

Duration . hrs.

Weight of feed-water consumed . . Ibs.
Feed-water consumed per hour . . . Ibs.
Pressure in steam pipe above atmos. Ibs.
Pressure in receiver above atmosphere Ibs.
Vacuum in condenser . ins

Revolutions per minute

Mean effective pressure, H. P. cylinder Ibs.
Mean effective pressure, L. P. cylinder Ibs.
Indicated horse-power, H. P. cylinder H.P.
Indicated horse-power, L. P. cylinder H.P.
Indicated horse-power, whole engine . H.P.
Feed-water consumed per I. H.P. per hr. Ibs.

Measurements based on Sample Diagrams.

TEST.

D.
CONDENSING.

E.

NON-
CONDENSING.

Initial pressure above atmosphere . . Ibs.
Corresponding steam-pipe or receiver
pressure
Cut-off pressure above zero .... Ibs.
Release pressure above zero .... Ibs.
Mean effective pressure Ibs.
Back pressure at mid stroke above or
below atmosphere . . . Ibs.

H.P.CY.

117.6

118
113.1
38.3
47.65

+16.

.3
11.16
12.06

.694

.750

L.P. CY.
14.1

14.5
22.2
7.0
11.07

-12.2

.239
8.82
10.71

.548
.666

H.P.CY.
113.1

115
110.8
58.2
50.94

+28.7

.487
18.46
19.1

.794

.821

L.P. CY.

27.8

28.5
31.9
14.9

8.77

+1.2

.406
15.83
18.3

.681

.787

Proportion of stroke completed at cut-
off

Steam accounted for at cut-off . . . Ibs.
Steam accounted for at release . . . Ibs.
Proportion of feed-water accounted for
at cut-off
Proportion of feed-water accounted for
at release

Engine No. 45 is a horizontal cross-compound with unjack-
eted cylinders and unjacketed receiver. There is a shaft gov-
ernor operating on the cut-off of the H. P. cylinder. The
main valves are balanced slides. The cut-off valve rides on a
seat in the interior of the main valve, which is of box pattern.
The engine exhausts into a surface condenser, with indepen-
dent air-pumps, the latter exhausting to waste. The feed-water

176 ENGINE TESTS.

consumption was found by weighing the water discharged by
the air-pump. Steam was drawn from the main service of a
large plant, and a calorimeter test showed that it was practically
dry. The main valve of the H. P. cylinder leaked quite badly.
The other valves and pistons leaked a small amount. The
engine supplied power to dynamos for electric lighting. A
series of tests was made with different loads, and in one case
the engine was run non-condensing.

Considering the wide changes of load in the tests A, B, and
C, viz., from 295. H. P. to 123. H. P., the small difference in
economy, 15.71 to 17.22, is noteworthy. Probably the leakage
of the valves of the H. P. cylinder affected the matter, but to
what extent can only be conjectured. The economy is at best
much below that obtained from some of the four- valve engines,
and excessive leakage is the only thing which satisfactorily
explains it. The results of tests D and E, condensing and
non-condensing, are respectively 16.07 Ibs. and 23.24 Ibs., from
which it appears that the consumption when running condens-
ing was 30.9% less than when running non-condensing.

ENGINE No. 45a

H. P. Head End

H.P. Crank End

120

100

80

60

40

20

0

120
100
80
60
40
20
0

L.P. Head End

L.P. Crank End

ENGINE No. 45c

H.P. Head End

H.P. Crank End

-120
-100

- 80

- 60
-40
-20

— 0
-120

100
-80
. 60

- 40

- 20

- 0

L.P. Head End

L.P. Crank End

o

5
10
15

ENGINE No. 45d

H.P. Head End

H. P. Crank End

120
-IOO
-8O
-6O
-40
-20

- 0
-120

-100
-80
-60
-4O
-20
- O

L P. Head End

15
10
5
O

5

10

15
IO
5
O
5
10

ENGINE No.4-5e

H.P. Head End

H.P. Crank End

-120
-100
-80
-60
-4O

-20
- 0
-120
-100
-80
-60
-40

-20
L- 0

L.P. Head End

-30

-20

- 10

- 0

ENGINE No. 46.

Compound Non-Condensing Engine.

H.P.
CYLINDER.

L. P.
CYLINDER.

Kind of engine . . . ...

Four valve

Number of cylinders

I

1 i

Diameter of cylinders . ... .

ins.

17.5

28

Diameter of piston rod . . . .'.

ins.

31

31

Stroke of piston . .,..='; . •

ins.

48

48

Clearance

%

4.1

5.8

H. P. Constant for one Ib. in. e. p.

one rev. per min

H.P

.0572

.148

Ratio of areas of cylinders .

1

2.587

Inside diameter of steam pipe .

ins.

7

Inside diameter of exhaust pipe .

ins.

8

12

Condition of valves and pistons

regarding leakage ....

Practically tight

Data and Results of Feed -Water Tests.

TEST.

A.

B.

Character of steam . . .

Ordinary

Ordinary

Duration . . , . , . . . . hrs.

8.55

7.87

Weight of feed-water consumed . Ibs.

65,591

82,697

Feed-water consumed per hour . Ibs.

7,671.2

10,507.9

Press, in steam pipe above atmos. Ibs.

128.7

135.5

Pressure in receiver above atmos.

27.2

29.5

Revolutions per minute ....

101.02

99.06

Mean effective pressure, H.P. cyl. Ibs.

34.83

52.42

Mean effective pressure, L.P. cyl. Ibs.

9.75

14.19

Indicated horse-power, H. P. cyl. H.P.

201.3

278.84

Indicated horse-power, L. P. cyl. H.P.

145.6

207.85

Indicated H. P., whole engine . H.P.

346.9

486 69

Feed-water cons, per I. H. P. per hr. Ibs.

22.11

21.59

Measurements based on Sample Diagrams.

H.P.CYL.

L.P. CYL.

H.'P.CYL.

L.P. CYL.

Initial pressure above atmosphere Ibs.
Corresponding steam-pipe pres-
sure Ibs

118.8

129 2

28.01

125.3
136

30.3

Cut-off pressure above zero . . Ibs.
Release pressure above zero . . Ibs.
Mean effective pressure . . . Ibs.
Back pressure at mid stroke above
atmosphere Ibs

112.37
3981
34.66

32 0

34.31

13.88
9.66

2 2

116.52
51.76
49.03

34 3

34.91
18.26
14.22

2 9

Proportion of stroke completed
at cut-off

309

338

419

474

Steam accounted for at cut-off . Ibs.
Steam accounted for at release . Ibs.
Proportion of feed-water account-
ed for at cut-off ....
Proportion of feed-water account-
ed for at release ....

17.83
20.34

.806
.919

15.81
18.61

.715
.842

17.62
18.43

.816
.854

16.03
17.54

.743
.813

181

182 ENGINE TESTS.

Engine No. 46 is a cross-compound, with horizontal unjack-
eted cylinders and unjacketed receiver. The valves are all
plain slides. The steam was drawn from horizontal water-tube
boilers, and contained 0.7 % of moisture by calorimeter test.
The load was miscellaneous iron-working machinery. Tests
were made with two different loads. The valves and pistons
were all in excellent condition as regards leakage.

It is evident from an analysis of the diagrams in these tests,
that the economy was as high as could be expected under the
conditions of boiler pressure, ratio of cylinder areas, and cut-
off. For higher economy a higher pressure, larger ratio of
cylinder area, and earlier cut-off are required. It must be
noted, however, that the distribution is not the most perfect,
and there is rather a high back pressure in the L. P. cylinder.

ENGINE No. 46a

H.P. Head End

H.P. Crank End

-120
-100
-80
-60
-40
-20

- 0

-120
-100
-80

-60
40

-20

- 0

30-

20-

10-

0-

30-i

20-

10-

0-

L.P. Head End

L.P. Crank End

ENGINE No. 46b

H.P. Head End

H. P. Crank End

1—120

- 80

- 40

L. 0

M20

- 80

- 40

L 0

30-

20-

10-

L.P. Head End

30-

20-

10-

0-

L.P. Crank End

ENGINE No. 47.

Compound Condensing Engine.

H.P. CYLINDER.

L.P. CYLINDER.

Kind, of en°ine

Four valve

Number of cylinders . ...

1 1

Diameter of cylinder . ~ .

ins.

183V

44is

Diameter of piston rod . ....

ins.

Hi*

4i'5

Stroke of piston ........

ft.

6

0

Clearance

%

2.3

1.8

H. P. constant for one Ib. m. e. p. one

rev. per min

H.P.

.08728

.5584

Ratio of areas of cylinders . ...

1

6.398

Inside diameter of steam pipe . » .

ins.

8

14

Inside diameter of exhaust pipe , .

ins.

9

16

Condition of valves and pistons regard-

Practically

Considerable

ing leakage

tight

leakage

Data and Results of Feed -Water Tests.

TEST.
CONDITIONS REGARDING USE OF JACKETS.

A.
JACKETS

OFF.

B.
JACKETS

ON.

c.

JACKETS

ON.

D.
JACKETS

ON.

Character of steam . .-'«..-. .
Duration hrs.
Weight of dry steam consumed . Ibs.
Dry steam consumed per hour . Ibs.
Pressure in steam pipe above
atmosphere Ibs

4.817
42,147.

8,749.8

150.7

10.6
27.
60.31

67.79
9.87
366.8
332.52
689.32
12.69

Ordina
4.833
42,643.

8,823.3

151.1

9.4
27.3
60.54

66.15
10.63
349.52
359.31
708.33
12.45

ry

8,596.6
150.5

15.0
27.1
60.59

59.9
10.78
316.77
364.69
681.45
12.61

8,707.
151.4

19.4
28.0
60.33

57.13
11.39
300.85
383.71
684.56
12.72

Pressure in receiver above
atmosphere . . . ... Ibs.
Vacuum in condenser .... ins.
Revolutions per minute .
Mean effective pressure, H. P.
cylinder Ibs.
Mean effective pressure, L. P.
cylinder Ibs

Indicated horse-power, H. P.
cylinder .H.P.
Indicated horse-power, L. P.
cylinder H.P.
Indicated horse-power, whole
engine H.P.
Dry steam consumed per I. H.P.
per hr Ibs

185

186

ENGINE TESTS.

Measurements Based on Samnle Diaarams. Engine No. 47.

TEST.

^.

I

j.

H.P.CYL.

L.P. CYL.

H.P.CYL.

L.P.CYL.

Initial pressure above atmosphere Ibs.

145.2

9.8

146.1

9.

Corresponding steam-pipe or re-

ceiver pressure .... Ibs.

150.

10.6

149.2

95

Cut-off pressure above zero . Ibs.

149.2

20.

149.3

18.9

Release pressure above zero . Ibs.

42.5

5.3

41.

5.4

Mean effective pressure . . Ibs.

68.19

9.78

66.06

10.55

Back pressure at mid stroke

above or below atmosphere Ibs.

+10.9

-12.1

+10.1

-12.6

Proportion of stroke completes

at cut-off

.281

25

.263

.282

Steam accounted for at cut-off Ibs.

10.00

8.69

9.22

9.13

Steam accounted for at release Ibs.

10.34

9.54

9.59

9.61

Proportion of feed-water ac-

counted for at cut-off .

.788

.685

.740

.733

Proportion of feed-water ac-

counted for at release . .

.815

.752

.770

.771

Engine No. 47 is a horizontal tandem compound, with
jacketed cylinders and a reheater. The condenser is of the
siphon type with water supplied by gravity. The jacketing
applies to heads and barrel of the H. P. cylinder, and to the
heads but not the barrel of the L. P. cylinder. The reheater is
of the tubular type, and contains a sufficient area of surface to
superheat the steam passing to the L. P. cylinder, although
some of that entering the heater remains in a condensed
state, and is drawn off by a trap. The valves are all of the
gridiron type. The steam is furnished by horizontal tubular
boilers, and it was found by calorimeter test to be practically
dry. The valves and piston of the H. P. cylinder were found
in good condition. The steam valve at the head end of the
L. P. cylinder leaked badly, and the crank-end valve a consid-
erable amount; but as near as could be judged under these
circumstances the exhaust valves and piston were fairly tight.
The load was cotton machinery. Three tests were made with
different receiver pressures, and one test was made with
steam shut off from jackets and reheater.

On test B the water condensed in the jackets and reheater
tubes amounted to 681 Ibs. per hour, or 7.7% of the total.
This is included in the total quantity given in the table.

ENGINE No. 47. 187

A noticeable feature of these results is the systematic in-
crease in the steam consumption per H. P. per hour as the
receiver pressure was raised. This may have been due to the
increased leakage of the L. P. steam valves.

A comparison of the jacket tests reveals a gain due to the
jackets of 0.24 Ibs. per H. P. per hour, or about 2%. Although
this is not a marked difference, it is evident from an analysis
of the diagrams that the jackets had a considerable effect upon
the distribution of the steam, especially in increasing the
power developed by the L. P. cylinder and the quantity of
steam accounted for by the diagram for that cylinder.

UNIVERSITY
" CALIFO*

ENGINE No. 47a

H.P. Head End

-140
-120
-100
- 80
-60
-40
-20
I— 0

H.P. Crank End

-140
-120

-100
80

- 60
-40
-20

- 0

L.P. Head End

r 10

- 5

- 0

- 5
IO

L.P, Crank End

r 10

- 5

- 0

- 5

- 10

ENGINE No. 47b

H.P. Head End

-140
-120
-100
-80
-60
—40
-20
— 0

r-140
-120
-100
-80
-60
-40
-20
- 0

H.P. Crank End

L.P. Head End

L.P. Crank End

ENGINE No. 48.

Compound Condensing Engine.

H. P.

CYLINDER.

L. P.
CYLINDER.

Kind of engine
Number of cylinders

Four
1
28A

5
5
4

.185
1

Fairlj

valve
1
54
two 7
5
6

.682
3.69

- tight

Diameter of cylinder . ins.

Diameter of piston rod ins.

Stroke of piston ft.

Clearance %

Horse-power constant for one Ib. m.e.p.
one revolution per minute . . .H.P.
Ratio of areas of cylinders ....
Condition of valves and pistons regard-
in0" leakaee .

Data and Results of Feed - Water Tests.

TEST.
CONDITIONS REGARDING USE OF REHEATER.

A.
REHEATER

ON

B.
REHEAT'R

OFF.

c.

REHEATER

ON.

Character of steam
Duration hrs.
Total weight of feed-water consumed . Ibs.
Total feed-water consumed per hour Ibs.
Feed-water consumed per hour by air-
pump

Sup'd 12°
5.0
101,465.
20,293.

2,063.

Sup'd 13°
5.0
97,856.
19,571.2

2030.

Sup'd 20o
5.0
105,355.
21,071.

1,744.

Feed-water consumed per hour by
engine alone Ibs.
Pressure in steam pipe above atmos. Ibs.
Pressure in receiver above atmosphere Ibs.
Vacuum in condenser ins.

18,230.
125.9
11.4

27

17,541.2
121.5
10.1

27

19,327.

100.2
10.2

27 4

Revolutions per minute
Mean effective pressure, H. P. cylinder Ibs.
Mean effective pressure L. P. cylinder Ibs.
Indicated horse-power, H. P. cylinder H.P.
Indicated horse-power, L. P. cylinder H.P.
Indicated horse-power, whole engine . H.P.
Total feed-water consumed per I.H. P.
per hour Ibs.

77.
46.11
12.08
656.51
634.62
1,291.13

* 15.72

76.69
46.47
11.34
658.90
593.31
1,252.21

15.63

76.68
45.29
12.22
642.16
639.57
1,281.73

16.44

Feed-water per I. H. P. per hour,
engine alone Ibs

14 12

14.01

15 08

* This refers to steam used by the engine alone.

190

ENGINE No. 48.

191

Measurements based on Sample Diagrams.

TEST.

A.

B.

c.

H.P.CY.

L.P.Cv.

H.P.CY.

L.P.CY.

H.P.CY.

L.P.CY.

Initial pressure above

atmosphere . . . Ibs.

119.5

13.1

113.3

11.8

94.8

10.

Corresponding steam

pipe or receiver

pressure .... Ibs.

127.

12.3

121.

9.8

100.

10.3

Cut-off pres. above zero Ibs.

115.3

22.

112 5

20.7

93.

18.8

Release pres. above zero Ibs.

38.2

8.3

37.7

7.7

39.

8.5

Mean effective press. . Ibs.

46.62

12.29

46.99

11.5

45.11

12.25

Back pressure at mid

stroke above or be-

low atmosphere . Ibs.

+18.5

—10.7

+16.5

—10.7

+13.7

-11.3

Proportion of stroke

*'

completed at cut-off

.294

.326

.31

?326

.432

.416

Steam accounted for

«

at cut-off .... Ibs.

11.18

10.66

11.99

10.33

12.41

12.18

Steam accounted for

at release . . . Ibs.

12.27

11.55

12.63

11.

13.04

12.25

Proportion of feed

water accounted for

at cut-off . . .

.792

.755

.856

.737

.823

.808

Proportion of feed

water accounted for

at release . . .

.869

.818

.901

.785

.865

.812

Engine No. 48 is a horizontal cross compound, with un-
jacketed cylinders and a reheating receiver. The valves are
plain slides. The condenser is of the jet type with steam-
driven air-pump, the steam used for which was determined
and allowed for. The boilers are of the vertical fire-tube type,
furnishing slightly superheated steam. The crank end exhaust
valve of the H. P cylinder leaked considerably, but with this
exception the valves and pistons were practically tight. The
load was cotton machinery.

A comparison of tests A and C shows the effect of two
widely different pressures upon the economy, one being 125.9
Ibs., and the other 100.2 Ibs. The reduction of pressure in-
creased the consumption from 14.12 Ibs. per I. H. P. per hour
to 15.08 Ibs., or nearly 7 %.

Test B as compared with test A exhibits the effect of
shutting off the reheater. There is a slight loss of economy ;
but as the difference is within the limits of errors of measure-

192 ENGINE TESTS.

ment and accidental difference of condition, the most that can
be said is that the economy produced by the reheater was in
this case inappreciable. On test A there was 648 Ibs. of steam
per hour condensed and drawn off from the reheater tubes.
This is 4 % of the quantity used by the engine. The effect of
the heat derived from this source is seen in the increased
power developed by the L. P. cylinder, and the increase in the
amount of steam accounted for in the L. P. cylinder as com-
pared with that in the H. P. cylinder.

The comparatively large amount of steam used by the air-
pump is noticeable, being about 10 % of the entire quantity
on Test A.

I2Q— i

100-

80-

60-

40-

20-

0-

ENGINENo. 48a

H.P. Cyl. Head End

H.P. Crank End

-120
-100

- 80

- GO

- 40

- 20

- 0

UP. Head End

- 15

- 10

5
0

- 5
L 10

10-

6-
0

5-
10-

L.P. Crank End

ENGINE No. 48b

120-
100-
80-
60-
40-
20-
0-

H.P. Head End

H. P. Crank End

-120
100
30
60
40

- 20

- 0

L.P. Head End

15-

10
6-
0-
6-

10-

L.P. Crank End

ENGINE No.48c

100-
80-
60-
40
20-
0-

H.P. Head End

H.P. Crank End

100
80
60
40
20
0

L.P. Head End

5-
0-
5-
10-

L.P. Crank End

ENGINE No. 49.

Compound Condensing Engine.

H.P.
CYLINDER.

L. P.
CYLINDER.

Kind of engine . . . .... . .
Number of cylinders

Four valv
1

B (Corliss)
1

Diameter of cylinder . , . .' . . ins.
Diameter of piston rod ..... ins.
Stroke of piston ........ ft.
Clearance %

24
6A

5
3

44
51
5
4i

H. P. constant for 1 Ib. m. e. p. one
revolution per minute .... H.P.
Ratio of areas of cylinders ....
Condition of valves and pistons regard-
ing leakage

.1337

1
Some
leakage

.457
3.43
Fairly
tight

Data and Results of Feed - Water Test.

Character of steam . . . . . . . ."

Duration . . .

Weight of feed-water consumed . . . .

Feed-water consumed per hour ....

Pressure in steam pipe above atmosphere .
Pressure in receiver above atmosphere .
Vacuum in condenser . .? . .... .

Revolutions per minute ......

Mean effective pressure, H. P. cylinder .
Mean effective pressure, L. P. cylinder
Indicated horse-power, H. P. cylinder
Indicated horse-power, L. P. cylinder .
Indicated horse-power, whole engine .
Feed-water consumed per I. H. P. per hour

Ordinary

4.75

hie.

58.832

Ibs.

12,385.6

Ibs.

115.4

Ibs.

6.8

Ibs.

28.4

ins.

71.3

rev.

47.93

Ibs.

12.71

Ibs.

457.9

H.P.

415

H.P.

872.9

H.P.

14.18

Ibs.

Measurements based on Sample Diagrams.

H.P.

CYLINDER.

L. P.
CYLINDER.

Initial pressure above atmosphere . ."
Corresponding steam-pipe and receiver
pressure .
Cut-off pressure above zero . . . ' .
Release pressure above zero ....
Mean effective pressure
Back pressure at mid stroke above or
below atmosphere . .

Ibs.

Ibs.
Ibs.
Ibs.
Ibs.

Ibs.

100.9

114
104.4
36.3
49.03

+12 7

9.3

10.6
19.
8.6
12.71

—11.8

Proportion of stroke completed at cut-
off

.33

.404

Steam accounted for at cut-off . . .
Steam accounted for at release .
Proportion of feed-water accounted for
at cut-off

Ibs.
Ibs.

12.28
12.95

.866

10.82
11.78

.763

Proportion of feed-water accounted for
at release . . ..... . .

.913

.831

196

ENGINE No. 49. 197

Engine No. 49 is a cross compound horizontal engine with
jacketed cylinders, and a jet condenser operated by a direct con-
nected air-pump. The jacket spaces are of the kind which allow
the steam to pass through them before entering the steam chest
of either cylinder, and the water of condensation drains to waste.
Steam is supplied from water-tube boilers through a pipe about
100 feet in length, which is trapped near the throttle valve.
Steam lost by condensation in this pipe, and that used for cer-
tain heating purposes, was determined independently, and
allowed for. The front-end steam valve of the high-pressure
cylinder leaked badly. With this exception, the valves and
pistons throughout were in fairly good condition. The load
was cotton machinery.

Considering the proportion which is borne by the stearn
accounted for to the feed-water consumption in the high-pres-
sure cylinder, the result of this test, 14.18 Ibs. per. I. H. P.
per hour, must be considered as an exceptionally good per-
formance.

ENGINE No.49

100-
80-

60-
40-
20-

H.P. Head End

H. P. Crank End

-100

- 80

- 60

- 40

- 20
— 0

L.P. Head End

- 10

- 5
0

- 5

- 10

L.P. Crank End

- 10

- 5
- 0

- 5

- 10

ENGINE No. 50.

Compound Condensing Engine.

H. P.

CYLINDER.

L. P.
CYLINDER

Kind of engine . . . . . . . . .

Four valv
1

61
2.5

.1631
1

Some
leakage

e (Corliss)
1
431
5H
6
4

.5577
3.42
Fairly

tight

Number of cylinders \
Diameter of cylinders ins.
Diameter of piston rod ins.
Stroke of piston ft.
Clearance .... x.

H. P. constant for 1 Ib. m. e. p. one rev-
olution per inin H.P.
Ratio of areas of cylinders

Condition of valves and pistons regarding
leakage

Data and Results of Feed -Water Test.

Character of steam '.. .
Duration .

. . Superheati
5

3d 30°
hrs.
Ibs.
Ibs.
Ibs.
Ibs.
ins.

Ibs.
Ibs.
H.P.
H.P.
H.P.
Ibs.

Weight of feed-water consumed
Feed-water consumed per hour . . . . . . ...
Pressure in steam pipe above atmosphere . . . . .
Pressure in receiver above atmosphere ....

. . 53,003
. . 10,600.7
. . 108.1
'. . 13 4

Vacuum in condenser ' . . . •

27 2

Revolutions per minute

Mean effective pressure H P cylinder

. . 61.4

35 77

Mean effective pressure, L. P. cylinder
Indicated horse-power H P cylinder

. . 12.86

358 2

Indicated horse power Ij P cylinder

440 2

Indicated horse-power, whole engine
Feed-water consumed Der I. H. P. per hour

. . 798.4
13.28

Measurements based on Sample Diagrams.

H.P.
CYLINDER.

L. P.
CYLINDER.

Initial pressure above atmosphere .
Corresponding steam-pipe and receiver
pressure

Ibs.
Ibs

94.9

108

12.8
13 4

Cut-off pressure above zero ....
Release pressure above zero ....
Mean effective pressure

Ibs.
Ibs.
Ibs

102:6
28.1
35 78

22.4
6.9

12 72

Back pressure at mid stroke, above or
below atmosphere

Ibs

+ 16 3

— 12 4

Proportion of stroke completed at cut-off
Steam accounted for at cut-off . . .
Steam accounted for at release . . .
Proportion of feed-water accounted for
at cut-off
Proportion of feed-water accounted for
at release

Ibs.
Ibs.

.274
11.81
11.97

.889
.901

.27
10.23
10.87

.77
.819

199

200 ENGINE TESTS.

Engine No. 50 is a cross compound engine with horizontal
steam jacketed cylinders and a jet condenser operated by a
direct connected air-pump. The jacket of the L. P. cylinder
forms a thoroughfare through which the steam is supplied to
the steam chest, the steam being admitted through the bottom.
The jacket of the H. P. cylinder drains into the receiver. The
drip of the receiver and of the low-pressure jacket passes to a
pump operated by the engine, and thence to flue heaters, or
" regenerators " as they are called, which are located in the flue
of the boilers. The steam generated in these heaters returns
to the receiver. By this means the low-pressure cylinder
receives benefit from some of the heat which would otherwise
escape from the boilers to the chimney. Steam is supplied
from vertical boilers, which superheat. The exact amount of
superheating was not determined ; but from the operation of
boilers of similar type, the temperature was probably 30° above
the normal. The piston of the high-pressure cylinder leaked
considerable, but the piston of the low-pressure cylinder and
the valves of both were in good condition. The load was that
of a cotton mill.

The results of this test are interesting on account of the
means provided for reheating the steam and re-evaporating the
jacket water for the use of the low-pressure cylinder, employ-
ing for this purpose the heat of the waste gases of the boilers.
Comparing this test with that made on Engine No. 49, where
no such provision was made, the difference is quite marked,
being .9 of a pound per I. H. P. per hour, or nearly 7%. It is
difficult to determine by this comparison how much, if any,
effect was produced by the reheating process, because of the
difference in the condition of the steam; and, furthermore,
because there was quite a difference in the degree of expansion,
the cut-off in the high-pressure cylinder of one engine being
.33, and in the other .27. The effect of the reheating is not
sufficiently marked to show in the analysis of the diagrams.
It appears that there was no more steam accounted for in the
low-pressure cylinder in one case than in the other. A greater
quantity might be expected if there was a marked effect pro-
duced by the reheating.

ENGINE No. 50

100-
80-
60-
40-
20-
0—

H.P. Head End

H.P. Crank End

100
-80
-60
— 40
-20
- 0

L.P. Head End

L.P, Crank End

ENGINE No. 51.

Compound Condensing Engine.

H. P.
CYLINDER.

L. P.
CYLINDER.

Kind of engine . , . ....
Number of cylinders ......
Diameter of cylinder ins

Four

1
18

valve
1

48i

Diameter of piston rod .... ins.
Stroke of piston . . ft

31
4

41
4

Clearance .... %

2

it

H. P. constant for one Ib. m. e. p. one
revolution per minute . . . . H.P.
Ratio of areas of cylinders ....
Condition of valves and pistons regard-
ins: leakage .

.0604
1

Some
leakaa-e

.4412
7.3

Some
leakage

Data and Results of Feed -Water Tests.

TEST.

A.

B.

C.

Character of steam, degs. superh'g

15.7

16.4

12.2

Duration hrs

5

5

5

Weight of feed-water consumed . . Ibs.

41,210

39,583

39,174

Feed-water consumed per hour . . .

8,242

7,916.6

7,834.8

Pressure in steam pipe above atmos.

149.7

150.4

150.2

Pressure in receiver Ibs.

5.4

9.1

12.9

Vacuum in condenser ins.

26.9

26.4

26.6

Revolutions per minute rev.

80.04

80.14

80

Mean effective pressure, H. P. cylinder Ibs.

72.44

65.89

61.9

Mean effective pressure, L. P. cylinder Ibs.

9.03

9.59

10.2

Indicated horse-power, H.P. cylinder. H.P.

350.9

318.9

299.3

Indicated horse-power, L. P. cylinder . H.P.

390.6

339.2

359.8

Indicated horse-power, whole engine . H.P.

670.5

658.1

659.1

Feed-water cons, per I. H. P. per hour Ibs.

12.29

12.03

11.89

Measurements Based on Sample Diagrams.

TEST.

i

L.

(

H.P.

L.P.

H.P.

L.P.

Initial pressure above atmosphere . . Ibs.

143.9

5.2

143.

14.5

Corresp. steam-pipe and receiver pres. Ibs.

151

*5.5

150.5

*12.8

Cut-off pressure above zero .... Ibs.

149

15.4

145.9

24.7

Release pressure above zero .... Ibs.

42.5

5.2

43.

5.2

Mean effective pressure Ibs.

72.7

9.08

62.27

10.23

Back pressure at mid stroke above or

below atmosphere Ibs.

+ 6

-13.1

+ 16.5

-13

Proportion of stroke completed at cut-off

.285

.323

.285

.176

Steam accounted for at cut-off . . . Ibs.

9.54

9.07

9.21

7.96

Steam accounted for at release . . . Ibs.

9.62

8.88

9.58

8.43

Proportion of feed-water accounted for

at cut-off ....

.77

.732

.769

.654

Proportion of feed- water accounted for

at release

.776

.716

.8

.704

* Not corrected.

NOTE. — The weight of steam condensed in all the jackets averaged, for the
three trials, 9.5 % of the total steam consumed ; and this is included in the
quantities given.

202

ENGINE No. 51. 203

Engine No. 51 is a horizontal cross compound, with jacketed
cylinders and a reheater. The condenser is of the siphon type,
and water is supplied by gravity. Both the barrel and the
heads of the high-pressure cylinder are jacketed, but only the
barrel of the L. P. cylinder. The reheater has sufficient sur-
face to superheat the steam, although not sufficient to prevent
some water condensing in the bottom of the shell, from which
it is drawn away by a trap. The jackets are drained by traps
which discharge to waste. The valves are all of the gridiron
type. Steam is supplied from vertical boilers which super-
heat. The piston of the H. P. cylinder was found to show
some leakage. The low-pressure exhaust valve at the crank
end leaked quite badly. The piston of the L. P. cylinder and
the remaining valves were in good condition. Three tests
were made, using three different receiver pressures.

These tests are of interest on account of the unusual ratio
of volumes of the cylinders. This ratio is about the same as
that which is common practice between the low-pressure and
high-pressure cylinder of a triple expansion engine. This
large ratio taken in conjunction with the high initial pressure,
and the fact that the steam was slightly superheated, furnishes
an explanation for the economical results obtained, which are
unusual.

Comparing the three tests together, it appears that there was
a gradual improvement produced by increasing the receiver
pressure, the best result being obtained when that pressure was
the highest.

In this connection, it is noticeable that as the receiver pres-
sure increased, and the cut-off in the low-pressure cylinder
became less, the steam accounted for by the low-pressure
cylinder became less.

ENGINE No.SIa

140-
120-
100-
80-
60-
40-
20-
0-

H.P. Head End

H.P. Crank End

-140
120
100
•80
GO
•40
-20
- 0

L.P. Head End

L.P. Crank End

140-

120-

100-

80-

60-

40-

20-

0-

ENGINENo.SIc

H. P. Head End

H.P. Crank End

-140
-120
-100

- 80
-60
-40
-20

- 0

L.P. Head End

L.P. Crank End

ENGINE No. 52.

Compound Condensing Engine.

H.P.
CYLINDER.

L. P.

CYLINDER.

Kind of engine

Four

^alve

Number of cylinders
Diameter of cylinder . ins.

Diameter of piston rod ins.
Stroke of piston .... ft

2
14TV
34
4

2
36*

one 3k
one 4^
4

Clearance %

2

2£

H. P. Constant for one Ib. m.e.p., one
rev. per minute H.P.
Ratio of areas of cylinders ....
Condition of valves and pistons regard-
ins: leakage .

.0367 each
1

Some leakage

.2456 each
6.69 both

Some leakage

Data and Results of Feed -Water Tests.

TEST.
JACKETS ON OR OFF.

A.
ON.

B.
ON.

C.
ON.

D.
OFF.

Character of steam ....

Ordinary

Ordinary

Ordinary

Ordinary

Duration hrs.

5.0

5.06

5.03

4.5

Weight of feed-water consumed Ibs.

47,045.0

49,720.0

48,389.0

43,321.0

Feed-water consumed per hour Ibs.

9,409.0

9,812.5

9,614.4

9,626.9

Pres. in steam pipe above atmos. Ibs.

144.2

144.1

143.8

144.1

Pres. in receiver above atmos. Ibs.

4.9

8.6

12.2

12.3

Vacuum in condenser .... ins.

25.3

25.2

25.0

24.9

Revolutions per minute . . . rev.

77.45

76.65

76.86

78.89

Mean effective pressure, H.P. cyl. Ibs.

61.12

60.82

57.29

60.53

Mean effective pressure, L.P. cyl. Ibs.

9.76

10.6

11.0

9.66

Indicated horse-power, H.P. cyl. H.P.

347.63

342.48

323.48

350.79

Indicated horse-power, L.P. cyl. H.P.

371.22

398.84

415.29

374.41

Indicated H. P. whole engine . H.P.

718.85

741.32

738.77

725.2

Feed-water consumed per I. H.P.

per hour Ibs.

13.09

13.23

13.01

13.27

Measurements based on Sample Diagrams.

TEST.

<

r

>.

JACKETS ON OR OFF.

ON.

ON.

OFF.

OFF.

Initial pressure above atmosphere . . Ibs.
Corresponding steam-pipe and receiver
pressure above atmosphere . . Ibs.
Cut-off pressure above zero .... Ibs.
Release pressure above zero .... Ibs.
Mean effective pressure Ibs

H.P.
139.7

145.0
140.0
41.3

57 64

L.P.

13.0

12.3
22.4
5.6

11 07

H. P.
139.9

144.5

140.0
44.0
60 3

L. P.
11.7

12.8
21.4
5.2

9 58

Back pressure at mid stroke above or
below atmosphere Ibs.

+13.8

-12.2

+14.1

—12.2

Proportion of stroke completed at cut-off
Steam accounted for at cut-off . . . Ibs.
Steam accounted for at release . . . Ibs.
Proportion of feed-water ace. for at cut-off
Proportion of feed-water accounted for
at release

.268
8.48
9.26
.651

.712

.236
10.23
10.62
.786

.816

.293
9.75
10.27
.734

.774

.213
8.71
9.79
.655

.73

206

ENGINE No. 52. 207

Engine No. 52 is a pair of horizontal tandem compounds,
having jacketed cylinders and reheating receivers, the con-
densers being of the siphon type, to which water is supplied
by gravity. The H. P. cylinders are jacketed all over, but the
L. P. cylinders have only the barrels jacketed. As in the case
of Engine No. 51, the reheaters are provided with sufficient
surface to superheat the steam passing to the low-pressure
cylinders, the water which remains being trapped. The valves
are all of the gridiron type. Steam is supplied by horizontal
return tubular boilers, and at the throttle valves it contained
.1 of 1 % of moisture. The H. P. pistons leaked to some ex-
tent, and the head-end exhaust valve of the left-hand low-
pressure cylinder leaked a considerable amount. The pistons
of the H. P. cylinder and the remaining valves were fairly
tight. The load was cotton machinery.

Three trials were made with three different receiver pres-
sures, and a fourth trial with steam shut off from the jackets
and the reheating tubes.

Comparing the results of these tests with those made on
Engine No. 51, which is of the same general type and of
about the same power, but having only half the number of
cylinders, there is a striking difference. This engine did not
have the benefit of superheated steam as did Engine No. 51,
and this difference in the conditions must be taken into account ;
but it is hardly possible that the whole of the difference, which
is about 9 %, could be produced in this way. There may be
some difference, also, in the amount of leakage of the two en-
gines. Engine No. 51 had the benefit of the best vacuum.
Making all allowances for these differences, it is quite certain
that the size of the cylinders had some effect upon the results.
The action of the steam in the cylinders is quite different in
No. 52 from what it is in No. 51 ; but it will be noticed that
steam accounted for in the low-pressure cylinders is greater than
that shown in the high pressure cylinders, whereas in Engine
No. 51 the contrary is true.

Comparing Test " C " with jackets on, and Test " D " with
jackets off, the difference in the economy shown is only .26 of

208 ENGINE TESTS.

a pound, or about 2 %. The nature of the action which the
jackets produced is shown in the analysis of the diagrams.
With the jackets on, the steam accounted for in the low-pres-
sure cylinder is the greatest ; whereas, with the jackets off, the
steam accounted for in that cylinder is the least.

Another noticeable thing in the action of the jackets is in
the distribution of the power between the cylinders. With
jackets on, the low-pressure cylinders developed 92 horse-
power more than the high-pressure cylinders, or about 30 °/0 ;
whereas, with jackets off, the increase was only 24 horse-power,
or about 7 %.

NOTE. — The quantity of steam condensed in the jackets on the first three
trials was respectively, 11.4 %, 10.8 %, and 10.8 % of the total quantity con-
sumed ; and these are included in the figures given in the tables.

ENGINE No. 52c

140-
120-
100-
80-
60-
40-
20-
0-

R.H.H.P. Head End

R.H.H.P. Crank End

-140

120

100

- 80

60

40

20

0

10-

5 —
0-
5-
10

R.H.L.P. Head End

R.H.L.P. Crank End

ENGINE No. 52c

I40-,

120-

100-

80-

60-

40-

20-

0-

L.H.H.P. Head End

L.H.H.P. Crank End

140
120
100
80
60
40
20
- 0

L.H.L.P. Head End

15-
10-
5-

o-

5-

10-

L.H.L.P. Crank End

ENGINE No. 52d

140—

120-

100-

80-

60-

40-

20-

0-

R.H.H.P. Head End

R.H.H.P. Crank End

-140
—120
-100

- 80

— 60

- 40

— 20

— O

15-
10-
5—
0—
5-
10-

R.H.L.P. Head End

R.H.L.P. Crank End

- 15

— 10

- 5

— 0

— 5

- 10

ENGINE No. 52d

140—

ISO—

100-

80-

60-

40-

20-

0-

L.H.H.P. Head End

L.H.H.P. Crank End

-140
120
100
80
-60
-40

- 20

- 0

L.H.L.P. Head End

15
10
5
0
5
10

15—
10-

5-

O-

5

10-

L.H.L.P. Crank End

ENGINE No. 53.

Compound Condensing Engine.

H.P. CYLINDER.

L.P. CYLINDER.

Kind of engine

Four vah

1
18

31

4
3

.0608
1

Fairly tight

re (Corliss)
30

4*
3

.1685

2.77

Fairly tight

Number of cylinders
Diameter of cylinder ins

Diameter of piston rod ins

Stroke of piston ft.
Clearance %
H. P. constant for one Ib. m. e. p., one
rev. per min H.P.
Ratio of areas of cylinders ....
Condition of valves and pistons regard-
in0" leakage

Data and Results of Feed -Water Tests.

Character of steam

Duration

Weight of feed- water consumed

Feed-water consumed per hour

Pressure in steam pipe above atmosphere

Pressure in receiver above atmosphere

Vacuum in condenser

Revolutions per minute

Mean effective pressure, H. P. cylinder

Mean effective pressure, L. P. cylinder

Indicated horse-power, H. P. cylinder

Indicated horse-power, L. P. cylinder

Indicated horse-power, whole engine

Feed-water consumed per I. H. P. per hour

Ordinary

3.0

hrs.

14,195.0

Ibs.

4,731.7

Ibs.

114.9

Ibs.

15.4

Ibs.

25.6

ins.

65.5

rev.

35.07

Ibs.

14.27

Ibs.

142.1

H.P.

157.6

H.P.

299.7

H.P.

15.78

Ibs.

Measurements based on Sample Diagrams.

H. P.

CYLINDER.

L.P.
CYLINDER.

Initial pressure above zero
Cut-off pressure above zero
Release pressure above zero
Mean effective pressure

Ibs.
Ibs.
Ibs.
Ibs

111.9
111.7
30.8
36 65

14.6
33.2

8.7
14 52

Back pressure at mid stroke, above or be-
low atmosphere
Proportion of stroke completed at cut-off .
Steam accounted for at cut-off ....
Steam accounted for at release ....
Proportion of feed-water accounted for at
cut-off

Ibs.

Ibs.
Ibs.

+ 16.7
.238
11.31
9.47

717

- 11.8

13.01
10.76

60

Proportion of feed-water accounted for at
release . ...

825

682

213

214 ENGINE TESTS.

Engine No. 53 is a horizontal tandem compound, with un-
jacketed cylinders and jet condenser operated by an indepen-
dent air-pump. The steam from the air-pump was taken from
an auxiliary boiler. The boilers are of the water-tube vertical
type, furnishing steam slightly superheated. The steam passes
through a reservoir at the engine, which is drained by a trap
discharging to waste. The valves and pistons of both cylin-
ders were found to be in fairly good condition throughout.
The load on the engine was rubber-grinding machinery and
somewhat variable in its character.

The economy shown by this test, 15.78 Ibs. per I. H. P. per
hour, is rather low compared with other compound engines of
this type. The explanation of this result is found in part, at
least, in the small ratios of volumes of the two cylinders. The
diagrams show the variable character of the load.

ENGINE No. 53

H.P. Head End

100
80
60
40
20
0

100 -|
80-
60-
40-
20-
0-

H.P. Crank End

10-
5-
0-
5-
10-

L.P. Head End

L.P. Crank End

r-15
10

h- 5
0
5
10

ENGINE No. 54.
Compound Non-Condensing Engine.

H. P. CYLINDER.

L. P. CYLINDER.

Kind of engine •'
Number of cylinders
Diameter of cylinder . . ... . ins.
Diameter of piston rod . . . ... ins.
Stroke of piston . . . . . . ." . ins.
Clearance . . %

Single
1
12
2i
13
11

.0073
1

Some 1

valve

1
20
2*
13
8

.0205
2.81

eakage

H.P. constant for one Ib. m.e.p., one
revolution per minute . . . .H.P.
Ratio of areas of cylinders ....
Condition of valves and pistons regard-
ing leakage

Data and Results of Feed -Water Tests.

TEST.

A.

B.

c.

Character of steam

Ordinary

Ordinary

Ordinary

Duration hrs.
Weight of feed-water consumed . . Ibs.
Feed-water consumed per hour . . . Ibs.
Pressure in steam pipe above atmos. . Ibs.
Pressure in receiver above atmosphere Ibs.
Revolutions per minute rev

5.0
17,918.0
3,583.6
166.9
28.2
275 7

5.0
19,815.0
3,963.0
166.8
46.3
271 2

5.0
25,730.0
5,146.0
164.6
60.6
273 4

Mean effective pressure, H. P. cylinder Ibs.
Mean effective pressure, L. P. cylinder Ibs.
Indicated horse-power, H. P. cylinder H.P.
Indicated horse-power, L. P. cylinder H.P.
Indicated horse-power, whole engine . H.P.
Feed-water consumed per I. H. P. per
hour Ibs.

29.06
7.94
58.5
44.88
103.37

24.99

48.37
16.5
95.77
91.74
187.51

21.14

52.31

24.58
104.41
137.77

242.18

21.25

Measurements based on Sample Diagrams, Test B.

H.P.
CYLINDER.

L. P.
CYLINDER.

Initial pressure above atmosphere . .
Corresponding steam-pipe and receiver
pressure '.
Cut-off pressure above zer > .
Release pressure above zero . . . ' .
Mean effective pressure . . . ...
Back pressure at mid stroke above
atmosphere »
Proportion of stroke completed at cut-
off

Ibs.

Ibs.
Ibs.
Ibs.
Ibs.

Ibs.

157.3

168.5
147.5

77.4
47.98

41.6
.479

43.0

46.0
39.9
23.9
16.36

2.00
.499

Steam accounted for at cut-off . . .
Steam accounted for at release . . .
Proportion of feed-water accounted for
at cut-off

Ibs.
Ibs.

15.73
15.41

.744

14.71
14.51

.696

Proportion of feed- water accounted for
at release

.728

.686

216

ENGINE No. 54. 217

Engine No. 54 is a vertical cross compound with unjacketed
cylinders. Each cylinder has a single balanced slide valve,
and the speed is controlled by a shaft governor operating on
the H. P. valve. The steam is drawn from water-tube boilers
through a considerable length of pipe, having headers and
separators which were thoroughly drained, and a calorimeter
attached near the engine showed that it was practically dry.
Steam condensed from the pipes was trapped and properly
allowed for. The load consisted of two dynamos located on
the engine shaft. The valves of both cylinders leaked a small
amount, and the piston of the H. P. cylinder leaked consider-
ably at full pressure. The low-pressure piston was tight.
Three tests were made with three different loads.

In these tests there is substantial agreement between the
results of tests " B " and " C " ; the former being made under
conditions of a medium load, and the latter under what would
be considered an overload. This reveals the advantage of com-
pounding in engines of this class, where by this means the
benefits of expansion in the engine as a whole are realized with-
out suffering the losses produced in either cylinder due to
early cut-offs.

ENGINE No. 54a

160-

120-

80-

40-

0-

H.P.Top

-120

-80

40

— 0

H.P. Bottom

30-

20-

10-

0-

L.P. Top

30-

20-

10-

0-

L.P. Bottom

ENGINE No. 54b

H.P. Top

160-
120-

80-

40-

0—

- 160
-120
-80
-40
— 0

H.P. Bottom

60-
40-
30-
20-
10-
0-

UP. Top

50-

40-

30-

20-

10-

0-

L.P. Bottom

ENGINE No. 54c

H.P.Top

-160

-120
-80

-40

L- 0

160-^
120-
80-
4O-
0-

H.P. Bottom

60n

50-
40-
30-
20-
10-
0-

60^
60-
40-
30-
20-
10-
0-

L.P. Top

. Bottom

ENGINE No. 55.

Compound Condensing Engine.

H.P.
CYLINDER.

L. P.
CYLINDER.

Kind of engine

Four valv^ I'flnrlissl

Number of cylinders

1

1

Diameter of cylinder ins.

28

56

Diameter of piston rod .... ins.

51

6*

Stroke of piston ft.

5

5

Clearance %

3.1

4.3

H.P. Constant for one Ib. m. e. p.,

one rev. per min H.P.

.1827

.7413

Ratio of areas of cylinders .

1

4.06

Condition of valves and pistons

regarding leakage , . . .

Practically tight

Data and Results of Feed -Water Test.

Character of steam '

Or

dinary
hrs.
Ibs.
Ibs.
Ibs.
Ibs.
ins.
rev.
Ibs.
Ibs.
H.P.
H.P.
H.P.
Ibs.

Duration

9 5

Weight of feed-water consumed
Feed-water consumed per hour
Pressure in steam pipe above atmosphere
Pressure in receiver above atmosphere (not verified) .
Vacuum in condenser

. . 216,002.45
. . 22,737.1
. . 151.5
. . 11.8
26 8

Revolutions per minute

75 18

Mean effective pressure, H. P. cylinder .....

. . 61.76
15 53

Mean effective pressure, L P cylinder

Indicated horse-power, H. P. cylinder

848 27

Indicated horse-power, L. P. cylinder
Indicated horse-power, whole engine
Feed-water consumed per I. H. P. per hour ....

. . 865.58
. . 1,713.85
. . 13.27

Measurements based on Sample Diagrams.

H.P.
CYLINDER.

L. P.
CYLINDER.

Initial pressure above atmosphere .
Corresponding steam-pipe or receiver
pressure

Ibs.
Ibs

1430
151 0

15.5
*11 8

Cut-off pressure above zero ....
Release pressure above zero ....
Mean effective pressure
Back pressure at mid stroke above or
below atmosphere .

Ibs.
Ibs.
Ibs.

Ibs

152.3
44.4

61.53

+ 20 0

22.0
9.5

15.84

— 11 5

Proportion of stroke completed at cut-
off

326

421

Steam accounted for at cut-off . . .
Steam accounted for at release .
Proportion of feed-water accounted for
at cut-off

Ibs.
Ibs.

10.84
10.84

817

10.98
10.85

828

Proportion of feed-water accounted for
at release .... .'

817

818

* Not verified.
221

222 ENGINE TESTS.

Engine No. 55 is a cross compound with horizontal un-
jacketed cylinders and a reheating receiver. The steam is
exhausted into a surface condenser operated by an independent
steam-driven air and circulating pump. The quantity of steam
used by the condenser was determined independently and
allowed for. The steam is taken from vertical water-tube
boilers in a slightly superheated state. The valves and pistons
of both cylinders were found to be in excellent condition
throughout, with practically no leakage. The load was an
electric generator located on the main shaft, furnishing current
for motors in a cotton mill. The steam condensed in the re-
heater coil amounted to three and one half per cent of the total
weight of steam passing the throttle valve. This is included
in the quantities given in the table.

A noticeable feature in these results is the close agreement
between the four quantities given for steam accounted for by
the indicator. Three of these are practically equal, and the
fourth differs only one per cent.

ENGINE No.55

140-

120-

100-

80-

60-

40-

20-

0-

H.P. Head End

H.P. Crank End

-140

— 120
-100

- 80

- 60
-40

— 20

— 0

L.P. Head End

— !6

- 10

— 5

- 0

— 5

- 10

L.P. Crank End

i- 15

— 10

- 5

- 0

— 5

- 10

ENGINE No. 56.

Compound Condensing Engine.

H.P.
CYLINDER.

L. P.
CYLINDER.

Kind of engine

Four valv

1
22|

4i

3.5
3

.0799
1
Some
leakage

e (Corliss)
1
42
J4i
[«
3.5
4

.2897
3.63
Some
leakage

Number of cylinders ......
Diameter of cylinder ins.

Diameter of piston rod ins

Stroke of piston ft.
Clearance .... . %

H. P. constant for 1 Ib. in. e. p. one
revolution per minute . . . . H.P.
Ratio of areas of cylinders ....
Condition of valves and pistons regard-
ing leakage

Data and Results of Feed -Water Test.

Character of steam ,..-....

Duration 5.0

Weight of feed-water consumed . . . . . >. . , . -. . 60,636
Feed- water consumed per hour 12,127.3

Pressure in steam pipe above atmosphere
Pressure in receiver above atmosphere .
Vacuum in condenser . . . . . .

Revolutions per minute

Mean effective pressure, H. P. cylinder .
Mean effective pressure, L. P. cylinder . .
Indicated horse-power, H. P. cylinder . .
Indicated horse-power, L. P. cylinder . .
Indicated horse-power, whole engine .• .
Feed-water consumed per I. H. P. per hour

107.8
11.0
25.2
120.2
45.07
11.30
432.93
394.12
827.05
14.67

Ordinary

hrs.

Ibs.

Ibs.

Ibs.

Ibs.

ins.

rev.

Ibs.

Ibs.
H.P.
H.P.
H.P.

Ibs.

Measurements based on Sample Diagrams.

H. P.
CYLINDER.

L. P.
CYLINDER.

Initial pressure above atmosphere .

Ibs.

102.2

11.1

Corresponding steam-pipe and receiver

pressure . •_ . . . '

Ibs.

107.0

11.0

Cut-off pressure above zero . .' . ."

Ibs.

99.0

20.3

Release pressure above zero . . / .

Ibs.

36.0

8.5

Mean effective pressure . . . . ..

Ibs.

44.93

11.29

Back pressure at mid stroke above or

below atmosphere

Ibs.

+11.6

-10.5

Proportion of stroke completed at cut-off

.331

.362

Steam accounted for at cut-off . . . '

Ibs.

11.87

10.46

Steam accounted for at release . . .

Ibs.

12.91

11.79

Proportion of feed-water accounted for

at cut-off ....

.813

.716

Proportion of feed-water accounted

for at release

.88

.806

224

ENGINE No. 56. 225

Engine No. 56 is a tandem compound with horizontal jack-
eted cylinders and reheating receiver. Steam is supplied to
the bottom of each cylinder, and the jacket spaces form a
thoroughfare through which it passes to the steam chest at the
top. The jackets are drained by traps which discharge to
waste. A jet condenser is used, with an independent steam-
driven air-pump, which is supplied from an independent boiler.
Steam is taken from horizontal return tubular boilers, and
it contained 0.8 °]0 of moisture at a point near the throttle
valve. The valves and pistons were found to be in fair condi-
tion, but not the best. The load consisted of an electric gene-
rator placed on the driving-shaft, which for the test supplied
current to a water rheostat.

This is an example of a Corliss engine running at compara-
tively high rotative speed and piston speed as well, which is gen-
erally considered to be one of the conditions which contribute
to good economy. The result, however, is nothing unusual.
The conclusion cannot fairly be drawn from this test that such
a speed produces no advantage ; for there were other conditions
pertaining to the work, such as the pressure and vacuum, which
were unfavorable to economy.

ENGINE No.56

100-
80—
60-
40-
20-
0-

H.P. Head End

H.P. Crank End

100

80

60

-40

-20

- 0

L.P. Head End

L.P. Crank End

ENGINE No. 57.

Compound Condensing Engine.

H. P.

CYLINDER.

L. P.

CYLINDER.

Kind of engine .

Four valv<
1

28

5
2.6

.1844

1

Practica

3 (Corliss)
1
56
6
5
3.7

.7425
4.03

lly tight

Number of cylinders

Diameter of cylinder ins.
Diameter of piston rod ins.
Stroke of piston ft.
Clearance %

Horse-power constant for one Ib. in.e.p.
one revolution per minute . . .H.P.
Ratio of areas of cylinders ....
Condition of valves and pistons regard-
ing leakage

Data and Results of Feed - Water Test.

Character of steam

. . . Ordinary

Duration

... 5.0

hrs.

Weight of feed-water consumed

. . . 94,545.

Ibs.

Feed-water consumed per hour

. . . 18,909.

Ibs.

Pressure in steam pipe above atmosphere ....

. . . 133.00

Ibs.

Pressure in receiver above atmosphere . . . . .

. . . 13.60

Ibs.

Vacuum in condenser

... 25.20

ins.

Revolutions per minute

. . . 66.04

rev.

Mean effective pressure, H. P. cylinder . ...

. . . 52.27

Ibs.

Mean effective pressure, L. P. cylinder

. . . 14.37

Ibs.

Indicated horse-power, H. P. cylinder . . .

. . . '• 636.61

H.P.

Indicated horse-power, L. P. cylinder . . . . ."

. . . 704.64

H.P.

Indicated horse-power, whole engine

. . . 1341.25

H.P.

Feed-water consumed per I. H. P. per hour . . .

. . ., 14.10

Ibs.

Measurements Based on Sample Diagrams.

H.P.
CYLINDER.

L. P.
CYLINDER.

Initial pressure above atmosphere . . Ibs.

125.2

139

Corresponding steam-pipe and receiver

pressure Ibs.

133.0

13.1

Cut-off pressure above zero .... Ibs.

121.3

20.8

Release pressure above zero .... Ibs.

38.9

10.1

Mean effective pressure Ibs.

51.87

14.5

Back pressure at mid stroke above or

below atmosphere Ibs.

+16.3

-11.4

Proportion of stroke completed at cut-off

.294

.429

Steam accounted for at cut-off . . . Ibs.

982

11.22

Steam accounted for at release . . . Ibs.

10.34

11.57

Proportion of feed-water accounted for

at cut-off

.696

.796

Proportion of feed-water accounted for

at release

.733

.821

228 ENGINE TESTS.

Engine No. 57 is a cross compound with unjacketed horizon-
tal cylinders and a reheating receiver. The condenser is of
the siphon type, the water for which is supplied by an inde-
pendent steam pump which takes steam from the main pipe
and exhausts into the receiver. Steam is furnished by vertical
water-tube boilers in a slightly superheated condition. The
load was cotton machinery. The leakage tests showed that the
valves and pistons were all in excellent condition throughout,
excepting the exhaust valve at the crank end of the low-pres-
sure cylinder, which leaked a considerable amount.

A test was made of the steam consumed by the condenser
pump when exhausting into the condenser; and it was found
that it used, under these circumstances, 1,176 Ibs. per hour, or
.9 of a pound per I. H. P. per hour. When exhausting into
the receiver, as it did on the test, the consumption was consid-
erably greater ; but a large proportion of it was utilized by
increasing the power developed in the low-pressure cylinder.
It is estimated that .5 of a pound per I. H. P. per hour is
chargeable to the condenser pump when used as it was on the
main test. The effect of exhausting the pump into the receiver
in this way is indicated in the analysis of the diagrams, which
shows a considerably larger amount of steam accounted for
in the low-pressure cylinder than that shown in the H. P.
cylinder.

ENGINE No. 57

H.P. Crank End

—120
-100
-80

— 60

— 40
-20
- 0

L.P. Head End

— 15

- 10

— 5

— 0

— 5

- 10

L.P. Crank End

- 16

- 10

— 6

— 0
5

- 10

ENGINE No. 58,

Compound Condensing Engine.

H. P.
CYLINDER.

L. P.
CYLINDER.

Kind, of engine

ins.
ins.
ft.

%

H.P.

Four valv
1
26
5
4
4

.1269
1
Practically
tight

e (Corliss)
1
50
5.5
4
4.8

.4719
3.72
Practically
tight

Number of cylinders
Diameter of cylinder
Diameter of piston rod

Stroke of piston
Clearance

H. P. constant for one Ib. m. e. p., one
revolution per minute ....
Katio of areas of cylinders ....
Condition of valves and pistons regard-
ing leakage

Data and Results of Feed -Water Tests.

TEST LOAD.

A.

CONSTANT.

B.
VARIABLE.

Character of steam

Ordinary

Ordinary

Duration .......... hrs.

2.5

3.0

Weight of feed-water consumed . . Ibs.

34,040.0

34,239.0

Feed-water consumed per hour . . . Ibs.

13,616.0

11,413.0

Pressure in steam pipe above atmos. . Ibs.

136.2

128.9

Pressure in receiver above atmosphere Ibs.

16.8

12.8

Vacuum in condenser ins.

26.2

26.2

Revolutions per minute

78.0

78.0

Mean effective pressure, H. P. cylinder Ibs.

*47.38

Mean effective pressure, L. P. cylinder Ibs.

*15.24

Indicated horse-power, H. P. cylinder H.P.

*468.97

Indicated horse-power, L. P. cylinder H.P.

*560.19

Indicated horse-power, whole engine . H.P.

1,030.06

843.44

Feed-water consumed per I. H.P. per hr. Ibs.

13.21

13.53

Measurements based on Sample Diagrams, Test A.

H. P.
CYLINDER.

L. P.
CYLINDER.

Initial pressure above atmosphere . .
Corresponding steam-pipe and receiver
pressure ^ . . .
Cut-off pressure above aero- d^r*0. .•'
Release pressure above zero . . ...
Mean effective pressure . i

Ibs.

Ibs.
Ibs.
Ibs.
Ibs

131.9

136.0
120.7
37.9
47 85

18.2

1(5.7

OJEX) I*
O

15.17

Back pressure at mid stroke, above or
below atmosphere

Ibs

+ 21.2

— 12.8

Proportion of stroke completed at cut-off
Steam accounted for at cut-off . . .
Steam accounted for at release . .
Proportion of feed-water accounted for

Ibs.
Ibs.

.293
10.56
10.92

.8

.274

9.48
9.69

.718

Proportion of feed-water accounted for
at release . .

.826

.733

230

ENGINE No. 58. 231

Engine No. 58 is a cross compound with horizontal un-
jacketed cylinders and a reheating receiver. The condenser is
of the jet type with an independent steam driven air-pump, the
quantity of steam used by which was determined and allowed
for. The steam is taken from water-tube boilers, and at the
throttle valve was found to contain .2 of one per cent of mois-
ture. The load was an electric generator carried by the fly-
wheel shaft, and on Test " A " the current was consumed in a
water rheostat, while that of Test " B " was used by the motors
of an electric street railroad, and the load was variable. The
valves and pistons were in an unusually tight condition
throughout.

The weight of steam condensed in the reheater coil on
test "A" was 500 Ibs. per hour, or about .5 of a pound per
I. H. P. per hour; and this is included in the quantities given
in the tables^ In th^ diagrams which are appended for the
variable load test, the two extreme lines are reproduced which
were taken for a period covering ten consecutive revolutions.
During the wh^Le trial with variable load, the maximum varia-
tion of the load was shown by the extreme readings of the
ammeter. The highest was 1,456 amperes and the lowest 624.
The next highest readings were 1,300 amperes, and the next
lowest 669.

* These figures were determined from ten sets of diagrams, the average
horse-power developed by the whole engine being 1029.16. The average
horse-power used for working up the results (1030.6) was determined from the
average electrical readings, using the efficiency corresponding to the readings
when the ten sets were obtained. On the variable load test the horse-power
was determined from the electrical readings by using the average efficiency
found by independent tests made with a steady load, this load being the average
load of the main trial.

ENGINE No. 58a

120-

100
80-
60-
40-
20-
0-

H.P. Head End

H.P. Crank End

-120
—100

— 80

— 60

— 40

— 20

— 0

L.P. Head End

-20

- 15

- 10

- 6

- 0
— 6

- 10

L.P. Crank End

-20

— 15
-10

— 5

— 0

— 5

— 10

ENGINE No.58b

120-
100-
80-
60-
40-
20-
0-

H.P. Head End

H.P. Crank End

—120
-100

— 80

— 60
—40

— 20
- 0

L.P. Head End

20

15
10
- 5
0
5
10

L.P. Crank End

20
15
10
5
0
5
10

TRIPLE EXPANSION

235

ENGINE No. 59.

Triple Expansion Engine.

H.P.
CYLINDER.

TNT.
CYLINDER.

L. P.
CYLINDER.

Kind of engine

Four

valve (Co

rliss)

Number of cylinders

1

2

Diameter of cylinders ... . . ins.

20

34

36

Diameter of piston rod ins.

4|

41

Stroke of piston ft.

5

5

I 6
5

Clearance %

2.5

2.5

2.5

H. P. Constant for one Ib. in.e.p., one

rev. per minute II. P.

.0928

.2727

.3017 each

Ratio of areas of cylinders ....

1

2.94

6.5 twc

Condition of valves and pistons regard-

Consid.

Practic'ly

Practic'ly

ing leakage

leakage

tight

tight

Data and Results of Feed -Water Test.

Character of steam

Duration

Wei giit of feed-water consumed

Feed-water consumed per hour

Pressure in steam pipe above atmosphere

Pressure in first receiver above atmosphere

Pressure in second receiver above atmosphere

Vacuum in condensers

Revolutions per minute

Mean effective pressure, H. P. cylinder

Mean effective pressure, intermediate cylinder . . .

Mean effective pressure, L. P. cylinder . .

Indicated horse-power, H. P. cylinder ,

Indicated horse-power, intermediate cylinder ..... (

Indicated horse-power, L. P. cylinder

Indicated horse-power, whole engine . ,

Feed-water consumed per I. H. P. per hour

Measurements Based on Sample Diagrams.

. Superheated 39°
10.375 hrs.
131,461
. 12,670.9
151
33
4

'. 27

65.24

59.59

13.19

10.19
360.9
234.7
401.2
996.8

12.71

Ibs.
Ibs.
Ibs.
Ibs.
Ibs.
ins.

Ibs.
Ibs.

H.P.
H.P.
H.P.
H.P.

Ibs.

..

H.P.
CYLINDER.

INT.
CYLINDER.

L. P.
CYLINDER.

Initial pressure above atmosphere . . Ibs.

142.

32.9

4.1

Corresp. steam-pipe pressure . . . Ibs.

152.

Cut-off pressure above zero .... Ibs.

145.2

38.7

16

Release pressure above zero .... Ibs.

53.

17.4

6.7

Mean effective pressure . . . . Ibs.

60.56

13.22

10.16

Back pressure at mid stroke above or

below atmosphere Ibs.

+32.6

+4.8

-12.5

Proportion of stroke completed at cut-off

.346

.406

.357

Steam accounted for at cut-off . . . Ibs.

9.81

9.53

8.39

Steam accounted for at release . . . Ibs.

10.42

10.45

9.95

Proportion of feed-water accounted for

at cut-off ....

.773

.741

.66

Proportion of feed-water accounted for

at release

.82

.822

.783

238 ENGINE TESTS.

Engine No. 59 is a horizontal four-cylinder engine, arranged
in the manner of a pair of tandem compound engines. The
cylinders nearest the beds are the low-pressure cylinders, of
which there are two. The high-pressure cylinder is in front
of one of the low-pressure cylinders, and the intermediate
cylinder in front of the other. The cylinders are jacketed on
the system which allows the steam which is supplied to the
cylinder to first pass through the jacket space, each jacket thus
being filled with steam having the initial pressure of supply.
The jackets are drained into receivers, and these are provided
with pumps operated by the engine. They discharge the
water into reheaters placed in the flue of the boilers. The
steam which is formed in the reheaters is supplied to the re-
ceiver between the intermediate and the low-pressure cylinders.
This receiver is provided with a coil of live steam pipe pre-
senting 33 square feet of exterior surface. The total quantity
of water condensed in the jackets and withdrawn from them
amounted to 691 Ibs. per hour, or about 5 % of the total quan-
tity of steam supplied to the engine. About one-half of this
was re-evaporated in the re heater and utilized in the low-
pressure cylinders. The condensers, of which there are two,
are of the jet type, and operated by direct connected air-pumps.
Steam is supplied from vertical tubular boilers, and on the test
it was superheated 39° at a point near the boilers. With the
exception of the high-pressure piston, which leaked quite badly,
the valves and pistons were all in a practically tight condition.

The load on the engine consisted of cotton machinery. The
loss of steam which, referring to the analysis of the diagrams,
took place between the intermediate cylinder and the low-pres-
sure cylinders is noticeable in view of the arrangements made
to reheat the steam in the receiver, and augment the supply
by means of the jacket-water re-evaporated in the flue heaters.
It shows the powerful action of cylinder condensation, and the
necessity of employing more efficient means for overcoming
the loss.

ENGINE No. 59

H.P. Head End

140-
120-
100-
80-
60-
40-
20-
0-

-140
120
100

- 80

- 60
-40

20

- 0

H.P. Crank End

Intm Head End

40-,
30-
20-
10-

o-

Intm Crank End

40
30
20
10
0

LNGINE No. 59

R.H.L.P. Head End

- 0

- 6

- 10

-15

R.H.L.P. Crank End

0-

6—
10-
15-

L.H.L.P. Head End

5-
0-
6-
10-
15-

L.H.L.P. Crank End

- 5

- 0

- 5
-10
-15

ENGINE No. 60.

Triple Expansion Engine.

H. P.
CYL.

INT. CYL.

L. P.
CYL.

Kind of engine .-..,.
Number of cylinders * .

Four

1
28
two 4
5
1.4
1
Fairly
tight

valve (Co
1
48
two 4
5
1.5
2.98
Fairly
tight

rliss)
1
74
two 4
5
.8
7.11
Fairly
tight

Diameter of cylinder ins.
Diameter of piston rod . ins.
Stroke of piston . ft.

Clearance %

Ratio of areas of cylinders
Condition of valves and pistons regarding
leakage

Data and Results of Feed- Water Test.
Character of steam . . . , . ... . •." . . .
Duration . . . . . ... . , . . . . .

Weight of feed-water consumed

Feed-water consumed per hour

Pressure in steam pipe above atmosphere

Pressure in first receiver above atmosphere

Pressure in second receiver above atmosphere

Vacuum in condenser .... . .

Revolutions per minute

Mean effective pressure, H. P. cylinder

Mean effective pressure, intermediate cylinder

Mean effective pressure, L. P. cylinder . . ... . . .

Indicated horse-power, H. P. cylinder ........

Indicated horse-power, intermediate cylinder . . .
Indicated horse-power, L. P. cylinder . . . . . . . .

Indicated horse-power, whole engine

Feed -water consumed per I. H. P. per hour . . ., .

Measurements based on Sample Diagrams.

Ordinary

72.0

hrs.

518,811.0

Ibs.

7,205.7

Ibs.

125.6

Ibs.

30.3

Ibs.

IKo

25.3

IDS.

ins.

20.99

rev.

49.85

Ibs.

15.4

Ibs.

7.57

Ibs.

191.3

H.P.

176.04

H.P.

206.39

H.P.

573.73

H.P.

12.55

Ibs.

H.P.
CYL.

INT.
CYL.

L. P.
CYL.

Initial pressure above atmosphere . . . Ibs.
Corresponding steam-pipe and receiver
pressure Ibs.
Cut-off pressure above zero . . . . . Ibs.
Release pressure above zero ..... Ibs.
Mean effective pressure Ibs

124.3

129.7
134.1
44.7

50 07

30.4

30.1
30.3
14.3
15 41

0.2

1.0
11.5

5.8
7 59

Back pressure at mid stroke, above or be-
low atmosphere Ibs.
Proportion of stroke completed at cut-off .
Steam accounted for at cut-off .... Ibs.
Steam accounted for at release .... Ibs.
Proportion of feed-water accounted for at
cut-off

+29.4
.338
9.48
9.96

.756

0.0
.362
9.53

9.97

.759

-11.9
.479
9.45
9.91

.753

Proportion of feed-water accounted for at
release ....

.793

.794

.789

241

242 ENGINE TESTS.

Engine No. 60 is a vertical triple expansion pumping-engine
with jacketed cylinders and two reheaters. Only the barrels
of the cylinders are jacketed, the heads being unjacketed, ex-
cept so far as the valve chests, which are located in the heads,
furnish a substitute. The jacket of the low-pressure cylinder
is supplied with steam at a reduced pressure. The remaining
jackets and the reheaters are supplied with boiler steam. The
engine is furnished with steam from horizontal return tubular
boilers, and at a point near the throttle valve the percentage of
moisture was found to be .3 %. There was no undue leakage
of the valves and pistons, but they were not in a perfectly tight
condition. The load of each cylinder is that of a direct-acting
pump, the diameter of each plunger being 36, " and the total
head, expressed in pounds, 53.4 Ibs. per square inch. The
jackets consumed 955 Ibs. of steam per hour, which is 12.7 % of
total used by the engine ; and this is included in the quantities
given in the tables. When the engine was at rest, the jackets
consumed 163.5 Ibs. per hour, being the loss due to radiation.

The analysis of the diagrams in this test shows a remarkably
close agreement between the steam accounted for by the indi-
cator in the various cylinders. There is a variation of less than
1 °f0 between the quantities shown at the cut-off in the three
cylinders, and a similarly close agreement in the three quanti-
ties shown at the release.

120-
100
80-
GO-
40-
20-
0-

ENGINENo. 60

H.P.Top

H.P Bottom

r!20
100
-80
-60
^40
-20
0

Intl^Top

-30

-20

10

- 0

-30
-20
-10

- o

ENGINE No. 6O

L.P. Top

o-

4-
8-
12-

L.P. Bottom

r— 0

-4
- 0
-12

SUMMARY OF FEED -WATER TESTS.

245

(0
0)

k.

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4-»

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246

ENGINE TESTS.

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SUMMARY OF FEED -WATER TESTS.

247

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248

ENGINE TESTS.

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REVIEW OF FEED -WATER TESTS.

249

REVIEW OF FEED -WATER TESTS.

IT could hardly be expected that conclusive information upon
the subjects which are of most interest in connection with the
operation of steam engines could be obtained from a large num-
ber of tests made on engines of various sizes, running under
different conditions of service, and located in plants which are
not always best adapted for experimental purposes or research,
like the tests under consideration. Such tests, however, cannot
but bring out some points on these subjects which are of consid-
erable practical value, if for no other reason than that the tests
were, in the main, conducted under those very circumstances of
practical operation which alone could give results of that nature.

The tests furnish information in regard to cylinder condensa-
tion, leakage of valves and pistons, the effect of pressure and
speed, the economy of condensing and superheating, the relative
economy of simple, compound, and triple expansion engines, the
effect of steam jacketting and reheating, the effect of different
ratios of cylinder areas in compound engines, and some miscel-
laneous questions ; and these are discussed in the order named.

I. CYLINDER CONDENSATION AND LEAKAGE.

Cylinder condensation and leakage is that part of the feed-
water consumption which is not accounted for by the indicator
diagram. It is necessary to put these two losses in one class^
There is no way of separating them either absolutely or ap-
proximately. The only practicable thing to do is to test the
valves and pistons for leakage with the engine at rest ; and if
under these conditions they prove to be tight, it is fair to as-
sume that the leakage under conditions of running is practically
nothing, and the part not accounted for by the diagram is
wholly or substantially cylinder condensation. If a similar
engine, working under similar conditions, is found by such tests

251

252

ENGINE TESTS.

to leak, and then a comparison is made between the loss in the
tight engine and that in the leaking engine, an inference can be
drawn as to the extent of the leakage and how much the loss
amounts to in percentage of the whole consumption. Practi-
cally, it may be said that it is unnecessary to know the absolute
amount of cylinder condensation, for it is seldom that an engine
is found in an absolutely tight condition ; and, after all, the im-
portant thing to know is what the cylinder condensation and
leakage amount to when the engine is in ordinarily good work-
ing condition. These tests furnish satisfactory evidence on this
point, especially those made on simple engines. Selection may
properly be made from the list of simple engines, those of the
larger sizes of the four-valve type, using ordinary steam, taking
those which are tight or leaking only a small amount ; namely,
those numbered 1, 2, 3, 5, 6, 7, 17, 18, 20, 22, 25, 28, 29, 30,
and 31. These are tabulated as follows, being arranged in the
order of the point of cut-off : —

No. OF
ENGINE.

CUT-OFF.

PROPORTION
OF FEED-
WATER
ACCOUNTED

FOR AT

CUT-OFF.

CYLINDER
CONDENSA-
TION AND
LEAKAGE.

31 A

.041

.382

.618

31 C

.084

.509

.491

18 B

.111

.668

.332

31 D

.121

.588

.412

20 A

.119

.615

.385

3A.

.138

.654

.346

30

.139

.645

.355

3B

.160

.695

.305

22

.172

.669

.331

31 C

.178

.709

.291

18 A

.188

.725

.275

29

.194

679

.321

20 B

.222

.722

.278

31 F

.231

.745

.255

7

.237

.750

.250

25

.243

.737

.263

6

.252

.757

.243

17 A

.264

.770

.230

28

.271

.781

.219

5

.303

.784

.216

2

.315

.817

.183

31 B

.323

.796

.204

1 A

.367

.840

.160

1 B

.375

.839

.161

17 B

.385

.820

.180

REVIEW OF FEED -WATER TESTS. 253

These proportions of cylinder condensation and leakage can
better be examined by referring to the accompanying chart on
which they are plotted, ordinates or verticals representing per-
centages of cut-off, and abscissae or horizontals, percentages of
condensation and leakage. The curved line drawn through
them represents the mean curve of condensation and leakage
deduced from these results. It clearly shows that the percent-
age rapidly increases as the point of cut-off becomes earlier,
and at the very earliest cut-off the condensation and leakage
bears a very large proportion to the total consumption of
steam.

The best series of tests on this subject, using the same
engine, are those made on Engine No. 31, which was a pair of
Corliss non-condensing engines having cylinders 16 in. diameter
and 42 in. stroke. This engine was practically tight, and the
percentages of condensation (and leakage) over a range of cut-
off from 4% to 32% was from 62% down to 20%.

That leakage has an important effect upon the economy of
an engine is well shown by a comparison of the results obtained
from engines which leaked excessively with those shown on
the chart. For example, in Engine No. 19, which is of the
single-valve type showing considerable leakage compared with
Corliss engines, the proportion of steam accounted for is .706
at 30% cut-off, giving condensation and leakage of 29.4%.
The condensation and leakage shown on the average curve of
the chart at that cut-off is about 20%, so that the difference
between 20 and 29.4 must be due in a laige degree to leakage.
In Engine No. 26 a test with a leaking exhaust valve showed
condensation and leakage of 30.8%. When the valve had been
repaired and made tight, the condensation and leakage dropped
down to 25.5%, the difference being due almost entirely to a
reduction in leakage. The saving in actual feed-water con-
sumption was about 10%.

In the compound engine tests which can be compared for the
purpose of studying cylinder condensation, the range of cut-
off in the high-pressure cylinder is hardly sufficient to serve
as a basis for satisfactory conclusions. The tests which can be

age of Condensation and Leakage

3 CO ^ 01 05 -J
) O O O O C

o
\

\

C

ONE

'ENS

Chart
ATION J

of

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LEA

KAGE

\

Tig

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r Fa

rly '

for
right Sin-

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Sngi

nes

\

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ry S

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atu rated

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m

\

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0

V

0

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0 ^

0

^

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^^

o

i

Percent

0 £

^

^-^

o7

o

— ' —

•

10

15 20 25

Percentage of Cut off

30

35

40

45

REVIEW OF FEED-WATER TESTS.

255

fairly compared for this purpose are those numbered 32, 34, 36,
49, 53, 55, 56, and 5 8 A. The range of cut-off in the high-
pressure cylinder is from .238 to .331, and the range of steam
accounted for at cutoff in the same cylinder is from .717 to
.866. These are tabulated below:

PROPORTION OF

NO. OF

ENGINE.

CUT-OFF,
H. P. CYL.

FEED-WATER
ACCOUNTED FOR
AT CUT-OFF,

H. P. CYL.

32

.305

.774

36

.295

.767

49

.330

.866

53

.238

.717

55

.326

.817

56

.331

.813

58 A

.293

.800

Average,

.303

.793

The average cylinder condensation and leakage in these
cases is 100-79.3 = 20.7%, and the average cut-off in the high-
pressure cylinder is .303. If these be compared with the
curve of condensation and leakage given on the chart for the
simple engines, it will be seen that this average falls closely
upon that curve. The point on the curve for 30% cut-off is
20.5%. The engines selected are those in which the high-pres-
sure cylinder is unjacketed, or of the class in which the jacket
space forms a thoroughfare through which steam is supplied
to the chest. It may be inferred from the close agreement be-
tween the average of these tests and the indications of simple
engines in the matter, that the curve of condensation and leak-
age for simple engines applies also to the high-pressure cylinder
of compound engines where these are unjacketed, and where
the valves and pistons are fairly tight.

Condensation and leakage in the low-pressure cylinder of the
compound engines reported above is affected to a considerable
extent by the conditions regarding jacketing and reheating,
Where there is neither jacketing nor reheating, the conden-

256

ENGINE TESTS.

sation and leakage is much greater in the low-pressure cylinder
than in the H. P. cylinder. For example, reference may be made
to Engines No. 32, 36, 46A, 47A, 48B, 52D, and 53, in which
the proportions of cylinder condensation and leakage are as
follows :

CONDENSATION

CONDENSATION

No. OF

AND LEAKAGE

AND LEAKAGE

ENGINE.

CUT-OFF

CUT-OFF,

H. P. CYL.

L. P. CYL.

32

.226

.28

36

.233

.36

46 A

.194

.29

47 A

.212

.32

48 B

.144

.26

52 D

.266

.35

53

.283

.40

Average,

.222

.323

The average of these shows 10% more condensation and
leakage in the L. P. cylinder than in the H. P. cylinder.

That leakage in itself produces an important effect in com-
pound engines is exhibited in the case of one engine reported,
that of No. 38, where the feed-water consumption per I. H. P.
per hour is 19.36 Ibs. The leakage here was in the low-pres-
sure piston ; and although the cylinders of the engine were jack-
eted, and the receiver also jacketed, the condensation and
leakage at cut>off in the H. P. cylinder was 32.5% against
17.5% by the simple-engine curve, and 57.0% at cut-off in the
L. P. cylinder; the increase between the two cylinders being
24.5%.

If we may judge from indications of one test, that of Engine
No. 26, the effect of leakage upon the consumption of steam
and economy of the engine may be exceedingly marked, and at
the same time have so little influence upon the lines of the
diagram that it may be scarcely noticeable. In this instance,
the form and position of the expansion line with reference to a
hyperbolic curve drawn through the cut-off point of the diagram
is so nearly the same that careful measurements would hardly

REVIEW OF FEED -WATER TESTS. 257

distinguish a difference, although in one case the exhaust
valve leaked no less than 10%. Practically the same effect, or
rather want of effect, has been noticed in one other case where
a broken packing-ring in a piston caused a leakage which
amounted to a still larger quantity. A close examination of
the expansion line of the diagrams, before and after, failed to
reveal any clearly denned difference. This is Engine No. 78.
In a case like that of the compound Engine No. 38, it cannot
be inferred from this that the influence of excessive leakage
could not be revealed by a study of the indicator diagrams.
Here it did produce a marked effect in the distribution of the
load between the cylinders, cutting down the power developed
in the L. P. cylinder, and increasing it to a corresponding ex-
tent in the H. P. cylinder. At the same time, it caused a
noticeable " drop " in pressure at the high-pressure release.

In studying the effect of cylinder condensation and leakage,
and the extent of the loss which it produces, the quantity
shown at the cut-off point of the diagram is selected in prefer-
ence to that shown at the release, in the belief that at the cut-
off point the full extent of the loss is the more truthfully
indicated. If the steam accounted for at both points is identi-
cal, the loss is the same at one point as at the other, and it does
not matter which point is selected. If the quantity accounted
for is larger at the release than it is at the cut-off, which owing
to re-evaporation during expansion frequently occurs, the appar-
ent loss due to condensation and leakage is less at the release
than it is at the cut-off. Sometimes there is as much as 10 per
cent less apparent condensation and leakage at the release
than at the cut-off. In cases like this the release percentage
does not show the full extent of loss, because the work recov-
ered on account of re-evaporation is in no sense proportional to
the increase in the steam accounted for at that point. Neither
does the loss at cut-off in such cases represent the true loss,
and the reason is the same ; but the loss at cut-off furnishes a
closer indication of the true loss than the loss at release, and
a better basis for the study of the question of cylinder conden-
sation.

258 ENGINE TESTS.

It will be noticed in the table giving the quantities upon
which the chart of cylinder condensation and leakage is based,
that no distinction is made between engines which are condens-
ing and those running non-condensing. It is probable that the
transfer of heat from the steam to the metal of the cylinder,
under the action of the comparatively low temperature of the
condenser, is different from that which occurs in the non-con-
densing engine ; and if a suitable investigation were made, this
difference would appear in the percentage of cylinder conden-
sation. Whatever this difference may be, it is not sufficiently
marked to be noticeable in the tests referred to in the chart;
and consequently the results are used indiscriminately, whether
the engines are condensing or non-condensing.

II. EFFECT OF PRESSURE ON THE ECONOMY.

Other things being the same, it is a well recognized princi-
ple in steam-engineering that the higher the pressure the more
economical the consumption of steam. But circumstances
attending its use are not always the same ; and consequently,
in examining the results obtained from different engines, such
as those here reported, it does not follow that in any individ-
ual case where the pressure is highest the economy is necessarily
the greatest. For example, two tests are reported on Engine
No. 18, which show practically the same economy as measured
by the feed-water consumed per I. H. P. per hour ; yet the
pressure in one case is 84 Ibs., and in the other case 59 Ibs. It
is evident that the difference in the cut-off which accompanied
the change of pressure exerted such an influence that the
benefit which might have been derived from a higher pressure
was counterbalanced.

There are two instances among the simple engines which
may be examined to show the importance due to increased
pressure. Test No. 1 A and test No. 2 is one of these in-
stances. Here an increase of the pressure from 72.3 Ibs. to
101 Ibs., accompanied by a slight shortening of the cui>off, had
a marked effect in improving the economy, the consumption of

REVIEW OF FEED -WATER TESTS. 259

feed-water being reduced from 27.8 Ibs. to 25.8 Ibs. Another
comparison may be made between test No. 7 and test No.
31 F. Here, with the same cut-off, an increase of pressure
from 80.5 Ibs. to 98.6 Ibs. was evidently the principal cause of
a reduction in the consumption from 29.03 Ibs. per I. H. P. per
hour to 25.31 Ibs.

In the list of the compound engines, there are two tests
which can be compared for this purpose, — those numbered 32
and 36. In No. 32, with a pressure of 94.8 Ibs., and the cut-
off in the high pressure cylinder .305, the feed-water consump-
tion is 16.28 Ibs. per I. H. P. per hour. In test No. 36, with
126.8 Ibs. pressure, and the cut-off at .295, or practically the
same as in the other case, the consumption is reduced to
14.05 Ibs.

That an increased pressure in the same engine is advanta-
geous under some circumstances, is clearly shown by test 48 A
and 48 C. In the latter the pressure was 100.2 Ibs., and the
consumption of feed-water 15.08 Ibs., while in the former the
pressure was 125,9 Ibs., and with practically the same load, the
consumption was 14.12 Ibs. In this case the benefit due to
the increase of pressure was largely enhanced by the increased
expansion obtained, the cut-off in the H. P. cylinder dropping
from .432 to .294.

III. EFFECT OF SPEED UPON ECONOMY.

The speeds, expressed in revolutions per minute, vary in
these tests from a minimum of 21 to a maximum of 356.7.
With such a wide range, there is reason for expecting informa-
tion as to the economy to be derived from increasing the
rotative speed, but the tests furnish no conclusive evidence on
this subject. The high-speed engines are all, or nearly all, of a
different class from the low-speed ones, and the nature of the
design and construction is such that certain features which are
necessary for the highest economy are sacrificed in order to
obtain the desired increase of speed. Many of the high-speed
engines have a single valve which performs all the functions of
the four valves in a slow-speed engine. The result is that

260 ENGINE TESTS.

these functions are not so perfectly performed in the engines
which run at high speed, and there is a loss of economy.
Furthermore, the valves in the high-speed engines are generally
of some balanced type ; and valves of this kind are not so well
adapted to tight construction, and do not maintain so tight a
condition as those of the four valves in slow-speed engines.
Again, the high-speed engines usually require larger clearance
spaces in the cylinders than those of the slow-speed class. For
these various reasons, the high-speed engine is handicapped at
the outset with conditions which are unfavorable to economy ;
and if the effect of the high speed is advantageous, the
advantage must be so great as to overcome the losses noted if it
is to show in favor of the high-speed engine when it is sub-
jected to a test. An examination of the tests reported, taking
those engines which are run at the highest speeds, shows, that
in every case they are less economical than the slow-speed
engines, and in every case the reason appears in one or more of
the points mentioned. There is a further reason for the com-
paratively low economy of the high-speed engines reported, in
the fact that in almost all cases the engines given are of com-
paratively small size ; and this, no doubt, has an important
influence in making the engine less economical than it would
otherwise be.

There is one case given where a Corliss engine was run at a
speed of one hundred and twenty revolutions per minute, — that
of Engine No. 56 ; and this may be compared with the other
Corliss engines running a lower speed. The comparison, how-
ever, is not a very satisfactory one ; because the valves and
pistons were not in the best condition in regard to leakage, and
the boiler pressure was rather lower than that obtained on other
engines with which it could be compared. Looking at the
proportion of steam accounted for by the indicator, which is
.813, there is nothing in this indication to show any marked
improvement due to the high rotative speed, if such existed.

REVIEW OF FEED -WATER

IV. ECONOMY OF CONDENSING.

It is held, in the popular mind, that the economy of con-
densing is, in round numbers, 25%. This percentage usually
relates to simple engines, and it refers to the economy as meas-
ured by the difference in the coal consumption produced by
a condenser. The evidence of some of the tests here given
shows that this belief is not well founded, unless it be in
special cases. The economy due to condensing ought to be
reckoned on the basis of coal consumption, and not alone on
the basis of feed- water consumption ; because a non-condensing
engine is usually accompanied by a feed- water heater, and some
of the loss of economy produced by running non-condensing is
made up by the saving of coal due to warming the feed-water.
If the feed-water is heated by the exhaust steam of the non-con-
densing engine from a temperature of 100°, which is that of the
ordinary hot well, to a temperature of 210°, the non-condensing
engine can be credited with about 11% less coal consumption.
This matter should properly be taken into account when con-
sidering the economy produced by a condenser.

In the list of simple engines, a number of comparisons are
made on the same engine when carrying the same load, one
test being made with the engine condensing and the other
non-condensing. In the case of Engine No. 10, where such a
comparison was made, the feed- water consumed when running
non-condensing was 25.64 Ibs. per I. H. P. per hour, and when
running condensing, 20.51 Ibs., the difference being 5.13 Ibs.,
or 20% of the larger quantity. In Engine No. 17, which
was tried in the same manner, the consumption running non-
condensing was 28.93 Ibs., and condensing, 22.08 Ibs., the
difference being 6.85, or 24% of the larger quantity. In
Engine No. 20, a similar test was made ; and the consumption
in one case was 30.16 Ibs., and in the other 23 Ibs., the dif-
ference being 7.16 Ibs., or 24% of the larger quantity. The
average of these three comparisons gives a saving produced
by condensing of 22.3%. If we allow for the steam or power
used by an economical condenser, it wrill be seen that the net

262 ENGINE TESTS.

economy of condensing is, at best, not much over 20% ;
and this is on the basis of steam consumption. If, further-
more, we allow for the difference produced by heating the
feed- water to the extent mentioned above, the saving of fuel
would be reduced to about 11%. In some cases in practice
where these conditions exist, the difference in favor of con-
densing might be greater, owing to the evaporative economy
of the boilers being improved by reducing the work upon
them ; but all that could be fairly expected on the basis of
these three engines, other things being the same, would be not
much over 10%.

There is another method of looking at this subject ; and that
is, to compare the best performance of engines running con-
densing with the best results running non-condensing. The
best non-condensing result, in the list of simple engines using
ordinary steam, is that of Engine No. 31 F, working at about
100 Ibs. pressure at .231 cut-off, and developing 287.1 indi-
cated horse-power. This result is 25.39 Ibs. The best result
obtained from a condensing engine, using ordinary steam, is
that of No. 22, working at a pressure of 82.3 Ibs. at .172
cut-off, the engine developing 613.4 I. H. P. This is 18.49
Ibs. per I. H. P. per hour. Comparing these two figures, there
is a difference in favor of the condensing engine of 6.9 Ibs.,
or 27.2% of the larger quantity. Allowing for steam or
power used by the condensing apparatus, the net economy
in feed-water consumption is not, at best, over 25% ; and fur-
ther allowance for the gain due to heating the feed-water, as
estimated in the former case, would bring the coal-saving down
to about 17%. It appears, therefore, that the tests here given
on simple engines do not confirm the popular impression that
the saving produced by condensing is 25%.

The economy of condensing, as compared with non-con-
densing, depends to some extent on the type of air-pump and
condenser employed. There are four principal classes of
these : —

1. The jet condenser and direct-connected air-pump, which
uses power supplied by the main engine.

REVIEW OF FEED-WATER TEtfTS. 263

2. The siphon type of condenser, in which the water is sup-
plied by gravity, and no air-pump is required.

3. The siphon condenser, in which the water is supplied by
an independent pump.

4. The jet condenser, with air-pump driven by an indepen-
dent engine or other motor.

In all of these, with the exception of the second, the expen-
diture of power or the consumption of steam must be charged
against the saving due to condensing. Those that use steam
can be arranged to utilize a portion of that steam in cases
where the exhaust from the independent engine or pump is
carried through a feed-water heater, and the heat returned to
the boiler. In test No. 15, which was provided with a jet
condenser and directrconnected air-pump, the amount of power
used by the air-pump was found to be 1.8% of the working
power of the engine. In Engine No. 57, which was pro-
vided with a siphon condenser supplied with water by an
independent pump, the quantity of steam used by the pump,
when exhausting into the condenser, was 6.7% of the total
consumption of steam by the engine. In Engine No. 19,
which was provided with a jet condenser operated by an in-
dependent steam-driven air-pump, the consumption of steam
by the pump when exhausting into the air was 13% of the
total quantity used by the engine. In Engine No. 20, which
was fitted with a similar condenser, the quantity of steam
used by the air-pump when exhausting into the condenser
was over 13% of the total quantity. When an independent
steam-driven air-pump is used, and the heat of the exhaust
steam is returned to the boilers so far as possible by heating
the feed-water, it is probable that from one-half to two-thirds
of the steam is saved ; and in a case where the air-pump uses
12% of the entire quantity, the actual loss of coal due
to the air-pump would be not over 4 or 5%. From these
considerations it appears that in cases where an air-pump
or other condenser pump is required, the percentage to be
charged to the condenser on this account is, in the best in-
stances, about 2% ; and in cases where the exhaust steam

264 ENGINE TESTS.

from the motor is not properly utilized, it may be so great
as to largely offset the economy otherwise resulting from the
use of the condenser.

The tests furnish some data as to the economy produced by
a condenser in compound engines. In Engine No. 33, with
practically the same load, the use of the condenser reduced
the consumption of steam per I. H. P. per hour from 22.53
Ibs. to 18.92 Ibs., or 16%. In Engine No. 45, the use of
the condenser, with a nearly "constant load, reduced the con-
sumption from 23.24 Ibs. to 16.07 Ibs., or 31%. A compari-
son may be made between Engines 41 and 42. The latter
(42 B), running non-condensing, used 25.2 Ibs. per I. H. P.
per hour ; and the former (41 B), running condensing, used
19.1 Ibs. The reduction due to condensing here is 24%.
Engine No. 46, which is run non-condensing, may be com-
pared with Engine No. 48, which is run condensing, making
allowance for the difference in the condition of the steam.
In this instance the condenser appears to have reduced the
feed- water consumption about 30%. In all these no account
is taken of the steam used by the condensing apparatus, the
percentages given being the gross savings. Throwing out En-
gine No. 33, w^hich may be regarded as of special design, and
possibly not useful for general comparison, it appears that the
effect of the condenser on the compound engines is considerably
greater than in the case of the simple engines. It will be seen,
however, that the advantage of the condenser in compound
engines depends largely upon the boiler pressure ; and a com-
parison made on an engine like No. 41, which is running at 130
Ibs., would show very differently from what it would in an en-
gine like No. 54, for example, which is run at 167 Ibs. The
effect of the vacuum on the low-pressure cylinder is much more
telling when the boiler pressure is low, and less work is done
in the high-pressure cylinder, than it is when the boiler pressure
is high.

At pressures ranging between 120 and 140 Ibs., it would
appear from these records that a 4-valve compound engine run-
ning non-condensing would use not over 21.5 Ibs. of feed- water

REVIEW OF FEED-WATER TESTS. 265

per I. H. P. per hour ; and a similar engine running condensing,
with the usual proportions of cylinders, would use not over
14 Ibs. The difference between the two is 7.5 Ibs., or about
35% in favor of the condensing engine. Allowing, say, 2%
for power used by a direct-connected air-pump, and making
further allowance, as in the case of the simple engines men-
tioned, for the effect of a feed-water heater, the net saving of
fuel in favor of the condensing engine is about 25%.

The effect on a pair of condensing engines produced by run-
ning one end of one cylinder non-condensing is shown in two
cases. In Engine No. 3 the effect was to increase the consump-
tion of feed-water from 21.11 Ibs. to 22.68 Ibs., or about 1%.
In Engine No. 9 the increased consumption amounted to
about 12%. The object of running an engine in this man-
ner is to utilize a portion of the steam for heating the feed-
water, or for other uses to which exhaust steam can be adapted.
If its use is confined to heating feed-water, and the amount is
110°, or that corresponding to the instances heretofore noted,
an advantage would be produced, provided the increased con-
sumption did not exceed 11%. If in these two engines the
exhaust steam from the single end were used for that pur-
pose, there would be a net gain corresponding to about 7%
in Engine No. 3, and a net loss corresponding to 1% in
Engine No. 9.

V. EFFECT OF SUPERHEATING.

The effect which superheating has upon the economy of an
engine is clearly shown in the case of Engine No. 1, where test
No. 1 C was made with the steam superheated 82°, and test
No. 1 B under practically the same conditions, except that the
steam was practically dry. This was a simple non-condens-
ing engine. The economy produced by the superheating was
sufficient to reduce the feed-water consumption from 29.34
Ibs., per I. H. P. per hour, to 26.83 Ibs., or 8.6% or about
1% for each 10° of superheating. This may be examined fur-
ther by comparing this and other simple engines which use
superheated steam with those using ordinary steam. The effect

266

ENGINE TESTS.

can best be studied by comparing the cylinder condensation and
leakage, in the case of the engines using superheated steam,
with the curve of condensation and leakage given on the chart
for simple engines using ordinary steam. For example, in the
case of test No. 1 C the cut-off is .392, the proportion of feed-
water accounted for at cut-off .947, and the cylinder conden-
sation and leakage 5.3%. On the curve for ordinary steam
referred to, the condensation and leakage at a cut-off of .392
is 16.7%. The difference between 5.3 and 16.7, which is
11.4%, represents the reduction in the condensation due to
the superheating, as determined by this method of comparison.
Pursuing the matter in the same way for the remaining
engines, we have the following table :

CYLINDER

No.

DEGREES

OF

SUPER-
HEATING.

CUT-OFF.

PROPOR-
TION OF
FEED-
WATER
ACCOUNTED

FOR AT

CUT-OFF.

PROPOR-
TION OF
CYLINDER
CONDENSA-
TION AND
LEAKAGE.

CONDENSA-
TION AND
LEAKAGE

DERIVED
FROM

CURVE FOR
ORDINARY

PROPOR-
TION RE-
DUCED BY
SUPER-
HEATING.

STEAM.

1 C

82

.392

.947

.053

.167

.114

4

25

.233

.766

.234

.255

.021

8 A

37

.247

.819

.181

.243

.062

8 B

37

.165

.747

.253

.334

.081

9 A

24

.18S

.820

.180

.307

.127

9B

24

.225

.836

.164

.261

.097

15

59

.281

.895

.105

.215

.110

Average,

41°

.087

From this comparison it appears that with steam superheated
41° (generally at a point near the boilers, and a considerable
distance from the engine), the proportion of condensation and
leakage was reduced an average of 8.7%. Assuming as a
criterion the relation between the actual saving in the case of
No. 1 Engine, and the reduced proportion of cylinder condensa-
tion, which was about .8, this reduction in the cylinder con-
densation corresponds to an actual saving of feed- water of 7%.
Assuming that if the engines had been supplied with ordinary

EEVIEW OF FEED- WATER TESTS. 267

steam, this steam would have contained 1% of moisture, cor-
responding in round numbers to, say, 20° of superheating,
the difference in the quality of the steam in the two cases,
expressed as superheating, is about 60°. According to this
calculation, therefore, the effect of the superheating is to re-
duce the feed-water consumption 7% for a superheating of
60°, or a trifle over 1% for each 10°; and this practically
corroborates the evidence furnished by the tests on Engine
No. 1.

The compound engine which shows the highest economy of
any in the list, is one which is supplied with superheated steam ;
and although this fact may be considered as one reason for
the high result, there were other conditions which were favor-
able, and the exact effect of the superheating is a matter of
conjecture.

Incidentally, it should be noted that superheating produces
a marked effect in the character of the expansion line of the
indicator diagram. In Engine No. 1 this is clearly revealed by
a comparison of the steam accounted for by the indicator at
cut-off and release. In test No. 1 B, where the engine was
running with ordinary steam, the proportion accounted for at
cut-off is .839, and that at release is .861, which is an increase
of .022. On the other hand, on test No. 1 C, where the steam
was superheated 82°, the proportion accounted for at cut-off
was .947, and at release .900, there being a reduction here
of .047. This change is evidently due to the reduced con-
densation produced by the superheating, and the consequent
reduction in the amount of re-evaporation during expansion.

VI. RELATIVE ECONOMY OF SIMPLE, COMPOUND AND TRIPLE
EXPANSION ENGINES.

In comparing the economy of a compound or other multiple
expansion engine with that of a simple engine, the question may
be raised, What should be the conditions of the comparison ?
One method of comparing the two would be to select those run-
ning under the same boiler pressure and quality of steam, and

268 ENGINE TESTS.

with similar provisions in regard to jacketing. This method
may be interesting and valuable for scientific research ; but for
practically showing the advantages of compound engines, it is of
little importance, because one of the principal objects in com-
pounding is to enable the economy due to large expansions and
high pressures to be obtained without the sacrifice which such
expansions produce when carried on during the single stage
which occurs in one cylinder. The nearest approach to a com-
parison of this kind, derived from the tests reported, is that of
compound Engine No. 32, which was made with a boiler pres-
sure of 94.8 Ibs. Here the engine was unjacketed, and no
provision was made for re-heating between the cylinders. If
we compare this with the very best result obtained from a
simple condensing engine, that of No. 22, there appears, even
under these circumstances, a marked difference in favor of the
compound engine. These figures are 18.49 for the simple
engine, and 16.28 for the compound; and the difference is 2.21
Ibs., or about 12%. Comparing this, again, with simple Engine
No. 28, which is running at 70 Ibs. pressure on a consumption
of 19.45 Ibs. of feed-water per I. H. P. per hour, the difference
is 3.17 Ibs., or 16.3%.

A fairly satisfactory comparison between compound engines
and simple engines, where no jacketing or re-heating is pro-
vided, can be made by using compound Engine No. 36. This
engine was jacketed ; but the jackets were not drained, and
consequently, under the circumstances, they were ineffective.
In this engine the consumption of feed-water was 14.05 Ibs.
per I. H. P. per hour when running at a pressure of 106.8 Ibs.
If we compare this with No. 28, simple engine, the difference
is 5.4 Ibs., or 27.8%.

A general comparison between the compound and simple
engines may be made without regard to the matter of pressure
or the use of jackets and re-heaters, and without regard to the
quality of the steam, omitting the three engines which have an
excessively high ratio of cylinder areas. The engines selected
are those of the Corliss or other 4-valve type. Such a compari-
son is made in the following tables.

REVIEW OF FEED- WATER TESTS.
Simple Condensing Engines.

269

NUMBER.

FEED-WATER CONSUMED
PER I. H. P. PER HOUR.

3 A

21.11

8 A

19.39

8 B

18.71

9 A

18.25

18 A

20.31

18 B

20.56

22

. 18.49

28

19.45

30

21.42

Average,

19.74

Compound Condensing Engines.

NUMBER.

FEED-WATER CONSUMED
PER I. H. P. PER HOUR.

32

16.28

34

13 28

36

14.05

37

13.37

43

13.26

48 A

14.12

48 B

14.01

48 C

15.08

49

14.18

50

13.28

53

15.78

55

13.27

56

14.60

57

14.10

58 A

13.21

Average,

14.12

The average of the results on the simple condensing engines
is 19.74 Ibs., and of those on the compound condensing engines,
14.12 Ibs. The difference is 5.62 Ibs., or 28.5% of the feed-
water consumption of the simple engines.

In the case of non-condensing compound engines of the
4-valve type, there is only one engine in this class, Engine No.

270 ENGINE TESTS.

46. Test No. 46 B on this engine gave a feed-water consump-
tion of 21.59 Ibs. This may be compared with Engine No. 2,
which was run non-condensing at a pressure of 101 Ibs., and
gave 25.8 Ibs. consumption. Here the economy due to the
compound engine is 4.21 Ibs., or 16.3%. This is rather unfav-
orable to the compound engine on account of the relatively
small difference in the boiler pressures.

Referring- to the single- valve engines running condensing,
comparison may be made between Engine No. 41 and Engine
No. 19. Engine No. 19, the simple engine, used 27.15 Ibs. per
I. H. P. per hour, and Engine No. 41 B, compound, used 19.1
Ibs., the difference being 8.05 Ibs., or an economy of 29.6%.
There are no single-valve engines of the non-condensing class
from which to make a fair comparison between the com-
pound and simple engines, owing to the great difference in the
sizes ; but the results obtained on engines of this kind, disre-
garding their size, are of the same kind as those already
discussed.

The results of the tests on the two triple expansion engines
which are given, show an average consumption of 12.63 Ibs.
of water per I. H. P. per hour. This is below the average of
14.12 Ibs. for the various compound condensing engines which
are tabulated, and it is below the result obtained from any
individual engine given in that table. It is better to the ex-
tent of 10%, compared with the average. This result is not,
however, so good as that obtained from the special com-
pound Engine No. 51, where the ratio of cylinder areas is
about the same as the ratio between the low-pressure cylinder
and the high-pressure cylinder of triple expansion engines.

VII. ECONOMY OF STEAM JACKETING AND RE-HEATING IN
COMPOUND ENGINES.

There are two compound engines given where the effect of
shutting off the steam from the jackets and re-heater tubes
was tested, these being No. 47 and No. 52. In each of these
cases, the difference in the feed-water consumption per I. H. P.

REVIEW OF FEED-WATER TESTS. 271

per hour was 2%. Both of these are cases where the ratio
of area of the two cylinders was unusually large, and the
re-heating surface in the receiver was also unusually large,
being sufficient to superheat the steam that passed into the
low-pressure cylinder. Whatever value jacketing and re-heating
may have in a compound engine, it may be reasonably expected
that it would show to the best advantage where the expansion
is carried to the greatest extent ; and consequently the condi-
tions of these two cases are as favorable to a good showing for
the jackets as they could be in most engines of the compound
type. It would appear then, that 2% is the most that can be
expected for the saving of steam due to jackets and re-heaters
in ordinary compound engines of the types referred to.

There are none of the tests of the other compound engines
which furnish much actual data on the subject ; but it may be
said that the superficial indications of the results of the tests
where the engines are jacketed, furnish little ground for the
belief that jacketing had much effect upon the economy. Take
the case of Engine No 58 A, which had no jackets, but which
was fitted with a re-heating receiver. The consumption of
feed- water was 13.21 Ibs. per I. H. P. per hour, and this is
lower than any result given where the engine was provided
with jackets. No doubt the unusually tight condition of the
valves and pistons in this case had a favorable effect; but if
jacketing is necessary for good economical results and the
advantage it produces is a marked one, its absence in Engine
No. 58 should have produced a much ^more noticeable effect.

Beyond the saving in steam consumption produced by jack-
ets, which in Engines No. 47 and 53 amounted to 2%, there
is a further saving in fuel which cannot be overlooked, which
may be obtained by returning the hot water condensed in the
jackets to the boilers. The temperature of this water is
ordinarily about 300°, and its quantity on the tests noted
was 7.7% in one case, and 11% in the other, averaging
9.3% for the two. If the temperature of the main supply
of feed- water is 100°, the return of this water to the boilers
would add about 19° to the temperature of the feed-water,

272 ENGINE TESTS.

and increase the efficiency of the boilers a little less than
2%. If the temperature of the main feed-water was at a
higher point, the effect of the heat returned from the jackets
would be correspondingly less. If we make this for an aver-
age case, l-J-%? we should have the combined economy of the
jackets due to both causes about 3£%.

There is one test of a compound engine which was made to
determine the effect of shutting off the steam from the re-
heater, in a case where the cylinders were unjacketed. This re-
lates to Engine No. 48. Test A was made with the re-heater
on, and test B with the re-heater off. The figures show that
the engine was the most economical in the latter case, the
difference between .11 of a pound or .7 of 1% ; so that in
this one instance it would seem that the use of the re-
heater produced a loss in steam consumption instead of a
gain. If allowance is made for the heat which could be re-
turned from the water of condensation to the boilers, the
advantage from this source would be nearly 1%, so that
there was a slight advantage in fuel economy due to the use
of the re-heater.

Whatever the actual economy due to jacketing or to re-
heating or to both, which from the evidence of these tests
appears to be rather small, there is no question but that the
action of the jacket and the re-heater produces a powerful in-
fluence on the steam in its passage through the cylinders. The
effect upon the indicator diagrams is very marked. The use
of these appliances makes the engine more powerful in view of
the fact that it increases the work done by the low-pressure
cylinder for a given amount performed by the high-pressure
cylinder. In Engine No. 47, the low-pressure cylinder de-
veloped 34 horse-power less than the high-pressure cylinder
when the jackets and re-heater were off, and 10 horse-power
more than the H. P. cylinder when the jackets were on. In
Engine No. 52, the low-pressure cylinder developed 24 horse-
power more than the H. P. cylinder when the jackets and re-
heater were off, and 92 horse- power more when the jackets
were on. In Engine No. 48, the low-pressure cylinder de-

REVIEW OF FEED-WATER TESTS. 273

veloped 56 horse-power less than the H. P. cylinder when the
re-heater was off, and 19 horse-power less when the re-heater
was on.

The effect of the jacketing and re-heating is also seen to
be very marked when comparison is made between the steam
accounted for in the two cylinders. In Engine No. 47, with
the jackets off, the steam accounted for in the L. P. cylinder
at cut-off is 10.8% less than in the H. P. cylinder; whereas
with the jackets on, the difference is only 1%. In Engine
No. 52, with jackets off, the steam accounted for in the L. P.
cylinder is 8.4% less than in the H. P. cylinder. When
the jackets were on, it was 12.9% more than in the H. P.
cylinder. In Engine No. 48, the steam accounted for in
the L. P. cylinder with the re-heater off, was 11.6% less
than that in the H. P. cylinder ; whereas, when the re-heater
was on, it was only 4.2% less. In Engine No. 55 the effect
of the re-heater on the diagrams is seen to be considerable,
from the fact that the steam accounted for in the L. P.
cylinder is 1.3% more than that accounted for in the H. P.
cylinder.

VIII. EFFECT OF RATIO OF CYLINDER AREAS IN
COMPOUND ENGINES.

In most of the compound engines given, where these are of
the Corliss or other 4-valve type, the ratio of cylinder areas is
between 3.5 and 4. Three cases are given, however, where
the ratio is about 7 to 1, these being Engines 47, 51, and 52.
The engines with the large ratio of cylinder area show more
economical results than the others. The difference is not so
noticeable in No. 52 as it is in Nos. 47 and 51. In both these
cases, however, the pressure is higher than it is in most of the
tests given with the lower ratios ; and this higher pressure fur-
nishes one reason for the better result. There is one case of a
pressure of 151 Ibs. in an engine having a low ratio with which
these may be compared, and that is Engine No. 55. This
engine gives a horse-power for 13.27 Ibs. of feed-water per

274 ENGINE TESTS.

hour. Engine No. 47 B gives 12.45 Ibs., while Engine No.
51 C, gives 11.89 Ibs. Taking the average of the last two,
which is 12.17, there is a difference between the two cases in
favor of the larger ratio of areas of 1.1 Ibs. or 8%. Engine
No. 55, as will be seen, does not give so well-formed diagrams,
there being considerable wiredrawing in the H. P. cylinder;
and the result obtained on this engine is not so good as it
would have been if these conditions had been better. Making
due allowance for this, however, and further allowance for the
fact that Engine No. 51 was supplied with slightly superheated
steam, there appears to be a noticeable advantage in the use of
the higher ratio of cylinder area for an engine running at 150
Ibs. pressure. It is a noteworthy fact that with the high ratio
of area, an excellent steam distribution, and a slight amount of
superheating, the most economical result given in the whole list
of tests is produced, — Engine No. 51 C producing a horse-
power for 11.89 Ibs. of feed- water per hour.

IX. MISCELLANEOUS.

The tests furnish some indication as to the loss of economy
produced by light loads, especially in non-condensing engines.
In Engine No. 16, which is a single-valve, single-acting engine
of the high-speed class, the consumption of steam per horse-
power per hour was increased from 32.6 Ibs. to 36.27 Ibs., by
reducing the horse-power developed from 44.8 H. P. to 25.7
H. P. In Engine No. 23, which is of the single-valve high-
speed class, the consumption increased from 30.63 Ibs. to 31.78
Ibs., corresponding to a reduction of load from 39.4 H. P. to
22.2 H. P. In Engine No. 31, which is of the Corliss type, the
consumption was fairly constant with a load varying from 222
H. P. to 342 H. P., but with lighter loads it rapidly fell off;
and with the load of the idle engine and shafting, which was 37
horse-power, the consumption rose to 73.63 Ibs. per I. H. P. per
hour. In Engine No. 42, which is a single-valve high-speed
compound, the consumption was increased from 25.2 Ibs. to
44.89 Ibs. by reducing the load from 152.5 H. P. to 45.6 H. P.

REVIEW OF FEED-WATER TESTS. 275

In Engine No. 54, which is a single-valve compound, the feed-
water consumption, was nearly constant for loads of 242.9 H. P.
and 187.5 H. P. ; but it was increased from 21.14 Ibs. to 24.99
Ibs. by dropping the load to 103.4 H. P. In Engine No. 41, a
single-valve compound condensing, the consumption was in-
creased from 19.1 Ibs. to 22.74 Ibs. by reducing the load from
196.8 H.P. to 90.5 H.P. In Engine No. 45, which is a double-
valve compound condensing, the consumption was increased
from 15.71 Ibs. to 17.22 Ibs. by reducing the load from 244.5
H. P. to 123.4 H. P.

Very little information of definite character is furnished by
the tests as to the effect of size of cylinder on economy. Most
of the smaller engines given are of the single-valve class, with
shaft governors, running at high speed; and although these
generally show less economy than the larger engines, it would
hardly be fair to attribute it to the smaller size of cylinder
when other differences of condition are known to be of much
importance. Two cases are given for Corliss engines which
seem to show that a considerable difference of size has no
appreciable effect. These are Engine No. 2, having a 28.5 "
x 59.5" non-condensing cylinder, and Engine No. 31, which
had 2-1 6 " x 42" cylinders. The former gave a horse-power for
25.8 Ibs. of feed-water per hour ; and the latter, when working
at about the same cut-off, for 25.9 Ibs. per hour, or practically
the same result. Cylinder condensation and leakage is 2.1%
greater in the case of the smaller engine ; and this fact fur-
nishes a slight indication that the smaller engine was the more
wasteful.

It needs but a glance at the results of the various tests to
show that the 4-valve engines are more economical as a type
than those having a less number of valves ; and this is true
whether they are simple or compound, and whether condensing
or non-condensing. The single-valve compound non-conden-
sing Engine No. 54, compared with the 4-valve compound
non-condensing Engine No. 46, shows a better result, some
2% ; but it will be observed that the former works under a
pressure of 165 Ibs., while the pressure in the latter case is 135.

276 ENGINE TESTS.

As the economy of non-condensing compound engines is greatly
affected by the boiler pressure, the single-valve engine in this
case has an undoubted advantage, which more than makes up
for the difference produced hy the valve. The superior econ-
omy of the 4-valve type is evidently due in part to the better
distribution of the steam in the cylinders, as revealed by more
perfectly formed diagrams ; and, in some cases to the tighter
condition of the valves and pistons.

One test is given that shows the loss in economy due to the
variable load produced in electric railway service. This is
Engine No. 58 B, which is a Corliss compound condensing
engine. Compared with test No. 58 A, which was made
with the same engine working under a steady load, the loss is
only 2.5%. On the test with the variable load, the average
power was 843.4 H. P., while that with the steady load was
1030.1 H. P. It is evident that the difference in economy
shown was caused to a considerable extent, if not wholly, by
the fact that in the variable load the engine is at times under-
loaded, and not working to its best economical advantage.
This was probably an unusually favorable showing for a varia-
ble load in the service mentioned, for the reason that the range
of variation was less than occurs in much work of this kind.
An examination of the indicator diagrams gives some idea of
the extent of the variation.

One method of reducing the loss of steam where compound
engines are used, is to exhaust the air-pump into the receiver
of the engine. This virtually converts the air-pump from a
simple engine to a compound engine. The effect of thus util-
izing the exhaust steam of the air-pump is seen in test No. 57.
The effect is shown by the large increase of the amount of
steam accounted for in the low-pressure cylinder, as compared
with that in the high-pressure cylinder. The increase is from
.696 to .80, or .104. In Engine No 55, which is of similar
type except in this particular, the increase is only .013 ; and in
Engine No. 58 A, also similar in type, there is a falling off of
.08. In Engine No. 57, the steam used by the air-pump when
exhausting into the condenser amounted to .9 of a pound per.

REVIEW OF FEED- WATER TESTS. 277

I. H. P. per hour, and when exhausting into the receiver it
was, of course, a much larger quantity; but in spite of this
the extra power produced by the use of the steam in the low-
pressure cylinder was such that the entire consumption of
the engine and condenser was only 14.1 Ibs. per I. H. P. per
hour.

One test on a compound engine is given, where the water
drained from jackets and receiver was pumped into a flue
heater, and the steam produced by its re-evaporation brought
back to the receiver and used in the low-pressure cylinder.
This is Engine No. 50. Under the circumstances of a compar-
atively low boiler pressure, which was 108.1 Ibs., the economi-
cal result obtained, which was 13.28 Ibs. per I. H. P. per hour,
must be considered excellent. The engine, however, was sup-
plied with superheated steam ; and this condition is, no doubt,
accountable, in some degree at least, for the result obtained.
It is doubtful whether the re-heating had any marked effect ;
because it appears that the steam accounted for in the L. P.
cylinder is .77 as against .889 in the H. P. cylinder, showing a
loss between the two of .119. If this is compared with Engine
No. 49, which is supplied with ordinary steam, and had no
re-heating feature, there is a difference between the two cylin-
ders of .106 ; so that there is no more loss in this case between
the cylinders than in Engine No. 50, which had the re-heating
system.

The evidence of the tests furnish some data upon the effect
of varying the receiver pressure in a compound engine, but
this data is not conclusive as applied to other engines. In the
case of Engine No. 51, three tests made with nearly the same
load and with a receiver pressure, ranging from 5.4 Ibs. above
the atmosphere to 12.9 Ibs., the cut-off in the low-pressure
cylinder being gradually shortened as the pressure increased,
showed a gradual reduction in the feed-water consumed per
I. H. P. per hour. With the lowest pressure, it was 12.29 Ibs.,
and with the highest, 11.89 Ibs. In Engines No. 47 and 52,
where similar tests were made with three different receiver
pressures, practically the same result is produced at the two

278 ENGINE TESTS.

extreme pressures. In one case, the intermediate pressure gave
a slight reduction, whereas in the other, the intermediate pres-
sure gave a slight increase in the consumption.

IN CONCLUSION.

A careful study of these tests should be of service to engi-
neers in designing new plants or re-organizing old ones, inas-
much as they show, within the limits covered, what designs
and practices should be avoided, and what conditions should be
observed in order to secure desired results in the best manner.

VALVE SETTING.

279

ENGINE No. 61.

Double valve, 6" x 14". Speed, 210 revolutions per minute.

This is an automatic cut-off engine with slide valves and
shaft governor. The main valve is of the box pattern, with
balance plates on the back face. Steam is admitted into the
interior of the box before it passes through the ports into the
cylinder. The cut-off valve rides on a seat inside, and is
operated by a separate eccentric, which is shifted by the action
of a shaft governor. The diagrams here given show the effect
of moving the eccentric which operates the main valve an
angular distance of 43° on the shaft. This represents a dis-
tance of 14-" on a shaft 4" in diameter. No. 61a was taken
before, and No. 615 after, the change.

ENGINENo. 61a

ENGINE No. 61b

281

ENGINE No. 62.

Four valve, 16"x48". Speed, 82 revolutions per minute.

This engine is of the 4-valve type, the steam valves being
slide valves, and the exhaust, Corliss valves. They are oper-
ated by separate eccentrics. Changes in the setting of the
valves consisted in moving the steam-valve eccentric ahead
2" measured on the circumference of the 8" shaft, moving the
exhaust eccentric ahead $", adjusting the tappet which operates
the steam valve so as to obtain earlier admission, and shorten-
ing the exhaust-valve rod two turns to obtain earlier release.
The diagrams were taken from the head end, No. 62 a before,
and No. 626 after, the change.

In connection with these changes feed-water tests were made
which showed a saving of 8 % on the steam used by the plant
of which this engine formed a part; the total power of the
plant being somewhat more than twice the power developed
by this engine.

ENGINE No. 62a

282

ENGINE No. 63.

Four valve (Corliss), 18" x 48". Speed, 57 revolutions per
minute.

This engine is of the ordinary Corliss type with single eccen-
tric. The changes in the valves consisted in moving the
eccentric forward -J- inch on a 10" shaft, and shortening the
steam-valve rod 4 turns, or 4 threads. The diagrams were
taken from the head end, No. 63# before, and No. 636 after,
the change.

ENGINE No.63a'

ENGINE No.63b

283

ENGINE No. 64.

Four valve (Corliss), 23" x 48". Speed, 51 revolutions per
minute.

The steam-valve rod was lengthened 6 turns, or 6 threads,
to reduce the lead. The diagrams are from the crank end,
No. 64a being taken before, and No. 646 after, the adjustment.

ENGINE No. 64a

ENGINE No. 64b

284

ENGINE No. 65.

Speed, 67 revolutions per

Four valve (Corliss), 14" x 36".
minute.

The eccentiic was moved forward f " on the 7" shaft. The
steam-valve rod was shortened 6 turns or 6 threads. The dia-
grams are from the head end, No. 65a being taken before, and
No. 656 after, the change.

ENGINE No. 65a

285

ENGINE No. 66.

Four valve (Corliss), 26" x 60". Speed, 51 revolutions per
minute.

The changes in the valve-setting consisted in moving the
eccentric forward-^" on the 12" shaft and shortening the ex-
haust-valve rod 2y turns, or 5 threads, so as to secure earlier
release. The diagrams are from the head end of the cylinder,
No. 66a being taken before, and No. 665 after, the change.

ENGINE No. 66a

286

ENGINE No. 67.

Single valve, 8" x 10". Speed, 326 revolutions per minute.

This engine is of the automatic cut-off type with shaft gov-
ernor, shifting eccentric, and balanced slide valve. These
diagrams show the effect of unequal adjustment of the lap of
the valve. The first set, 67 a and 676, was taken with the
engine loaded. The mean effective pressure at the head end
is 8 Ibs., and at the crank end, 32.4 Ibs. The second set, 61 c
and 67c?, was taken with a friction load. Here the mean effec-
tive pressure at the head end is a minus quantity, and at the
crank end a plus quantity. The third set, 670 and 67/, was
taken under the same conditions of load as the second, after
equalizing the lap. With this adjustment the mean effective
pressure at the head end was 1.9 Ibs., and at the crank end,
3.4 Ibs.

ENGINE No.67a

Head End

-30

20

— 10

0

ENGINE No. 67b

Crank End

-60
-50
-40
-30
-20
-10
- 0

287

ENGINE No. 67c

Head End

30

20

10

- O

ENGINE No. 67d

Crank End

70

60

50

40

30

20

-10

0

ENGINE No. 67e

Head End

30

20

10

0

ENGINE No. 67f

Crank End

-40
30
-20
-10
- 0

ENGINE No. 68.

Four valve, 13" x 36". Speed, 61 revolutions per minute.

This engine has double poppet valves for admission, and
slide valves for exhaust. The valves are operated by a train
of gears and cams. The adjustments consisted in moving for-
ward the cam which operates the steam valve so as to produce
earlier admission. The diagrams are taken from the head end,
No. 68# before, and 685 after, the changes.

ENGINE No. 68a

ENGINE No. 68b

289

ENGINE No. 69.

Four valve, 11" x 30". Speed, 80 revolutions per minute.

This engine has double-poppet admission valves, and slide
valves for exhaust ; all driven by a train of gears.

The steam- valve cam was moved forward 1" on its shaft, and
the exhaust cam £". The diagrams are taken from the crank
end, No. 69a before, and No. 696 after, the adjustments.

ENGINE No. 69a

J

290

ENGINE No. 70.

Four valve, 18" x 42". Speed, 55 revolutions per minute.

In this engine the steam valves are double poppet, and the
exhaust valves, slides. The mechanism is driven by means of
bevel gears. The adjustment of the valves consisted in moving
the driving-gear forward on the shaft two teeth. The total
number of teeth on this gear was 44. The diagrams are from
the head end, No. 70a being taken before, and No. 706 after,
the changes.

ENGINE No. 70a

ENGINE No. 7Ob

291

ENGINE No. 71.

Four valve, 14" x 35". Speed, 49 revolutions per minute.

This engine has two double-poppet steam valves, and slide
valves for the exhaust; all driven through a train of gears.
The changes consisted in moving the stem of the steam valve
in so as to clear the driving-cam, and setting the gear forward
on the shaft 2 teeth. The diagrams were taken from the head
end, No. 71# before, and No. 716 after, the adjustments.

ENGINENo. 71a

ENGINE No. 71b

292

ENGINE No. 72.

Four valve, 16" x 36". Speed, 72 revolutions per minute.

This engine has two double-poppet steam valves, and slide
valves for the exhaust. They are driven through a train of
gears.

The gear which drives the valves was changed, with a view
to securing compression of the exhaust steam up to the initial
pressure, being moved forward, thereby hastening the release
as well as the compression. This change was made with the
object of studying the effect of compression upon the actual
economy of the engine under conditions of practically the same
oad. So far as this test showed anything, under these condi-
tions, there was in reality a slight increase in the amount of
feed-water consumed per horse-power per hour, attending the
earlier compression. The diagrams were taken from the crank
end, No. 72a before, and No. 726 after, the change.

ENGINE No. 72a

ENGINE No. 72b

293

ENGINE No. 73.

Four valve, 26" x48". Speed, 50 revolutions per minute.

The steam valves in this engine are slide valves, and the
exhaust are Corliss valves.

The change here consisted in moving the driving-gear for
the steam valves one tooth ahead, the total number being 42,
and in shortening the exhaust rod so as to reduce the lap on
the exhaust valve. The diagrams were taken from the head
end, No. 73a before, and No. 736 after, the changes.

ENGINE No. 73a

ENGINE No. 73b

294

ENGINE No. 74.

Four valve, 18" x48". Speed, 64 revolutions per minute.

All the valves in this engine are slides driven by double ec-
centrics. The adjustments consisted in advancing the steam-
valve eccentric 1J-" on the 9" shaft, and the exhaust eccentric
% inch. The diagrams were taken from the head end, No.
74a before, and No. 746 after, the changes.

ENGINE No. 74a

ENGINE No. 74b

295

ENGINE No. 75.

Four valve (Corliss), 30" x 48." Speed, 80 revolutions per
minute. The setting of the valves was changed by the intro-
duction of a separate eccentric for driving the exhaust valves,
and the adjustment of this eccentric so as to obtain early
compression. With a single eccentric the engine operated
unsatisfactorily on account of the noisy action of the piston
and valves, there being decided and annoying sounds at each
end of the stroke, which could be distinctly heard by a
person standing at a distance of 20 feet from the cylinder.
When the additional eccentric had been applied and the valves
readjusted, the troublesome sounds so far disappeared that it
was necessary for the observer to hold his ear close to the
cylinder to be aware of any disturbance. The diagrams were
taken from the head end, and for ready comparison, they are
superimposed, the full line being taken with single eccentric
and the dotted line after changing to double eccentrics and re-
setting the valves.

ENGINE No. 75

296

ENGINE No. 76.

Four valve, 20" x 50." Speed, 64 revolutions per minute.

This engine has four slide valves, all operated by means of
a train of gears. The diagram here given is presented as a
curiosity, showing the effect of admission of steam to the
cylinder subsequent to the cut-off, due to the rebounding of
the valve after it had once closed. The diagram was taken
from the crank end of the cylinder.

ENGINE No. 76

297

ENGINE No. 77.

Elevator Engine, 8" x 10."

This is introduced as a curiosity, and at the same time it
reveals the wasteful character of this class of engine. There
is an absence of expansion and exceedingly high back pressure,
both of which are required by the exigencies of the service and
type of valve mechanism which that service necessitates. This
diagram also illustrates the effect of improper location of the
indicator on the cylinder. In this case it was placed at a short
distance from the end. of the stroke, so that the piston ring
covered the hole until it had moved a certain distance on the
forward stroke. The hump on the diagram is caused by this
defective location.

The diagram was taken on an upward trip.

ENGINE No.77

298

ENGINE No. 78.

Four valve (Corliss), 23" x 60." Speed, 74 rev. per min.

These diagrams furnish another instance showing the in-
fluence, or want of influence, of leakage. In this case the
trouble was with the piston. Diagram No. 78a was taken with
the piston leaking, the packing ring being broken, and No. 786
was taken when the ring had been renewed, and the piston
made tight. Feed-water tests made under both conditions
showed that the leaking engine used 34.5 Ibs. of steam per I. H.
P. per hour, and the tight engine, 27.7 Ibs. The difference is
about 20 °/0. The boiler pressure was higher after the repairs
than before, but this does not affect the general features. So
far as the expansion line is concerned, the leakage of the piston
had no appreciable effect. There is a noticeable difference in
the compression lines, but in the leaking engine this alone
would not prove the leakage in question. The diagrams are
from the crank end.

ENGINE No. 78a

ENGINE No. 78b

-60

-40

-20

0
1-80

-60

-40

-20

L 0

299

ENGINE No. 79.

Four valve (Corliss), cross compound, 24" and 44" x 72."
Speed, 61 revolutions per minute.

The main object in changing the adjustment of the valves in
this engine was to secure a greater amount of compression, and
a more quiet operation of the engine. Previous to the changes
there was considerable knocking in the main connections when
the centers were passed, and internal noises in both cylinders.
The effect of the changes was to almost wholly overcome these
defects in the running qualities. The adjustments consisted
in moving the eccentric of the high-pressure cylinder forward
jj" on the 12" shaft and the eccentric of the low-pressure
cylinder forward l£." The steam-valve rods of the high-pres-
sure cylinder were both shortened two threads, so as to give
earlier admission. The exhaust rods of the same cylinder were
lengthened 8 threads each, so as to increase the compression.
The steam-valve rods of the L. P. cylinder were shortened three
threads each, so as to give earlier admission ; and the exhaust
rods were each lengthened 6 threads, so as to obtain earlier com-
pression. To better reveal the effect of the changes, the dia-
grams are superimposed, the dotted lines being taken before,
and the full lines after, the adjustments.

300

ENGINE No. 79

lOO-
SC -
60-
40
20-
0-

H.P. Head End

H.P. Crank End

-!00

- 80

- 60
-40

- 20

- O

L.P. Head End

L.P. Crank End

ENGINE No. 80.

Four valve (Corliss) tandem compound, 18" and 30" x 48".
Speed, 63 revolutions per minute.

The low-pressure cylinder of this engine was operated by
double eccentrics. The diagrams here given show the effect
produced by advancing the eccentric which drives the exhaust
valves of the low-pressure cylinder 3-J-"on the 12" shaft. At
the same time the exhaust rod on the high-pressure cylinder was
lengthened 2 threads, so as to give greater compression. The
diagrams were taken at the head end of both cylinders, No.
80a before, and No. SOb after, the adjustments.

302

120-

100-

80-

60-

40-

20-

0-

ENGINENo. 8Oa

H.P. Cyl,

UP. Cyl.

- 15

- 10

- 5

- 0

O

- 10

ENGINE No. 8Ob

I20-,

100
80J
60
40-
20-

o-

H.P. Cyl.

L.P. Cyl.

- 15

- 10
— 5

- 0

- 5

- 10

ENGINE No. 81.

Compound duplex direct acting pumping engine.

These diagrams show the effect of increasing the throw of
the valves (which are slide valves), thereby giving the engine
the benefit of wider opening of ports. The improvement is
shown mainly in the increased effect of the vacuum in the low-
pressure cylinder. The effect of the change on the duty per-
formed by the pump was marked, and the consumption of coal
was much reduced. No. 8~La was taken before, and No. 81 b
after, the change.

ENGINE No. Sla

60

- 40

304

ENGINE No. 82.

Four valve cross compound, 24" and 46" x 48". Speed,
75 revolutions per minute.

The high-pressure cylinder of this engine is of the four-valve
type. The low-pressure cylinder has slide valves with cut-off
adjustable by hand. These diagrams show the effect upon the
distribution of the load between the cylinders produced by
changing the cut-off in the low-pressure cylinder. In one case,
No. 82 a, it was set at the J mark, and the other, No. 826, at the
| mark. In the former the power developed by the high-pressure
cylinder was 408 H. P., and by the low-pressure cylinder 300
H. P., while in the latter the quantities were respectively
480 and 222. The diagrams are from the crank end.

305

OF THK

UNIVERSITY

ENGINE No. 82a

H.P. Cyl.

100
-80
•60
-40
-20
- 0

L.P. Cyl.

- 10

- 5
- 0

— 5

L- 10

ENGINE No. 82b

H.P. Cyl.

r-100

80
_ 60

-40
-20
- 0

L.P. Cyl.

ENGINE No. 83.

Canadian cross-compound engine, 20" and 36" x 42". Speed,
76 revolutions per minute.

The high-pressure cylinder in this engine has Corliss valves
and the usual automatic cut-off. The low-pressure cylinder has
a plain slide valve with no means of adjusting the cut-off save
by shifting the eccentric. These diagrams show the effect
upon the distribution of the load between the cylinders pro-
duced by changing the low-pressure cut-off by the eccentric
adjustment. When the steam followed in the low-pressure
cylinder to nearly full stroke No. 83 a, the power developed in
the high-pressure cylinder was 167 H. P., and in the low-pres-
sure cylinder, 60 H. P. When the eccentric was advanced in
the low-pressure cylinder, No. 83 &, these quantities became
respectively 149 H. P. and 80 H. P.

307

ENGINE No. 83a

H.P. Cyl.

— 60

-40

-20

- 0

L.P. Cyl.

ENGINE No. 83b

H.P. Cyl.

^60

-40

- 20

L- 0

L.P. Cyl.

ENGINE No. 84.

Four-valve cross compound, 17y and 28" x 48". Speed,
100 revolutions per minute.

This engine is a non-condensing compound. The valves are
all slide valves, and the steam and exhaust are operated by in-
dependent eccentrics. The diagrams show the effect produced
by changing the cut-off on the low-pressure cylinder, and there-
by the pressure in the intermediate receiver. Diagram 84 a
was taken with a receiver pressure of 44 Ibs., and diagram
84 b with a receiver pressure of 27| Ibs. They are all from the
crank end.

309

40-
30
20-
10-

o-

30-

20-

10-

O-

ENGINENo. 84a

H.P. Cyl.

-120
-100
—30
-60
-40
-20
— 0

L.P. Cyl.

ENGINE No. 84b

H.P. Cyl.

-120
-100
-80
-60
-40
-20
0

L.P. Cyl.

ENGINE No. 85.

Four-valve (Corliss) cross-compound, 24" and 34" x 48".
Speed, 61 revolutions per minute.

In this engine the governor operated on the cut-off of the
high-pressure cylinder. The cut-off of the low-pressure cylin-
der was under the control of a pressure regulator set so as to
maintain a constant pressure in the receiver, irrespective of the
load or other conditions. Steam was withdrawn from this
receiver for heating purposes ; in this case for the heating of
feed- water for the plant of boilers which supplied the engine,
and the diagrams given were taken under two conditions of
running ; first, No. 85 a, when all the steam was used for
power, and second, No. 856, when the steam was withdrawn
from the receiver as noted.

311

ENGINE No. 85a

H.P. Cyl.

-100
-80
-60
—40
-20
- 0

L.P. Cyl.

r I0

o

- 0
— 5

- 10

ENGINE No. 85b

H.P. Cyl.

-100
-80
— 60
-40
-20
- 0

UP. Cyl.

-10

- 5

- O

- 5
-10

ENGINE No. 86.

Four-valve cross compound, 20" and 36" x 48". Speed, 65
revolutions per minute.

The condenser of this engine is the siphon type, and the
injection water is supplied by an independent direct-acting
steam pump. This is arranged so as to exhaust into the
receiver or into the condenser, as desired. The diagrams given
were taken under both of these conditions of running the pump ;
those with the full lines being taken when the pump was ex-
hausting into the receiver, and those with dotted lines when
the same was turned into the condenser. The comparatively
poor vacuum in the latter is due to the air leakage through the
packing around the valve stems and piston rod of the pump.

ENGINE No. 86

H.P. Cyl.

L.P. Cyl.

—100

- 80

- 60
40

- 20

0

- 15

- IO

- 5

- 5

- 10

313

ENGINE No. 87.

Single-valve cross compound, 15" and 23" x 15". Speed,
260 revolutions per minute.

This engine has unpacked piston valves, one for each cylin-
der, with a shaft governor operating on the high-pressure valve.

These diagrams are given to show the effect of a break in
the casting of the high-pressure steam-chest, which allowed
steam to pass directly into the low-pressure chest without going
through the high-pressure cylinder. The two cylinders and the
chest were all made in one casting. Diagrams No. 87a and
876 were taken with a load of 79.5 I. H. P., and No. Sic and
Sid with a load of 131.1, I. H. P. In the former the low-
pressure cylinder developed 155.2 H. P., and in the latter 141.3
H. P. In the former the high-pressure cylinder produced a
resistance or negative power equivalent to 75.7 horse-power,
while in the latter this was reduced to 10.2 horse-power. The
difference in these quantities gives the respective horse-powers
as stated. In diagram 87 a the upper line, which ordinarily
is the steam and expansion line, is here the compression line,
and the lower line is the one that is made during the admission,
expansion, and release. The boiler pressure here is 75 Ibs., and
the compression of the exhaust carries the back pressure up
to 120 Ibs. The point of cut-off takes place at the very begin-
ning of the stroke, and evidently there is no steam admitted
save that which comes from the compression of the exhaust.

Diagrams Sle and 87/ were taken from an engine of the
same size and make, in which there was no defect such as that
mentioned ; and a comparison with these will show the effect
produced by the disordered condition. In these diagrams the
high-pressure cylinder developed 71.4 I. H. P., and the low-
pressure 53.3, making a total for the engine of 124.7 I. H. P.
This is about the same power as that shown by diagrams Sic
and Sid.

These diagrams are all from the crank ends.

314

ENGINE No. 87a

25-
20-
15-
10-
5-
0-
5-
10-

20-
15-
10-
5-
0-
5-
10-

H.P. Cyl

100
80
60
40
20
- 0

ENGINE No. 87b
L.P. Cyl,

ENGINE No. 87c
H.P. Cyl.

- 40

20

"- 0

ENGINE No. 87d
L.P. Cyl.

ENGINE No. 87e

H.P. Cyl.

ENGINE No. 87f

L.P. Cyl.

- 60
-40

- 20

- 0

ENGINE No. 88.

Marine triple expansion engine, 15", 23", and 40" x 30".
Speed, 83£ revolutions per minute.

These diagrams show the effect produced by leakage of the
low-pressure piston. The dotted line on the low-pressure dia-
gram is the one taken when the leakage was going on, and the
full line the one taken with a tight piston. The diagrams S8a
from the intermediate and high-pressure cylinders are those
taken with the tight engine. The effect of stopping the leak-
age, which was due to the weakness of the springs under the
packing-rings, was to raise the pressure in the receiver. The
increase was 4-lbs. Another effect was to increase the speed
of the engine when running at full capacity from 81 revolutions
per minute to 84. Still another effect was to increase the power
developed from 410 I. H. P. to 442 I. H. P.

ENGINE No. 88a

H.P. Cyl.

140-
120-
100-
80
60-
40-
20-

ENGINENo. 88b
L.P. Cyl.

5-
0-
5-
10-

317

ENGINE No. 89.

Compound high-speed non-condensing engine, 6" and 12" x
12". Speed, 201 revolutions per minute.

These diagrams are given simply as curiosities. The high-
pressure cylinder is doing nearly all the work, and the condi-
tions under which the steam is distributed are about as wasteful
as could occur. There is no cut-off in the high-pressure cylin-
der ; the terminal pressure is the highest of any part of the
diagram, the release is late, and the back pressure on the low-
pressure diagram is excessive.

-60

— 40

— 20

— 0

L.P. Cyl.

- 40

- 20

318

ENGINE No. 90.

Diagrams 90 a and 90 b are introduced partly as curiosities
and partly to show the general features of diagrams obtained
from a steam-driven air-pump operating an independent con-
denser. Here the cylinder was 10" x 10". Diagram 90 a was
taken when the pump exhausted into the condenser, and dia-
gram 90 b when it exhausted into the atmosphere. The pecu-
liarity of these diagrams lies in the fact that the pump takes
steam at full stroke, exhausts at a higher pressure than the
pressure of admission ; and the return stroke is made, for a por-
tion at least, under the wasteful conditions of a very high back
pressure. Another curiosity is the stopping of the piston at
about the middle of the stroke, and the rebounding of the same
before it proceeds on its course.

When this pump was running non-condensing the exhaust
steam was measured by collecting and condensing it in a barrel
of water. It was found to use 717 Ibs. of steam per hour, at a
speed of 61.2 double strokes per minute, or 103.3 Ibs. of steam
per I. H. P. per hour, the power developed being 6.94 H. P.
This performance represents, as might be expected, a very
wasteful use of steam ; but it should be stated that in a plant
properly arranged the heat of the steam can be utilized in
warming the feed-water, and the loss is reduced to a compara-
tively small quantity.

319

ENGINE No. 9Oa

Head End

Crank End

ENGINE No. 9Ob
Head End

Crank End

-40
-20

0
10

-40
-20

- O

- 10

-40

-20

- 0

-40

-20

STEAM -PIPE DIAGRAMS.

321

STEAM-PIPE DIAGKAMS.

THE effect which a running-engine has upon the pressure in
the steam pipe, as shown by an indicator diagram taken from
the pipe, is a matter which not only possesses interest from an
engineering point of view, but it has a bearing on an important
question relating to steam-pipe design. The fluctuations of
pressure in the pipe caused by the intermittent flow of steam
into an automatic cut-off engine is sufficient to set up vibrations
in the pipe ; and these extend from the engine through the
whole distance back to the boiler unless the pipe is well an-
chored, and sometimes in spite of what appears to be good
anchorage. When we consider the relatively small weight of
the substance which is traveling through the pipe, it is difficult
to realize the powerful effect which these fluctuations have upon
its stability. It is not, however, the substance itself which is
the potent factor in the matter, but the effect of the unbal-
anced pressure acting between the two ends of a section of pipe
produced by the sudden and intermittent reduction of pressure
at the end nearest the engine. If the reduction is 10 Ibs. and
the diameter of the pipe is 8", there is an unbalanced pressure
of 10 Ibs. per square inch upon an area of about 50 square
inches, or a total force of 500 Ibs. acting in the direction of the
length of the section. Such a force would have in a measure
the effect of a 500 Ib. blow upon the pipe, which, of course, is
a serious matter. These fluctuations can be overcome to some
extent by avoiding short right^angle elbows, and employing
long-turn bends in their place. They can be overcome more
effectually by introducing in the steam pipe as near as possible
to the engine a reservoir having considerable volume relative
to the size of the cylinder, and passing the steam through the
large space thus provided. The fluctuations will then occur

323

324 ENGINE TESTS.

mainly in that part of the pipe which lies between the reservoir
and the cylinder, and the reservoir serves to prevent them to a
large extent from extending back to the boiler. The steam-
pipe diagrams here given show the desirability of employing
some means for reducing the extent of these fluctuations, and
in one instance the beneficial effect of a reservoir is clearly
revealed.

ENGINE No. 91.

Diagrams 91« and 916 were taken from a 9" steam pipe
supplying a 28" x 48" Corliss non-condensing engine running
at a speed of 100 revolutions per minute. The pipe is a
branch from a long 12" pipe leading to the boilers, and its
length measured from the 12" is about 30 feet. The pipe
contains 6 short right-angle elbows. Diagram 91# is com-
plete for the entire revolution of the engine, and reveals the
pulsations produced by the admission at both ends of the
cylinder. Diagram 91# relates to one stroke. The indicator
diagram from the cylinder taken on the same stroke is also
shown.

60-
40-

20-

0-
80-

60-

40-

20-

0 —

ENGINE No. 91a

It will be seen that just before the beginning of the stroke
the pressure in the steam pipe drops ; and it is maintained nearly
constant until the cut-off takes place, when it immediately rises.

325

326 ENGINE TESTS.

Afterwards the pressure gradually falls, and a short time before
the opposite end of the stroke is reached it rises again. Subse-
quently when the very end is reached it falls abruptly, co-
incident with the admission of steam to the other end of the
cylinder.

ENGINE No. 92.

Diagrams 92a and 926 are from an 8" steam pipe supply-
ing a 23" x 60" non-condensing Corliss engine running at
a speed of 75 revolutions per minute. The pipe is 82 feet
in length, measured from the nearest boiler to the throttle
valve, and it contains 5 short right-angle elbows. Diagram
92# applies to a complete revolution, and 926 simply to
the forward stroke taken while the piston was moving from

ENGINENo.92a

-80
-60
-40
-20

— 0
-80

-60
-40
-20
- 0

the head end of the cylinder. The indicator diagram from the
head end of the cylinder is also given. Referring to the latter,
it appears that just prior to the beginning of the stroke the
pressure rises in the steam pipe. Coincident with the move-
ment of the piston forward during the admission, the pressure
in the pipe gradually falls up to the point of cut-off, and when
this occurs it rises to a point some 10 Ibs. above the line of

327

328 ENGINE TESTS.

average pressure. At a point just beyond the middle of the
stroke the pressure gradually falls, until just before the end
of the forward stroke it suddenly rises again preparatory to
the beginning of the return stroke.

This diagram is a curiosity for the reason that the pressure
rises at the very beginning of the stroke, when presumably the
cylinder is taking steam, whereas under the ordinary circum-
stances it would be expected that the operation would be
reversed and the pressure would fall. The probability is that
owing to the compression of the exhaust steam into the clear-
ance space the quantity of live steam admitted is very small.

Another curiosity in this diagram is the fall of pressure
from the middle to nearly the end of the stroke. During this
period there is no steam being drawn out of the pipe, and the
only explanation of this action is the assumption of a sort of
rebounding of the steam within the pipe due to the intermit-
tent character of the flow. In this matter as well as in the
conformation of the diagram throughout, there are many points
which, to say the least, are obscure.

ENGINE No. 93.

This diagram is from a 1" pipe supplying a Corliss con-
densing engine, 32" x 54", making 47 revolutions per minute.
The engine diagram given is from the crank end of the
cylinder, and the steam-pipe diagram refers to one stroke of
the piston, that is, the one made from the crank end to the
front end. This engine was one cylinder of a pair, and the
steam pipe consisted of a 10" main leading from the boilers
and a 7" branch to each cylinder. The distance from the
10" to the throttle valve was 20 feet, and it contained two
right-angle elbows. The other cylinder was in operation when
the diagram was being taken.

80^

60 —

40-

20-

o-

10-

On the steam-pipe diagram it appears that the pressure rises
just before the beginning of the stroke, and immediately after
it drops back to nearly the same point, and remains nearly con-
stant until the steam is cut off from the cylinder, when it
rises. Just before the middle of the stroke the pressure falls
again, this action being due presumably to the other cylinder
taking steam, followed by another rise in the pressure at about
the time of the cut-off in the other cylinder. Just prior to
the beginning of the return stroke the pressure rises as before,
and again drops soon after the beginning of the return stroke,
when the other end of the cylinder begins to take steam.

329

330 ENGINE TESTS.

Here is another curiosity. At the very beginning of the
steam-pipe diagram the pressure increases in a marked degree
at the time when apparently the cylinder begins to take steam,
and then immediately drops back. The reason for this action
is difficult of explanation.

ENGINE No. 94.

Diagram No. 94 is from the steam pipe of the right-hand
cylinder of a pair of double-valve engines, 17" x 24", running
at a speed of 154 revolutions per minute.

ENGINE No. 94

—60
-40
-20
— 0

The main pipe here was 140 feet in length, 10" in diameter,
and had 3 short right-angle elbows. The branch pipe for the
two cylinders were each 6" in diameter and 8' in length, and
each contained 2 righkangle elbows. This is the same engine
as that referred to as No. 10 in the section on Feed-Water
Tests, but it was taken with an indicator having a different
scale from the diagrams given in connection with the results
of those tests.

It will be seen in this diagram that the effect of the closing
of the valves at the points of cut-off are clearly revealed, but
that in other respects the various operations are not clearly
defined. Considering that the reciprocations are somewhat
rapid, and that the diagram shows the effect of the fluctua-
tions produced by both cylinders, it is difficult to make a close
study of its various features.

331

ENGINE No. 95.

Diagram No. 95 is from the steam pipe of a 20" x 50" four
valve engine making 65 revolutions per minute.

-70
-60
-50
-40
-30
-20
- 10
0

The pipe is 5" in diameter and 36' long, and it contains 4
short right^angle elbows. This is the same engine as the one
numbered 76 under the head of Valve Setting. The features
in this diagram conform in the main to what would be expected
from the known operations of the steam. The pressure drops
at the beginning of the stroke, and rises at the point of cut-
off ; and when the opposite end of the stroke is reached it drops
again, coincident with the opening of the steam valve, and
rises again when the cut-off at the other end takes place. One
feature here is noticeable ; and that is, that the effect of the
subsequent admission after the cut-off, which is shown on the
diagram taken from the cylinder, the same as in No. 76, is
clearly revealed on the steam-pipe diagram, where there is a
second fall of pressure just beyond the point where the rise
occurs due to the regular cut-off. The fall of pressure com-
mencing at the middle of the stroke and continuing to near the
end is a feature of this diagram the same as in some of the
preceding ones which have been referred to, though here it
takes place more gradually than in some.

332

ENGINE No. 96.

Diagrams 96# and 96& are from the head end of a Corliss
condensing engine, 20" x 48" running at a speed of 60 rev-
olutions per minute.

100-

80-
60-
40-
20-

0
IOJ

100-

80
60-
40-
20-

0-

10

This engine is one of a pair ; but when these diagrams were
taken, the second cylinder was out of use, and the throttle
valve closed. The main pipe here is 10" in diameter and 33'
in length. The branches are 6" in diameter, and the one lead-
ing to the left-hand cylinder is 10' in length, and that to the
right-hand cylinder 15' in length. Each of these branches
has two short right-angle elbows. The diagrams were taken
from the left-hand cylinder. Diagram 96a was taken when the
steam was passing through the pipe above referred to. When

333

334 ENGINE TESTS.

diagram 965 was taken the 10" pipe was shut off at the boiler
end, and steam was furnished through twenty-five feet of 8" pipe
and one 45 degree elbow into a tee at the boiler end of the 10"
main. In both these diagrams the admission of steam is accom-
panied by a drop of pressure in the pipe, as would be expected,
and a corresponding rise of pressure at the point of cut-off. In
diagram 96a the pressure falls again very quickly after cut-off ;
and a succession of wavy lines occur until the middle of the
stroke, and then the pressure is nearly constant to the end. In
diagram 96£, on the contrary, the fall of pressure just after the
cut-off is much less marked, and there is considerable more rise
in pressure as the end of the stroke is approached. The only
difference in the conditions under which these diagrams were
obtained was in the lengthened pipe through which the steam
passed. It would seem, therefore, that the arrangement of the
pipe has much to do with the character of the fluctuations.
It will be noticed also in these diagrams that the fluctua-
tions resemble in some respects those which occur on previ-
ous diagrams taken from a pair of engines with both cylin-
ders running. In this case, however, only one cylinder was
in operation. Here is another indication that the arrangement
of the pipe has much more effect upon the character of the
fluctuations than would at first be supposed.

ENGINE No. 97.

Diagram No. 97 is from a 10" steam pipe supplying a SO''
x 72" Corliss engine, making 60 revolutions per minute.

ENGINE No. 97

-80

-60

-40

-20

— 0

- 10

The steam pipe is 108 feet in length from the main header
in the boiler-room, and it contains five short right-angle elbows.
The fluctuations of pressure here are of much less extent than
in any of the preceding diagrams, due in part probably to the
relatively light load on the engine. In view of what the pre-
ceding diagrams have shown, the real cause of so little variation
may be some peculiar arrangement of the pipes which acted
favorably.

335

ENGINE No. 98.

Diagram No. 98 is taken from an 8" steam pipe supplying
a 24" x 48" Corliss engine running at a speed of 62 rev-
olutions per minute.

-100
-80
-60
-40
-20

- 0

- 10

The pipe is 135 feet in length, and contains 5 short right-
angle elbows and two 45 degree elbows. The lines in this
diagram are very clearly marked. There is a sudden drop in
the pressure just at the beginning of the stroke, and there is a
marked rise of pressure at the point of cut-off. There seems to
be little variation of pressure after this time until nearly the
end of the stroke. During the very last part of the stroke,
however, the pressure drops the same as noticed in many of the
preceding diagrams, although there appears to be no action in
the working of the steam in the cylinder that should cause it.
This is one of the things that makes the reasons for the par-
ticular conformation of steam-pipe diagrams obscure.

ENGINE No. 99.

Diagram No. 99 was taken from a 6" pipe supplying a 14"
and 26" x 42" compound engine running at a speed of 100
revolutions per minute.

-'40

-120

-100
80

- 60
— 40

- 20

0

The length of the pipe was 75 feet, and it contained two
short right-angle elbows. Here is another case where the lines
of the diagram are clearly marked, and there can be no miscon-
ception in regard to the action going on in the pipe. This dia-
gram is similar to the one which precedes it, and has the same
general features. There is this peculiarity, however, that there
is practically no drop of pressure during the period of admis-
sion. The drop occurs toward the very end of the previous
stroke. Subsequent to the cut>off and prior to this drop, the
pressure is well nigh constant. The indicator diagram here
given is from the head end, and refers simply to the high-
pressure cylinder.

337

ENGINE No. 100.

Diagram No. 100 refers to a case where a reservoir was
installed in the steam -pipe close to the cylinder, and the dia-
gram was taken from this reservoir. The engine is a Corliss
30" x 48", running at a speed of 80 revolutions per minute.
The receiver is supplied from an 8" pipe 223 feet in length,
which contained six short right-angle bends, while the engine
is supplied from the reservoir through a 10" pipe 12" long,
containing two short right-angle elbows. The size of the
reservoir is 42" in diameter and 8' in height.

roo-

80-
60-
40
20

0-
10-

ENGINENo. 100

In this diagram the fluctuations of pressure do not seem to
follow the admission and cutting off of the steam to any great
extent, and at the worst they are confined within narrow limits.
The extreme change of pressure from the highest to the lowest
is three pounds. Comparing this with the previous instance,
No. 99, the difference is exceedingly marked. There the change
of pressure was some thirteen pounds. If we investigate these
two cases carefully it will be found that the rate of flow of
steam from the boiler to the reservoir is forty-three feet per
second, and in the other case (No. 99) the rate of flow close to
the throttle valve was twenty-eight feet per second. The con-
ditions as to the speed of the steam and the quantity with-
drawn per stroke with reference to the size of the pipe was

ENGINE No. 100. 339

therefore much more severe in the case where the reservoir was
used. It thus appears that with the same conditions of service,
the favorable effect produced by the reservoir would have been
even greater than that here indicated.

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