An ordinance for construction of chimneys suitable for use in cities and towns of any size or as a state law

TH

AN ORDINANCE

FORj

CONSTRUCTION OF CHIMNEYS

Suitable for Use in Cities
and Towns of Any Size

OR AS A

State Law ,% ; - ••

Recommended by the

NATIONAL BOARD OF FIRE UNDERWRITERS
COMMITTEE ON CONSTRUCTION OF BUILDINGS

SECOND EDITION, REVISED

1921

Foreword

THE average annual loss due to defective chimneys in the United
States for the years 1916-19, inclusive, and reported by the Actuarial
Bureau to the National Board of Fire Underwriters was $11,898,000.
All losses were not reported and it is conservatively estimated that the
complete actual loss was 25 per cent, larger, thus making an approximate
total loss per year of $14,872,000. The number of lives sacrificed in the
average 23,000 fires which produced this annual property loss is not known,
but is unquestionably large.

Since fires from this cause are classed as "strictly preventable," it
should need no further argument to justify the promulgation of this
Ordinance, which is suitable for adoption by a town of any size, or for
enactment as a state law. The latter form would be the most effective.

Conservation of our national resources is the demand of the hour.
It is, therefore, the duty of all state and municipal authorities' to use
their best endeavors to stop this great needless waste. The enforcement
of a law requiring safe, smoke-tight construction of chimneys of ample
size and height would be a sure means of accomplishing an immense
saving in life and property as well as materially increasing home comforts.

Defective chimney fires would practically disappear if this Ordinance
were generally enforced, and since the additional cost of the construction
herein recommended as compared with ordinary practice would seldom
exceed $10 to $15 per chimney, the requirement would not be burdensome.
The increased expense would be returned many fold due to saving of life
and property and the efficient use of fuel.

The following organizations have reviewed this Ordinance and ap-
proved it as here presented. We desire to express our appreciation for
helpful assistance rendered by several of these :

American Institute of Architects,

American Society of Heating and Ventilating Engineers,
Associated Tile Manufacturers,
Clay Products Association,
Common Brick Manufacturers Association,
Eastern Clay Products Association,

National Boiler and Radiator Manufacturers Association,
National Fire Protection Association,
National Brick Manufacturers Association,
National Lime Association — Eastern Bureau,
National Lumber Manufacturer's Association,
National Warm Air Heating and Ventilating Association,
Also various independent Architects and Heating Engineers having
wide experience in the subject.

465855

This broad endorsement gives the requirements a reputation for
correctness which has not been accorded to any similar set of specifications
hitherto prepared. It is, therefore, hoped the Ordinance may receive
generous public approval, and become a construction standard in states,
cities and towns throughout the country. We urge its adoption.

National Board of Fire Underwriters,

Committee on Construction of Buildings.

E. T. CAIRNS, Chairman,

F. W. DAY, R. C. CHRISTOPHER,

CHAS. H. HAHN, J. A. KELSEY,

JOHN W. EMERY, A. W. PERRY,

E. G. PIEPER, J. M. WENNSTROM.

The Ordinance was drafted for the Committee by its Consulting
Engineer, to whom correspondence in reference to same should be sent.

Address

IRA H. WOOLSON, Consulting Engineer,
National Board of Fire Underwriters,

76 William Street, New York City.

Should copies of the Plates used in the Ordinance be desired they will
be furnished at the cost of duplicating the electrotypes.

AN ORDINANCE

Providing Minimum Requirements for Proper and
Safe Construction of Chimneys, Flues and Fireplaces in

the of

Scope of the Ordinance.

This Ordinance does not apply to chimneys for high pres-
sure boilers, furnaces used in manufacture, or for other heating
appliances where high temperatures are maintained; but shall
apply to all other chimneys which form a part of a building con-
struction.

Section I. Chimney Construction.

1. The walls of all chimneys to which this Ordinance ap-
plies, whether the fuel used be wood, coal, gas or oil, shall be
built of brick, concrete, stone, or hollow tile, of such thickness
and construction as is hereafter specified, but this shall not pre-
clude the use of a metal smoke-stack when located inside of a
vent shaft having walls not less than 8 inches thick, and having
an air space between the walls and stack on all sides.

2. Brick chimneys shall be built of solid brick, or may be
built of perforated radial brick manufactured for the purpose
and adapted to withstand high temperatures, but no other hollow
brick shall be used.

3. The walls of brick chimneys shall be not less than 3^4
inches thick (width of a standard size brick), and shall be lined
with fire clay flue lining.

4. Flue lining may be omitted in brick chimneys for private
dwellings provided the walls of the chimneys are not less than
8 inches thick, and that the inner course shall be a refractory
clay brick having a softening point of at least 1922 degrees
Fahrenheit (Seger Cone 05). See Appendix I and II.

5. Perforated radial brick chimneys may be unlined, pro-
vided the brick shall have a softening point of not less than 1994
degrees Fahrenheit (Seger Cone 03), and shall be not less than

3

7^2 inches in radial thickness, except that when such chimney
is located inside a vent shaft having walls not less than 8 inches
thick, the thickness of the chimney wall may be determined
by engineering design. The brick shall be shaped to the circular
and radial lines of the various sections of the shaft so as to form
even joints.

6. All brick work shall be laid in spread mortar, with all
joints push-filled. Exposed joints both inside and outside shall
be struck smooth. No plaster lining permitted.

7. Concrete chimneys cast in place shall be suitably rein-
forced vertically and horizontally. The walls shall be not less
than 334 inches thick and shall be lined with fire clay flue lining.

Flue linings may be omitted in reinforced concrete chimneys
for private dwellings, provided the walls of the chimneys be
not less than 6 inches thick, and provided further that quartz
gravel shall not be used as the coarse aggregate. See Ap-
pendix III.

8. Concrete blocks used in chimney construction shall have
walls not less than 334 inches thick, and blocks enclosing more
than one flue shall have suitable reinforcement completely en-
circling the blocks and well embedded in them. All concrete
block chimneys shall have fire clay flue lining. See Appen-
dix III.

9. Stone chimneys shall be at least 4 inches thicker than
required for corresponding brick chimneys, and shall have fire
clay flue linings. Rubble stone chimney walls shall be not less
than 12 inches thick.

10. Hollow building tile shall not be used for the walls of
isolated or independent chimneys, but may be used for chimneys
built in connection with exterior hollow tile walls of buildings
not exceeding three stories in height, in which case the chimney
walls shall be not less than 8 inches thick. The outer 8 inches
of a building wall may serve as the outside wall of the chimney,
but the remaining chimney walls shall be constructed of two layers
of 4-inch tile set with broken joints ; or they may be built of 4
inches of solid brickwork. In either case the walls of the

chimney shall be securely bonded into the wall of the building.
No chimney shall be corbeled from a hollow tile wall. All chim-
neys built of hollow building tile shall have fire clay flue lining.
See Appendix IV.

11. Chimneys shall be built at least 3 feet above flat roofs,
and 2 feet above the ridges of peak roofs, and shall be properly
capped with stone, terra cotta, concrete, cast iron, or other
approved material ; but no such cap or coping shall decrease the
required flue area. See Plates I and II.

12. Fire clay flue linings shall be manufactured from suit-
able refractory clay, either natural or compounded, which has a
softening point not lower than 1994 degrees Fahrenheit (Seger
Cone 03), and shall be adapted to withstand high temperatures
and flue gases. They shall be of standard commercial thickness,
but not less than £4 inch. The flue sections shall be set in mortar
of quality hereafter specified and shall have the joints struck
smooth on the inside. The masonry shall be built around each
section of lining as it is placed, and all spaces between masonry
and linings shall be completely filled with mortar. No broken
flue lining shall be used. Flue linings shall start at least 4 inches
below the bottom of smokepipe intakes of flues, or from the
throats of fireplaces, and shall be continuous the entire
heights of the flues and project at least 4 inches above
chimney top to allow for a 2 inch wash and a 2 inch projection of
lining. The wash or splay shall be formed of a rich cement
mortar. To improve the draft the wash surface should be con-
cave wherever practical. Instead of the wash, a special chimney
cap or coping may be used. Wherever flue linings are specified
fire brick may be substituted if desired.

13. Chimneys shall not rest upon or be carried by wooden
floors, beams or brackets, nor be hung from wooden rafters.
Iron brackets or stirrups attached to wooden construction shall
not be used to support chimneys. In frame buildings chimneys
shall always be built from the ground up, or rest on basement
walls.

14. Chimneys shall be built upon concrete or masonry
foundations properly proportioned to carry the weight imposed

5

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JTANDAR.D CHIMNEY CONSTRUCTION-

JEQTION '&

PLATE I.

Elevation and section of an interior independent chimney showing
recommended construction. Extra flues can be added as desired.

without danger of settlement or cracking. The foundation for
an exterior chimney shall start below the frost line.

15. The walls of brick buildings may form part of a chim-
ney, but the walls of the chimney shall be securely bonded into
the walls of the building, and the flue shall be lined the same
as an independent chimney. Flues in party walls shall not ex-
tend beyond the center of the walls, and their location shall be
permanently indicated on the exposed side of the wall.

16. No wall less than 12 inches thick shall be used to sup-
port a corbeled chimney; such corbeling shall not project more
than 6 inches from the face of the wall, and in all such case?
the corbeling shall consist of at least five courses of brick.

17, Flues shall be built as nearly vertical as possible, but in
no case shall they have an angle greater than 45 degrees from
the vertical. Where flues change direction, the abutting linines
at the angle joints shall be chipped to fit closely, and at no point
shall the cross section area be reduced. There shall be but one
connection to a flue.

18. Not more than two flues shall be permitted in the same
flue space, and the joints of any two adjoining sets of flue lin-
ings shall be offset at least 7 inches. When there are more
than two flues in a chimney, at least each third flue shall be separ-
ated from the others by a smoke-tight withe or division wall of
brick or concrete at least 3^4 inches thick and bonded into
the sidewalls. Each flue intended for a heating furnace or boiler
connection, or for a fireplace, shall be separated from other
flues by such a withe. In hollow tile chimneys the withe may
be of tile. See Appendix V.

19. When any single flue area within chimney walls exceeds
200 square inches, the walls shall be built not less than 8 inches
thick and shall have fire clay flue lining as previously specified,
but when flues become so large as to render it impractical to
secure fire clay flue lining, they shall be lined with fire brick for
a distance of at least 25 feet from the point of intake. Fire
brick shall be laid in fire clay mortar.

7

N6-F-U-

192.1

PLATE II.

Details of chimney construction showing method of flashing at roof
surface, also a wash course, but no cap surrounding flues at top. See
Plate I.

20. Connections between chimneys and roofs shall be made
with sheet metal counter or cap flashing (copper recommended),
arranged to overlap roof flashing and allow for movement that
may occur between chimneys and roofs. See Plates I and II.

21. No increase in the wall thickness of chimneys, nor
any projecting masonry, shall /be permitted within a distance
of 12 inches above or below the rafters or roof joists.

22. Irrespective of whether the fuel used be coal, coke,
wood, or oil, the minimum area inside of chimney flue linings for
various heating devices shall be as follows : For warm air fur-
naces, or low pressure steam or hot water heating boilers, not less
than 75 square inches ; for fireplaces, not less than one-tenth the
area of the fireplace opening, but never less than 75 square inches ;
for stoves, ranges, and other forms of room heaters, 49 square
inches for rectangular flues, or an inside diameter of 7 inches
for round flues. In no case shall the short cross section dimen-
sion of a rectangular flue be less than two-thirds the greater
dimension. See Appendix VI.

When gas is the fuel used in a heating furnace, boiler, or
automatic hot water heater, the flues shall be of the same size
and construction as required for stoves and ranges using other
fuel. Vent flues where required for other domestic gas burn-
ing appliances may be of smaller size, but not less than 10 square
inches. Such flues shall be made of fire clay or its equivalent
not less than 1 inch thick with joints properly designed to effect
a permanent seal, and the surrounding masonry walls may be
omitted. Metal vent flues are not permitted.

23. Smokepipe intakes to flues shall always enter the chim-
ney through the side and shall consist of fire clay or metal
thimbles securely set in the chimney wall with mortar, or the
intake may be cast in concrete. Such openings shall be at least
18 inches below wooden lath and plaster or other combustible
ceilings, or open joists. Neither the intake pipe nor thimble
shall project into the flue. No woodwork shall be placed within
6 inches of the thimble. The thimble shall be surrounded by
metal lath and plaster for a space of at least 6 inches, or an open
space of that width shall be provided on all sides. See detail
sketch Plate I.

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PLATE III.

Fig. 1.— Method for building two fireplaces back-to-back
in a brick party wall to secure proper spacing between ends of
floor joists.

Fig. 2. — Floor framing around a single fireplace. Note
filling between framing and brickwork, which serves both as
insulator and fire-stop.

10

FIG.1

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PLATEIV.

METAL LATH

Fig. 1. — Floor framing around chimney in a party wall, to secure
proper space between ends of floor joists.

Fig. 2. — Ordinary floor framing around a chimney. All timbers 2
inches cl-ear of brickwork and space filled with fireproofing material.

Fig. 3. — Stud partition across back of a chimney showing proper
method of arranging studs.

Fig. 4. — Stud partition across back of a fireplace and around the ends
of the chimney breast, showing proper arrangement of studs. Method
of fire-stopping this space is shown on chimney section, Plate I, also in
Fig. 2, Plate III.

11

24. All mortar used in chimney construction, except as
specified for fire brick in paragraph 19, shall be cement mortar
proportioned as follows : Two bags of Portland cement, not
less than 188 pounds, and one bag of dry hydrated lime, 50
pounds, thoroughly mixed dry. To this mixture shall be added
three times its volume of clean, sharp sand with sufficient water
to produce proper consistency. When dry hydrated lime is not
available, 1 cubic foot of completely slaked lime putty may
be substituted for 50 pounds of dry hydrate. In case of such
substitution, the mixing of lime and cement shall be very
thorough. Dry hydrate should always be used in preference to
lime putty.

25. After a chimney has been completed, all flues shall be
thoroughly cleaned and left smooth on the inside.

26. All flues to which heating furnaces or boilers are to
be connected shall be subjected to a smoke test before acceptance,
but the test shall not be made until the mortar has thoroughly
hardened. The method of test is to build a smudge fire at bot-
tom of the flue and while the smoke is flowing freely from the
flue, close it tightly at the top. Escape of smoke into other flues
or through the chimney walls indicates openings that shall be
made tight before the chimney is accepted. The test shall be
made by the contractor in the presence of the Building Inspector
or other official having jurisdiction, and of the owner or his
representative.

Section II. Woodwork Around Chimneys.

1. No wooden beams, joists, or rafters shall be placed
within 2 inches of the outside face of chimneys, whether the same
be for smoke, air or any other purpose. No woodwork shall be
placed within 4 inches of the back wall of any fireplace. See
Plate III, Fig. 2, and Plate IV, Fig. 4.

2. All spaces between chimneys and wooden joists or beams
shall be filled with loose cinders, loose mortar refuse, gypsum
block, or other porous incombustible material to form a fire-
stop. See Plates I, III and IV.

12

The incombustible material shall be supported by strips of
sheet metal or metal lath set into the brickwork and nailed to
the wooden beams, forming a buckled flexible joint between, as
indicated in Plate I ; or by similar strips of metal nailed to
the woodwork with the inner edge close to the chimney. See
Plate V.

3. No wooden studding, furring, lathing, or plugging shall
be placed against any chimney, or in the joints thereof. Wooden
construction shall either be set away from the chimneys, or the
plastering shall be directly on the masonry or on metal lathing
or on incombustible furring material. Wood furring strips placed
around chimneys to support base or other trim shall be insulated
from the masonry by asbestos paper, at least ^6-inch thick, and
metal wall plugs or approved incombustible nail holding devices
attached to the wall surface shall be used for nailing. See
Plate V.

AS&RTOS B>OAtk
&ACK Or WOOD

METAL
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PLATE V.

Detail showing support for fire-stopping around chimney,
and protection for woodwork placed next to plaster on chimney
brickwork.

13

4. The walls of fireplaces shall never be less than 8 inches
thick, and if built of stone the minimum thickness shall be 12
inches.

5. All fireplaces and chimney breasts shall have trimmer
arches or other approved fire-resistive construction supporting
hearths. The arches and hearths shall be at least 20 inches
wide measured from the face of the chimney breast. The arches
shall be of brick, stone or hollow tile, not less than 4 inches
thick. A flat stone or a reinforced concrete slab may be used to
carry the hearth instead of an arch if it be properly supported
and a suitable fill be provided between it and the hearth. The
length of trimmer arches and hearths shall be not less than 24
inches longer than the fireplace opening. Hearths shall be of
brick, stone, tile, or concrete as may be specified. Wood center-
ing under a trimmer arch shall be removed before plastering
the ceilings beneath.

6. No coal burning heater shall be placed in a fireplace
which does not conform to the foregoing requirements and have
an incombustible mantel.

7. No wooden mantel or other woodwork shall be placed
within 8 inches of the side or within 12 inches of the top
of any open fireplace. No combustible summer piece or fire
board shall be used.

8. Any person or persons, whether owner, builder or me-
chanic, who shall build a chimney or flue in violation of any
requirement of this Ordinance shall be deemed guilty of a mis-
demeanor and shall be fined not less than $10 nor more than

$ for each offense ; and any chimney or flue which is built

in violation of any requirement of this Ordinance shall be im-
mediately demolished or rebuilt. It shall be the duty of the
Building Inspector or other duly authorized official to enforce
this Ordinance.

9. All ordinances or parts of ordinances in conflict with
this Ordinance are hereby repealed.

10. This Ordinance shall take effect upon being approved
by the

14

APPENDIX

This Appendix contains reasons for certain requirements in
the Ordinance, and various suggestions for good practice not
suitable to be included in the Ordinance itself, but which are
thought to be useful information to accompany it. The material
is, therefore, appended for its educational value, and a munici-
pality in adopting the Ordinance can dispose of the Appendix
as it sees fit.

I. Heat Resistance of Brick.

Brick meeting the temperature requirement of Section I,
paragraph 4, of the Ordinance can be obtained in all sections of
the country at a slight cost above that of ordinary brick. In sev-
eral regions the ordinary brick of the market will meet the re-
quirement, and in such places there would be no additional cost.

It is suggested that each manufacturer of flue linings or
heat resisting brick suitable for chimney lining should have tests
made of the softening point of the clays used in the manufacture
of such products. Such tests should be made by a laboratory
of recognized standing, and the test certificate would constitute
the authority for acceptance of the product as fulfilling the re-
quirements, provided suitable identification marks were placed on
the material. This would be a simple method of accomplishing
the object, and the quality of clay from any particular bank is
sufficiently uniform to secure reliable results.

II. Thickness of Exterior Chimney Walls.

For exterior chimneys, or chimneys having any wall exposed
to the weather, it is recommended that all such exposed walls be
not less than 8 inches thick even though lined. This additional
thickness will produce a more uniform temperature in the flue,
thereby greatly improving the draft, which will result in fuel
economy and a lessening of smoke annoyance.

III. Concrete Chimneys.

Pure quartz gravel or other highly silicious gravel con-
cretes are not adapted to withstand high temperatures, there-
fore should not be used where subject to direct attack of heat.

15

APPENDIX

The reinforcement required in concrete chimneys cast as a
unit, or when built of large blocks enclosing more than one flue
is to resist stresses due to temperature variations or unequal
settlement of foundations.

IV. Filling of Hollow Building Tile.

When chimney walls are built of hollow tile as provided
in Section I, paragraph 10, it is recommended that the inner course
of cells next to the flue lining be filled with mortar.

V. Withes.

A withe between at least every second and third flue
in a chimney space is strictly necessary to insure stability of
the chimney. A withe also aids in securing uniform tempera-
ture in a flue, and prevents air leakage, thus promoting good
draft and fuel economy. At the same time it prevents possibility
of a fire in one flue communicating to the others. For these
reasons every flue connected with a fireplace or heating furnace
of any type is required to be separated from other flues by such
withes. The ideal chimney would have all flues separated by
withes. See Plate IV.

VI. Area and Heights of Chimneys

To secure the most satisfactory draft conditions, the area
and height of a chimney should be proportional to the size
and character of heating appliance attached to it. A poor draft
is a great annoyance, and is difficult to remedy after a chimney
is built.

A round flue will give a better draft than a square or other
rectangular shape having the same cross-sectional area. Round
flues are recommended where it is practical to obtain them, but.
when round flue linings are placed inside rectangular chimney
walls, care must be exercised to insure complete filling of the
corner spaces, otherwise there is liable to be air leakage into the
vacant spaces, which injures the draft and increases the fire
hazard.

The following Table gives the approximate area and height
of chimneys recommended by the furnace and boiler manufac-

16

APPENDIX

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17

APPENDIX

turers associations as suitable to produce proper draft for heat-
ing equipment of different kinds and varying sizes when coal
or coke is the fuel used.

The American Institute of Architects and the American
Society of Heating and Ventilating Engineers have withheld
approval of this Table on the ground that it is not yet a suffi-
ciently recognized standard to warrant its being accepted as a
satisfactory guide in all cases. The other endorsers of the
Ordinance have not expressed an opinion on this matter.

VII. Suggestions for Repair of Old Unlined Chimneys.

1. A chimney in any existing building that becomes too
hot to hold the hand against comfortably is dangerous if there
is woodwork touching it. Have it carefully inspected by a re-
liable mason, and apply the protection prescribed by this
Ordinance as far as is possible.

2. The smoke test as described in Section I, paragraph 26, is
strongly recommended as the best method for discovering defects
in chimney walls which always indicate danger. If smoke
escapes through the chimney walls at any place the chimney
should be repointed or rebuilt as conditions may warrant.

3. Where soft coal is used it is often necessary to rebuild
unlined chimney tops every few years, and all unlined chimneys,
irrespective of fuel used, are very liable to become defective
through disintegration of the mortar joints. In order to ascertain
if chimneys need rebuilding, climb to the top and look inside.
If mortar has begun to fall out from between the bricks it will
soon do so all the way through the wall. Take an ice pick, a
table knife, or other sharp implement and try to push it through
the mortar ; if you can do so, rebuild at once as follows :

Tear the chimney down to a point where mortar joints are
solid, but at least 18 inches below the roof, get fire clay flue
lining of the same size as the inside measurement of the
chimney, set it in the top of the flue and build up with good
brick and Portland cement mortar. This will make a solid
chimney through the roof where there is greatest danger, and
is the best that can be done unless the chimney is completely

18

APPENDIX

torn down and rebuilt. Preserve a clear space of at least 1 inch
between the woodwork of the roof and the chimney wall, and
connect the chimney- with the roof by metal flashings. Build to
a height above the roof as specified in Section I, paragraph 11,
of the Ordinance.

VIII. Cleaning Chimney Flues."

'For efficient and safe operation of heating apparatus it is
extremely important that both the flue and the smoke passages
in the heating device be free from soot. When bituminous coal
is used for fuel, soot accumulates quite rapidly and frequent
.cleanings are necessary.

Accumulation of soot in a chimney introduces the risk of a
chimney fire with the consequent danger of sparks being thrown
upon the roof or penetrating cracks in the chimney walls. This
is a very great hazard and is the reason why chimneys should
never be purposely burned out to clean them. The burning out
of a tile lined flue is liable to crack the lining.

A common and efficient method of cleaning a chimney is to
sweep it with a properly weighted bundle of rags or a bush at-
tached to a rope and worked from the top, but because this
operation is troublesome, chimney cleaning is frequently neg-
lected.

Other methods of chimney cleaning recommended as simple
and efficient are as follows:

1. The U. S. Fuel Administration has strongly advocated
the use of salt. The fire should be put in good condition with a
substantial body of hot fuel. Well dried common salt is then
scattered over the incandescent fuel in quantity depending upon
the size of the furnace. For a household furnace, a pound at a
time is ample. The dampers should be kept open to maintain
the furnace temperature until the fumes entirely disappear.
This usually takes about half an hour. The soot is disintegrated
by the action of the salt fumes. Repeat the application as
necessary.

This method is highly endorsed for cleaning boiler tubes
and furnace passages. It does not interfere with the operation
of the plant and neither brickwork nor metal is deteriorated.

19

APPENDIX

It is known that a layer of tarry soot 1/16 inch thick on
boiler tubes or furnace passages will decrease their heating
efficiency 20 per cent, hence the necessity of keeping them clean.
It is claimed that an occasional use of salt as described will keep
both heating apparatus and flue free from soot.

2. An ex-fire chief recommends firing a revolver loaded
with one or two blank cartridges up a chimney flue to remove
soot. He asserts it to be very effective and that no injury to
the flue results. Precaution should be taken to shut off the
flue opening or fireplace with an old blanket or piece of burlap
to prevent the soot flying back into the room when it falls fol-
lowing the shot. This method requires that the fires be ex-
tinguished before it is applied.

3. Scrap zinc thrown on a hot fire is recommended as a
soot remover. The zinc fumes are said to disintegrate the soot.

Zinc compounds are also sold for this purpose, but as several
pounds of these zinc materials are recommended to be used at a
time, they would be somewhat expensive.

IX. Extinguishing Chimney Fires.

A handful or two of powdered sulphur thrown on a fire is
claimed to be effective in extinguishing a soot fire in a chimney. It
produces sulphur dioxide which extracts the oxygen from the
air supply and so prevents combustion.

A few pounds of salt thrown in the flue at the top is an old
and excellent remedy for a soot fire. Even a pail of sand earth
or ashes is helpful. Such materials, however, should be used
with much care, if at all, when a fireplace connects with the
chimney flue, for they would be liable to scatter the burning soot
into the room where the fireplace is located.

20

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TO— ^ 202 Main Library

LOAN PERIOD I
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ALL BOOKS MAY BE RECALLED AFTER 7 _,„.-„„

1 -month loans may oe renewed by calling 642-3405

i-year loans may be recharged by bringing the books to the Circulation Desk
Renewals and recharges may be made 4 clays prior to due date

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UNIVERSITY OF CALIFORNIA, BERKELEY
FORM NO. DD6, 60m, I /83 BERKELEY, CA 94720

GENERAL LIBRARY - U.C. BERKELEY

BDOOflOS75M

465855

UNIVERSITY OF CALIFORNIA LIBRARY