EQUIPMENT PESTICIDE TRAINING MANUAL
STATE DOCUMENTS COLLEC7.0M
FEB b *368
MONTANA STA'E UB.T/.nY
1515 E. 6th AVE^
HELENA, MONTANA 5952C
r> s — s
STATE OF MONTANA
DEPARTMENT OF AGRICULTURE
ENVIRONMENTAL MANAGEMENT DIVISION
HELENA, MONTANA
JANUARY, 1986
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I
PREFACE
This manual contains a basic description of the types of ground
and aerial pesticide application equipment, its maintenance, safe
use, and calibration. The manual is intended as a study guide
for all applicators being licensed to apply restricted use
pesticides. It can also serve as a reference for future
maintenance, use, and choice of appropriate equipment.
The selection of proper application equipment, its maintenance
and safe use, and calibration are essential for obtaining
effective results from pesticide applications. This manual will
illustrate, for example, the types of equipment appropriate for
various crops and pests. It will outline the types of equipment
components that are most suitable for the various mixes or
formulations of pesticides. These and other topics may assist
many applicators in efficiently using their equipment.
Hopefully, applicators will continue to follow the suggestions of
this manual. They will improve pest control and protect
environmental and human health.
To simplify information, trade named products and equipment have
been mentioned. No endorsement is intended, nor is criticism
implied of similar products or equipment which are not mentioned.
We wish to acknowledge the help of personnel of the Environmental
Management Division, Montana Department of Agriculture, in
preparing this manual.
1
TABLE OF CONTENTS
Page
Pretace i
CHAPTER 1. PESTICIDE FORMULATIONS AND COMPATIBILITY 1
A. Formulations 1
B. Accessory Materials and Adjuvants.,'. 3
C. Compatibility of Pesticides 4
D. Synergism ; 6
CHAPTER II. GROUND EQUIPMENT, ACCESSORIES, AND MAINTENANCE 7
A. Types of Ground Equipment 7
B. Accessory Equipment..... 10
CHAPTER III. MAINTENANCE OF GROUND EQUIPMENT 24
A. Inspection and Filling 24
B. Cleaning the Sprayer '. 24
CHAPTER IV. GROUND EQUIPMENT CALIBRATION 2 7
A. Variables Affecting Application Rates 27
B. Calibration 28
CHAPTER V. AERIAL EQUIPMENT AND CALIBRATION 37
A. Types of Aircraft 37
B. Drift 37
C. Viscosity Modifiers 40
D. Equipment for Dispersing Pesticides 40
E. Safety and Maintenance 4 4
F. ULV Application 44
G. Calibration 45
APPENDIX Conversion Factors for Units of Measurement 48
11
CHAPTER I
PESTICIDE FORMULATIONS AND COMPATIBILITY
The choice of a pesticide depends, in part, upon the equipment
the applicator has available. Many applicators own boom sprayers
that are sufficient for a variety of liquid pesticides. Many
products such as dry dusts or liquids intended for atomizers need
specialized equipment. Pesticide selection depends upon a number
of principles; one of these is the formulation or the manner in
which the active ingredient, carrier, and special additives are
mixed. The following chapter is a discussion of these pesticide
components .
A. Formulations
Formulations affect the physical state of the pesticide and the
method of application. Following are some common types of
formulations :
1. Dusts are a mixture of the active ingredient with a
carrier such as talc or clay. Fine particle size makes dust
formulations susceptible to drift. Forced air is often used
to deliver dusts. Herbicides seldom are marketed as dusts
because of associated drift problems.
2. Granular formulations are formed by impregnating an
active ingredient on a small particle (1-2 mm. diameter) of
carrier. Granules are used to penetrate dense foliage.
Granules usually are marketed ready to use. Where residual
action is required, they may provide slow release of
pesticide .
3. Wettable powders are dry pesticides that have been
attached to a dry carrier such as clay. A v/etting agent is
usually added and the powder is mixed with water to form a
suspension that must be kept agitated in the spray tank. A
sticker or adhesive agent is usually added to promote
adhesion .
4 . Emulsifiable concentrates contain a pesticide and an
emulsifying agent in a solvent such as xylene or petroleum
fractions. These are diluted with water to form an emulsion
that can be applied as a spray.
Emulsions can occur in two ways depending on the mixing:
a. Normal emulsions consist of the oil phase or
concentrate dispersed in water.
b. Invert emulsions are prepared by adding the oil
phase to the water phase. The oil phase then becomes
continuous, surrounds cells of water, and evaporation
is reduced.
1
Emulsions usually form with very little agitation and should
be stable for about a day.
5. Oil Solutions - Most pesticides are not soluble in
water so petroleum oils are commonly used as a solvent.
Examples of oil solvents are deodorized kerosene, fuel oil,
and xylene. Oil solutions are generally avoided for use on
plants; however, they can be sprayed in mist blowers where
the oil evaporates before reaching the plants.
6 . Concentrates or Ultra Low Volume (ULV) formulations are
applied with ULV applicators. The active ingredient is
applied in its concentrated form. Evaporation is reduced
because water is absent. ULV droplets are of greater
density than those in water based sprays, thus increasing
their rate of fall. Because less volume of formulation is
applied per acre, more acreage can be treated before
reloading .
7. Baits consist of the active ingredient mixed with a
solid carrier that is attractive to the pest, such as rolled
oats or sugar. Rodenticides are usually dispensed in bait
form.
8. Flowables or suspensions are liquid or viscous
concentrates of a suspendible pesticide in water as minute
solid particles. Flowables usually require further dilution
and must be kept agitated.
9. Fumigants are usually liquids that, when exposed to
warm air or released from pressure, form a toxic gas, fume,
or vapor. They are usually used in air tight enclosures or
confined spaces such as grain bins, buildings, greenhouses,
or rodent burrows. Some soil fumigants are produced in
granular form.
10. Aerosols consist of small particles, about 10 microns,
suspended in air and are often used in adult mosquito
control and in structural pest control. Because of a
tendency to drift, they are not useful in most agricultural
situations. Aerosols are produced by the following methods:
a. forcing a liquid under pressure through atomizing
nozzles ,
b. release of liquified gas through expansion chamber
or capillary nozzles,
c. steam or air atomization of a liquid,
d. heat vaporization,
e. spinning discs or rotors.
2
11. Fogs and mists are produced by methods similar to
aerosols but particles are smaller, about one-tenth micron.
They have been used in mosquito control and in treating
confined spaces.
12. Capsules made of materials such as gelatin may confine
the pesticide and dissolve or disintegrate to release the
pesticide .
B . Accessory Materials and Adjuvants
The mode of action of pesticides may be improved by the addition
of accessory materials and adjuvants. Accessory materials
include diluents, carriers, solvents, and adjuvants.
1 . Carriers are added to concentrates and give the
formulation "body" and "surface" adequate for application.
Carriers are often inert ingredients such as water in
flowables or talc in dusts.
2. Diluents are liquids added to reduce the concentration
to the appropriate application rate.
3. Solvents are used to dissolve a formulation into a
carrier or diluent; they are usually utilized when the
formulations are solid or viscous. Diluents and carriers
may also act as solvents.
4. Adjuvants are added to pesticide formulations to
improve their mode of action. These substances may increase
spreading properties, assist emulsification, enforce
toxicity, promote penetration of plant parts, reduce
interfacial tensions, and perform other related functions.
Adjuvants are either incorporated into the pesticide
formulation at the time of manufacture or added by the
applicator under certain restricted conditions. The
addition of proper adjuvants can result in a more effective
and economical pesticide. Following is a description of the
various types of adjuvants and their properties.
a. Surfactants or Spreading Agents allow the
pesticide to "spread out" over treated surfaces and
assist in "wetting" dusty, waxy, or greasy surfaces.
These materials also reduce surface tension allowing
the pesticide to make contact with a solid surface and
lend to penetration of the chemical into plants and
animals. Caution should be exercised because
surfactants may destroy protective wax layers on leaves
or fruits and damage the crop.
b. Emulsifiers or Emulsifying Agents are utilized to
maintain the stability of an emulsion. Stability of a
mixture relates to the length of time it stays mixed.
Oil and water mixtures separate readily; the addition
3
of an emulsifier stabilizes the mixture because it
occupies the space between the oil and water. Soaps
and detergents may serve as emulsifiers. Detergents
are usually preferred because soaps form alkaline
solutions with water.
c. Sticking or Thickening Agents improve spray
adherence to surfaces such as leaves. Thickening
agents increase viscosity and increase spray adherence
to leaves thus reducing spray bounce and run-off during
spraying. The term "spreader-sticker" is commonly
utilized today. Sticking agents are usually added to
formulations to reduce the amount of run-off from
surfaces caused by spreading or wetting agents.
Other types of adjuvants include antisticking agents,
penetration agents, dispersing agents, bridging agents, and
activators or synergists.
C . Compatibility of Pesticides
Application of one pesticide at a time has been the common
agricultural practice. Today, because of the high cost of
application, pesticide applicators have begun mixing pesticides
in an attempt to control several pests with a single application.
When two or more pesticides can be mixed together without any
adverse changes in action or structure, they are compatible .
Certain pesticides, however, are incompatible because adverse
changes occur between the active ingredients or formulations.
Several reasons for incompatibility are given below:
1. Physical incompatibility is difficult to evaluate and
is often caused by the additives rather than the pesticides
being incompatible. The results of physical compatibilities
are varied. A common one is the formation of precipitates
in the mixture that can plug screens and nozzles. Another
occurs when the activity of an emulsifier is stopped.
Mixtures may then separate or form large droplets within the
tank .
2. Chemical incompatibility occurs when chemical reactions
occur that destroy the effectiveness of one or more
pesticides. For example, fungicides or adjuvants that are
strongly alkaline may decompose synthetic organic
insecticides and change their activity. Precipitates may
occur that will plug screens and spray nozzles.
Formulations may be altered so that they no longer contact
or adhere to the target. Reactions may occur which cause
the formulation to be toxic to plants or phytotoxic.
Chemical incompatibilities cannot always be recognized in
the spray tank.
4
3. Timing incompatibility - Pesticides must be applied at
the most susceptible development stage of the pest for
greatest effectiveness. When spraying a mixture of two or
more chemicals, it may be difficult to time the application
to the most susceptible stage of the various pests.
4. Water incompatibility - Water is the most common
carrier for pesticides. Water hardness (high amounts of
calcium) may alter the formulation of a pesticide, making
application difficult or less effective. Generally, waters
that are "soft" should be utilized as carriers. Applicators
should determine the hardness of water in their area prior
to mixing one or more pesticides. Water may be softened
chemically, thus preventing problems in mixing pesticides.
Points to Consider When Mixing Chemicals
(1) The compatibility of the various chemicals must be
known before the materials are combined.
(2) As a general rule, do not mix herbicides with
insecticides .
(3) Follow all label directions carefully. The use of tank
mixes not specifically stated on the label is discouraged by
most manufacturers.
(4) Combinations containing lime or having a high
alkalinity are harmful to synthetic organic chemicals. Most
organophosphates and carbamates are subject to alkaline
decomposition .
(5) The use of oils and petroleum solvents in combination
with organic chemicals may increase phytotoxicity.
(6) Most of the dinitro miticides may become phytotoxic if
mixed with oil.
(7) Organophosphates combined with dinitros may cause
burning of foliage.
(8) Consult all available sources before utilizing
combinations .
Compatibilities of various chemicals can be checked by
referring to a compatibility chart in the Farm Chemicals
Handbook. Some chemical companies also print compatibility
charts .
Caution is imperative to any applicators wishing to check unknown
compatibilities. Chemical or phytotoxic compatibilities cannot
be observed. Keeping the above eight points in mind, physical
compatibilities can be checked by mixing small amounts of
chemicals in jars. These mixtures should be observed initially
5
and after one hour for any adverse changes such as settling,
precipitates, gumminess, separation, etc.
Pesticide labels will often list compatible and incompatible
chemicals. If not, it is permissible by the Federal Insecticide,
Fungicide, and Rodenticide Act to mix pesticides or pesticides
and fertilizers. This should be done with caution. Contact the
Montana Department of Agriculture Pesticide Specialist in your
area for assistance.
D. Synergism
When the effect of two combined chemicals in greater than the
effect of either compound alone, the result is called synergism.
Utilizing two products with synergistic qualities may increase
the effectiveness of the treatment; however, the use of a
synergized compound may also increase the problem of toxicity to
mammals .
6
CHAPTER II
GROUND EQUIPMENT, ACCESSORIES, AND MAINTENANCE
A. Types of Ground Equipment
The five basic classes of ground application equipment include
hydraulic sprayers, air sprayers, loggers and aerosol generators,
power dusters, and hand held equipment.
1. In hydraulic sprayers, pesticide is delivered under
pressure by a pump to one or more nozzles. The kind of
nozzle regulates droplet size and spray pattern. The
components of a typical low-pressure, low-volume hydraulic
sprayer are shown in figure 1. Hydraulic sprayers are of 4
basic types:
a. Multiple-purpose sprayers provide versatility for
a variety of farm problems. Spray pressure is
adjustable and can provide, for example, 40 pounds for
weeds or 400 pounds or more for spraying fruit trees.
Tank size ranges from 50 to 200 gallons. Sprayers are
skid or wheel mounted and powered by auxilary engines
or a power take-off. Spray is dispensed through a hand
gun or field boom.
b. Small general use sprayers are useful for small
spraying jobs that are too large for hand equipment.
They are useful in greenhouses, large gardens, and golf
courses. Tank capacities vary up to 25 gallons. Power
is from a 1/2 to 2 horsepower engine that provides a
wide range of pressures (50-500) psi) . Spray is
dispensed through a hand gun or short boom. Sprayers
are usually mounted on a hand-operated cart; some can
be attached to a garden tractor.
c. Low-pressure, low-volume sprayers are commonly
used in Montana crops. They can be mounted directly on
equipment or are equipped with wheels. Sprayer tanks
hold up to 250 gallons. Power is usually from the
tractor pto but may be supplied by an auxiliary engine.
Operating pressure is up to 100 pounds and spray is
dispensed through a field boom. Some sprayers, the
Spray Coupe for example, are self-propelled.
d. High-pressure, high-volume sprayers are used by
fruit growers and truck farmers in order to obtain good
penetration and coverage in tall growing trees and
dense crop growths. These sprayers are essentially the
same as multiple-purpose sprayers except that larger
engines provide up to 1000 pounds of pressure. Tank
sizes are also larger and range up to 600 gallons.
7
Figure 1. Components of a Boom Type Field Sprayer with
Hydraulic Agitation.
8
2. Air sprayers (also known as ultra-low volume,
concentrate blower, air-blast, and air-mist sprayers) are
used for spraying orchards, large shade trees, and field
crops. Pesticides are applied in concentrated form using
relatively small volumes of water in contrast to hydraulic
sprayers. Labor involved in loading is saved and pesticide
runoff is reduced. A low-volume pump delivers the liquid
spray under low pressure to the fan where it is discharged
into an air stream in small droplets by a group of nozzles
or shear plates. Pump pressures range from 50 to 400 p.s.i.
and fans deliver from 5000 to 25,000 c.f.m. or air
velocities of 100 to 150 m.p.h.
3. Foqqers or Aerosol Generators are designed primarily
for control of mosquitoes and flies in large buildings,
parks, resorts, or communities. These machines disperse
fine particles of pesticides into air, as fogs or mists,
where they remain for a considerable time period. Fogs and
aerosols are produced by either thermal (heat) or mechanical
methods or a combination of both.
Air currents assist in moving the pesticide to the target
area, taking advantage of the principle of air inversions.
Applications are usually made at night when wind,
temperatures and humidity conditions are optimum.
Aerosol equipment is not practical for most agricultural
pesticide applications (especially herbicides) because of
their tendency to create drift problems.
4. Power dusters are powered by engine or power take-offs.
Like air blast sprayers, dusters also utilize air streams
from a centrifugal fan to carry the pesticide to the target
area. They may have single or multiple outlets. Dusters
may be impractical for application of some pesticides,
especially herbicides, because of drift hazard.
5. Hand application equipment is designed primarily for
application of pesticides in small areas like homes,
gardens, businesses, or yards. This type of equipment
includes hand pump atomizers, aerosol dispensers, compressed
air sprayers, knapsack sprayers and dusters.
a. The hand pump atomizer uses a hand operated pump
to force an air stream over the tip of a siphon tube.
Pesticide is sucked from the tube and atomized in the
air stream. The intermittent type sprayer produces a
spray only on the forward motion of the pump. The
continuous sprayer delivers a continuous spray because
pressure is produced in the tank. These sprayers are
commonly used to control flying insects in the home.
They have nearly been replaced now by aerosol
dispensers .
9
b. Aerosol dispensers or "bug bombs" are probably the
most common type of applicator. The pesticide and a
propellant, usually freon, are forced, under pressure,
through an atomizing nozzle. Many household pest
sprays are dispensed in aerosol bug bombs.
c. Compressed air sprayers are designed to hold 1 to
3 gallons in the tank. A hand pump is used to
pressurize the tank and to deliver the pesticide, under
pressure, to the nozzle. Spray patterns and droplet
size can be regulated by nozzle type. Solutions,
emulsions, or suspensions of pesticides can be utilized
at pressure of 30 to 50 psi. The use of CO„ cylinders
in place of the hand pump may be utilized to achieve
the correct pressure.
d. Knapsack hand sprayers are carried on the back and
usually have a capacity of 5 gallons. A hand operated
piston or diaphragm pump provide the pressure (30 to
100 psi) to expel the pesticide.
e. Duster hand sprayers range from small
self-contained units to those mounted in wheelbarrows.
Air velocity for dispensing the dust is created by a
plunger, hand crank, or belt attached to a fan or
blower .
Additional types of hand sprayers include bucket, barrel,
and wheelbarrow sprayers utilized for spraying larger areas
or trees and hose sprayers in which a jar container is
attached to a garden hose.
B . Accessory Equipment
Sprayer accessory equipment consists of nozzles, pumps, pressure
regulators, strainers and screens, nozzle check valves,
agitators, pressure gauges, and tanks,
1. Nozzles are manufactured with a variety of functions
and for many conditions. Performance tables are available
from most dealers.
Types of Nozzles
There are many types of nozzles used in spraying. Each have
different purposes and differ in such factors as spray
pattern, flow rate, and average droplet size. Some of the
common nozzles are illustrated in Figure 2 and discussed
below.
a. Flat Fan Nozzles produce a fan-shaped spray
pattern with tapered ends and a fan angle of 65 to 80
degrees. The tapered ends permit overlapping of spray
patterns to assure uniform coverage. Adjacent spray
10
patterns should not be allowed to impinge on each other
because it will destroy the uniformity of coverage.
Each spray nozzle should be rotated approximately 12 -
15 degrees from the line of the boom so the patterns
are slightly offset (Figure 3) . Flat spray nozzles are
generally used in surface spraying in agriculture and
many other types of pest control. They do not provide
very good foliar penetration.
b. Even Fan Nozzles deliver a uniform fan-shaped
pattern with a fan angle of 80 degrees. Edges of the
pattern do not taper as in flat spray nozzles. These
nozzles are used for band or row application,
pre-emergence or early post-emergence. Broadcast
applications are not recommended because of the
difficulty of preventing overlap (overdose) or gape
between spray patterns. Like flat spray nozzles, they
do not provide good foliar penetration.
c. Flooding Fan Nozzles provide a flat spray pattern
with a wide spray angle (100 - 145 degrees). These
nozzles produce a wide spray pattern and large droplets
at low pressure. Because of the nozzles' wide spray
angle, they can be widely spaced on the boom and
carried close to the ground to reduce drift. If these
nozzles are angled 10 to 15 degrees in the direction of
travel, drift can be further reduced. These nozzles
can be used in general broadcast application of
fertilizers, herbicides, and defoliants. They are
commonly used for applying materials which require soil
incorporation. They do not provide good foliar
penetration.
d. Cone Spray (Solid or Hollow) Nozzles deliver a
cone shaped spray pattern which may be solid or hollow
depending on the nozzle's design. These nozzles are
generally used at high pressure to deliver insecticides
and fungicides to row crops and provide good foliar
penetration. Because these nozzles produce smaller
droplets, the potential for drift is increased.
e. Off Center Flat Fan Nozzles produce a one-sided
flat spray pattern which is used on the end of a boom
to extend coverage by 5 feet.
f. Twin Orifice Flat Fan Nozzles are used to apply
herbicides between row crops. Nozzles produce a wide,
fan-shaped pattern which can be applied close to ground
level .
g. Multiple-Orifice Nozzles or clusters of nozzles
are used in place of a boom and spray a swath 30 to 50
feet wide. These nozzles are used to spray roadsides.
11
Types of Ifozzles
Figure 2.
Solid
Stream
Even
Fan
Hollav
Gone
Solid
Cone
's »r'» t.' 1 ■
Flat Fan
Tapered Edge
Off Center
Flat Fan
12
Flooding
Figure 3. Section of a field boom showing proper alignment
of fan nozzles to provide spray overlap.
13
ditchbanks, or other places where a boom or field
sprayer is not satisfactory. The spray pattern is
easily affected by wind conditions which may cause poor
coverage and pesticide drift.
h. Low-Pressure and Reduced Pressure Nozzles are
designed to reduce the potential for spray drift by
producing larger droplets.
(1) Low-Pressure Nozzles operate in the 10 to 30
psi range and provide the same spray angle and
flow rate as a conventional nozzle at 40 psi.
Because the nozzles operate at lower pressures,
they wear longer and there is less stress on other
sprayer components.
(2) Reduced Pressure Nozzles operate at the
standard pressures but, because of their design,
there is a pressure drop within the nozzle. The
net result is that fewer droplets smaller than 100
micrometers are produced. Nozzles of this type
work best for applying high volume, for applying
materials that require soil incorporation, or
where fine coverage is not necessary. These
nozzles may not be adequate with low volume
application or foliar application where complete
coverage is required.
i* Straight Stream Nozzles are simple nozzles with a
center orifice that produces a straight stream of
liquid. These nozzles are used for subsurface
application of liquid fertilizers, soil fumigants, and
some aquatic herbicides, and for crack and crevice
treatment in structural pest control.
Nozzle Materials
Nozzle tips are made from a variety of materials varying in
cost and resistance to wear and corrosion. The following
are some common materials listed in order of resistance.
Nylon or Plastic is suitable for most pesticides,
resists corrosion and wear, but may swell when exposed
to some solvents .
b. Brass resists corrosion but wears quickly from
abrasive materials; brass nozzles are for limited or
short term use and are inexpensive.
c. Aluminum is not recommended for abrasive materials
such as wettable powders and can be corroded by some
fertilizers but is inexpensive.
14
d. Stainless Steel is suitable for all formulations,
all purpose use; resists corrosion and wear and is
expensive .
e. Tungsten Carbide Steel and Ceramic nozzles are
extremely resistant to corrosion and wear and are
expensive .
Nozzle Numbering and Coding
Unfortunately there is not a uniform system of nozzle
numbering. Each manufacturer will indicate flow rate, spray
angle, and other information by number and letter codes.
Flow rates are measured in gallons per minute (GPM) at a
standard pressure of 40 psi using water. For further
reference, nozzle manufacturers' catalogs and bulletins
provide an excellent source of information.
Disc for Handguns
The spray or cap number represents the diameter of the
orifice in increments of 1/64 of an inch. For example. No.
3 disc has an orifice 3/64 inch in diameter. Larger
orifices deliver coarser droplets at higher rates. To
determine the proper disc size for your operation, consult
manufacturers' charts.
Nozzle Flow Rate or Capacity
The flow rate of a nozzle is increased by larger metering
passages and exit orifices. Flow rate is also affected in
varying degrees by pressure, liquid density, and liquid
viscosity.
a. Flow rate varies in proportion to the square root
of the pressure. As pressure increases, so does
pesticide flow rate.
b. As the pesticide density becomes greater, flow
rate is reduced.
c. Effects of viscosity on flow rate are complex, but
generally, flow rate decreases as liquids become more
viscous .
Many applicators may not be interested in the above factors
but they should be aware of their effects on flow rate.
They illustrate the importance of calibrating when changing
nozzle size, pressure, or spray mixture.
Spray Angle and Pattern
Pressure and liquid viscosity influence spray angle and
pattern:
15
a. Pressure - A minimum pressure is required to
develop a proper spray pattern, usually 10 to 15 psi.
Lower pressures tend to produce a distorted spray
pattern. When pressure is too great, the nozzle will
begin to atomize the spray and the pattern will be
changed. Applicators can make the mistake of operating
at excessive pressures in order to make the spray reach
further. Actually the opposite effect may occur as the
spray atomizes and pattern changes and drift may occur.
A nozzle with a larger orifice should be used.
b. Liquid Viscosity - Viscosity is the only liquid
property that has a significant effect on spray
patterns. An increase in viscosity produces a narrower
pattern and smaller spray angle. At very high
viscosities, the spray may become a straight stream.
Atomization & Droplet Size
The range of droplet size is affected primarily by the
nozzle orifice size and pressure. Each nozzle produces a
variety of droplet sizes, the majority centered around one
size. Droplets are measured in micrometers or microns where
25,400 micrometers equal one inch. VMD or Volume Mean
Diameter is also used as measure of droplet size. VMD is
that droplet diameter whose volume if multiplied by the
number of droplets will equal the total volume of the
sample. To give an idea of droplet sizes, the following
chart is included.
Category Size Range in Micrometers
Droplet size is influenced by:
a. Nozzle rating and design is the primary factor
influencing droplet size. As nozzle capacity and
metering passages increase in size, the average droplet
generally becomes larger. Spray angle ratings also
affect droplet size. Wider spray angles are associated
with finer droplets.
b. Pressure - As pressure increases, more droplets of
a smaller size tend to be produced. A limit is
eventually reached where increasing pressure has little
effect in reducing droplet size.
Fog
Aerosol
Mist
Fine Spray
Coarse Spray
0.1- 50
1.0 - 50
50 - 100
100 - 400
greater than 400
16
c. Liquid Viscosity - As viscosity of a fluid
increases, droplets become coarser. Increases in
pressure will counteract the effects of viscosity.
d. Surface tension - Liquids with a higher surface
tension are more difficult to atomize. The effect of
surface tension is generally minor compared to
viscosity .
2 . Pumps
The sprayer pump is the heart of the system. Pumps vary in
capacity (output), operating speed and pressure, and
resistance to corrosion and wear. Capacity, which is
affected by speed and pressure should be large enough for
high application rates. Pumps should provide for agitation
if the sprayer does not have a mechanical agitator.
Manufacturer's performance tables can assist you in
selecting the proper pump. Some of the commonly used pumps
are :
a. Centrifugal pumps commonly operate from a PTO and
must be operated at high speed (3000 to 6000 rpm) to
obtain adequate capacity. High output occurs at normal
operating pressures (30-90 psi) . They are not
self-priming and must be located below the fluid level
if a priming system is not used. They are resistant to
wear and can pump wettable powders or other abrasives.
In operation, liquid enters at the center of a rotating
impeller with vanes molded in a spiral configuration.
Liquid is forced along the vanes by centrifugal force
and out a discharge hose.
b. Turbine pumps exhibit the same advantages and
disadvantages as centrifugal pumps. The primary
differences are in closer tolerances and additional
fins. The optimum operating speed is 1000 RPM and can
be directly from a 1000 RPM PTO shaft. A step-up drive
is necessary for a 540 RPM PTO shaft. The impeller,
nylon or cast iron, is a construction of many closely
aligned turbine blades. The housing constricts around
the blades at the exit port which forces the liquid
from the pump.
c. Roller pumps are inexpensive, short-life pumps
useful in a variety of situations. Operating pressure
varies from 30 to 200 psi and outputs are up to 50 GPM.
Higher pressures and operating speeds decrease pump
life. These pumps are suitable for wettable powders
but their abrasive nature shortens the pump life. The
number of rollers varies from 4 to 8 depending on pump
capacity. They are constructed of nylon, rubber.
17
teflon or polypropylene plastic. In operation, a
slotted rotor holds cylinder shaped rollers in an
eccentric housing. As the rotor spins, the rol]ers are
held against the housing by centrifugal force. Fluid
is drawn into the entry port and held in the spaces
between the rollers and the housing. At the exit port,
the smaller space between the rotor and housing forces
liquid into the exit port.
d. Piston pumps - Although they may be operated at
low pressure, piston pumps are designed to operate at
high pressures. For most agricultural uses, 500 to 600
psi is normal although some pumps may produce up to
1000 psi. Output is nearly proportional to pump speed
which, depending on the pump design, may vary from 300
to 1800 RPM. Output from piston pumps is low varying
from maximums of 3 GPM to 25 GPM depending on size,
number of pistons, and operating speed. When spraying
with pressures of 100 psi or more, a piston pump will
provide the best long-term reliability. Most high
pressure sprayers designed for such uses as ornamental
tree spraying, livestock spraying or washing equipment
are equipped with piston pumps. Piston pumps are
expensive but well constructed and a long service life
can be expected. They stand up to abrasive materials
and worn parts can be replaced.
Piston pumps are driven by a PTO or auxiliary engine.
An eccentric camshaft m.oves the piston and fluid enters
and is forced from one way valves in the piston
housing. To smooth the pulsating discharge of liquid,
a surge tank or pulsation damper is required.
e. The following three pumps see little current use
on agricultural sprayers.
(1) Gear pumps - These pumps incur a high wear
rate, and cannot be reconditioned, and must be
discarded after they are worn.
(2) Diaphragm pumps - The pumping action in a
diaphragm pump is produced by the movement of a
flexible diaphragm. Liquid is drawn into one
chamber on the downstroke and forced out of
another on the upstroke. The diaphragm is
resistant to wear by abrasives but may be attacked
by certain chemicals.
(3) Flexible Impeller pumps - These pumps have a
series of rubber vanes attached to a rotating hub.
The pump housing squeezes the hub as the rotor
turns forcing the liquid from the exit port.
Since the paddles will not return to the extended
position if the pressure is too high, a pressure
18
Figure 4.
Diagrams of some pumps used in pesticide application
equipment .
A. Roller Pump
B. Centrifugal Pump
C. Gear Pump
D . Diaphragm Pump
E. Piston Pump
E.
19
relief valve is not needed. They are inexpensive
and the rotors are easily replaced. They are not
suitable for abrasives but work well as low
pressure transfer pumps.
3 . Pressure Regulators
a. Pressure Relief Valves maintain a constant
pressure to the nozzles despite variations in engine
speed. This spring loaded valve allows excess fluid to
be bypassed into the tank and, when the boom is shut
off, the entire pump output is routed to the tank.
These valves are used with roller and piston pumps.
b. Unloader Valves are recommended for high pressure
situations as with piston pumps. When pressure becomes
greater than the pressure setting, excess fluid is
rerouted to the tank. Each time the nozzles are shut
off, the unloader valve opens and routes the pesticide
to the tank. Line pressure between the unloader valve
and the nozzle (s) remains at operating pressure
allowing immediate use when spraying is resumed. The
pressure of the liquid flowing through the unloader
valve back to the tank is very low, saving fuel and
pump wear. Some unloader valves, when properly
adjusted, can serve as a partial relief by-pass valve.
c. Throttling Valves (manually controlled) distribute
and/or restrict the excess pump output. By opening or
closing the throttling valve (s) in a spray system,
pressure is decreased or increased. Throttling valves
are used with centrifugal and turbine pumps.
4 . Strainers and Screens
Screens and strainers remove foreign materials that might
clog nozzles, wear pumps, or interfere with valves. Screens
mesh size refers to the number of openings per linear inch.
The higher the mesh size number, the finer the screen.
3. Tank Screens are coarse screens that remove lumps
from unmixed material and other large foreign materials
when the tank is filled.
b* Line Strainers are generally placed between the
tank and the pump. They are an intermediate size,
10-80 mesh, and are necessary to prevent rust, scale,
sand, or other small particles from entering and
damaging the pump.
c. Nozzle Screens fit inside the nozzle body and
provide final screening of the liquid to protect the
nozzle tips from plugging. Screens are commonly made
of stainless steel or brass and have a mesh size
20
smaller than the nozzle aperture. When spraying
wettable powders, slotted strainers are recommended to
prevent the buildup of suspended solids.
Screens and strainers must be cleaned often using a
soft brush or compressed air. Clogged screens will
cause erratic spray patterns, improper metering and
delivery, or complete liquid blockage.
CAUTION: DO NOT CLEAN SCREENS OR NOZZLES WITH YOUR
BREATH. YOU WILL GET PESTICIDE INTO YOUR MOUTH, NOSE,
EYES AND ON YOUR FACE. THESE AREAS ARE HIGHLY RECEP-
TIVE TO PESTICIDE ABSORPTION.
5 . Nozzle Check Valves
When boom control valves or the spray pump are stopped, the
liquid remaining in the boom or hose lines will continue to
drip from the nozzle and may cause crop damage. This
undesirable dripping of spray material can be avoided by the
use of nozzle check valves. When the line pressure drops
below a certain low pressure, the valve automatically shuts
off all flow. The boom remains full, pressurized, and ready
for immediate resumption of spraying.
6 . Agitators
Many pesticide products, particularly wettable powders and
emulsions, require agitation to assure continuous mixing of
the pesticide formulation. Agitation can be accomplished by
manual, mechanical, or hydraulic methods.
a. Manual Agitation by means of continuous shaking is
sufficient for small hand held sprayers but impractical
for large equipment .
b. Mechanical Agitation is provided by a series of
propellers or paddles mounted on a shaft near the
bottom of the tank. Rotation speed is slow (100 to 200
RPM) because excessive agitator speed can cause foaming
in some spray mixtures.
c. Hydraulic Agitation is provided by returning a
portion of the pump output to the tank. One method
discharges the by-pass spray mixture through holes in a
pipe located at the bottom of the tank. A second
method uses agitator nozzles using the Venturi
principle. By-pass liquid flows through the nozzles
drawing additional fluid into the moving stream through
openings in the side of the nozzle. The volume of
liquid for agitation can be increased 2-3 times by
this method.
21
Some sprayers have a by-pass or overflow hose returning
to the tank from which the spray liquid enters as an
unrestricted straight stream. Although this provides
circulation and mixing of the tank's spray mixture, it
is generally not sutficient to maintain an adequate
suspension of the pesticide product.
7 . Pressure Gauges
Pressure gauges should be periodically checked for accuracy
and should register within the range of pressures commonly
used. Properly operating pressure gauges help insure proper
application rates, keep drift to a minimum, and reduce
equipment wear caused by unnecessary high pressures.
It is common for pressure to be lower at the nozzles than
that registered on the gauge. Pesticides moving through
hoses, valves, couplings, and screens encounter resistance
and pressure is lowered. To reduce pressure loss, hoses
should be kept as short and as large in diameter as
possible. Fittings should be kept to a minimum. Lines,
nozzles, and screens should be cleaned often.
8 . Sprayer tanks
Sprayer tanks should have a large opening at the top that is
splash proof and equipped with a coarse screen. The cover
should be vented and sealed against dust. A drain plug
should be located in the tank bottom. Corners should be
round to facilitate agitation and cleaning.
Construction materials vary in durability and ability to
withstand corrosion. The following are some common
materials ;
Galvanized Steel Tanks give reasonable service if
properly cared for but may eventually corrode. They
are suitable for most pesticides but corrosive
fertilizers and pesticides should be avoided. An epoxy
lining will protect steel tanks from corrosion but is
not effective against hydrocarbons such as Lasso or
Ramrod, or volatile chemicals under pressure.
b. Polyethylene Tanks are lightweight and resistant
to corrosive chemicals except for ammonium phosphate
solutions and some liquid fertilizers. Polyethylene
tanks must be replaced if cracked, broken or punctured.
Polyethylene breaks down under ultra-violet light and
should be kept covered when not in use.
c. Aluminum Tanks resist corrosion by most chemicals.
They should not be used with solutions containing
phosphoric acid.
22
d. Fiberglass Tanks are widely used on agricultural
sprayers and are resistant to most chemicals but may be
affected by some solvents. Fiberglass is a lightweight
but durable material that can be repaired if cracked or
broken .
e. Stainless Steel is the highest quality material
for spray tanks. It is strong, durable and resistant
to corrosion by any pesticide or fertilizer. It is
recommended for equipment with a high annual use.
The capacity of the tank will depend upon the size of fields
to be sprayed, application rate, boom size, and soil
conditions. Excessively large tanks require expensive
supports and may compact soil or leave ruts.
23
CHAPTER III
MAINTENANCE OF GROUND EQUIPMENT
Care and maintenance of equipment will give the best results from
your applications and insure the safe use of pesticides.
Improperly maintained sprayers can result in:
Costly repairs
Improper application rates
Pesticide spills
Other pesticide accidents
Down time
Most dealers provide information and manuals for the care of
their equipment but the following chapter gives a brief summary
on equipment care.
A. Inspection and Filling
Before use, examine the sprayer carefully for worn parts. Are
the hoses cracked and leaking? Examine the suction hose
carefully; any leaks will seriously interfere with the pump
operation. Examine the boom struts carefully and adjust the boom
to the proper height. Clean all components carefully and pay
attention to screens, filters, hoses, and nozzles. Any dirt in
these parts will interfere with application rates.
Mix chemicals using only clean water. Dirt will plug screens and
damage the pump. Water from a ditch or reservoir should be
strained .
B . Cleaning the Sprayer
Rinsing the sprayer after use will reduce corrosion and prevent
contamination of the next spray and accumulations on sprayer
parts. Several rinsing solutions can be used depending on the
carrier ;
1) Water and ammonia
2) Water and soap or detergent
3) Water and lye (lye is corrosive to aluminum)
4) Solvents
Choose cleaning areas with care so that pesticides are not rinsed
onto lawns, children's play areas, or drinking water. Rinse your
tanks in areas where humans, animals, or crops will not be
exposed. Pesticides should not be flushed into sewage systems
without first contacting the Department of Health and
Environmental Sciences or the Montana Department of Agriculture,
Environmental Management Division.
24
The following is a suggested procedure for cleaning equipment
prior to storage at the end of the season:
Step 1. Hose down the inside of tank completely, fill to
half full and flush the system by operating the sprayer.
Step 2. Repeat Step 1.
Step 3. Remove nozzle tips and screens and clean them using a
soft brush and kerosene or detergent water.
Step 4. Fill the tank full and add 1 pound of detergent
for every 50 gallons of water. Circulate through the bypass
pressure regulator and jet agitator for 30 minutes. Flush
solution through the nozzles.
Sprayers that have contained 2,4-D or organophosphate
insecticides should be cleaned by the following procedure
prior to Step 5:
replace the screens and nozzle tips,
fill tank half full of water, add 1 pint of ammonia for
every 25 gallons of water,
circulate solution for about 5 minutes, then discharge
a small amount of solution through nozzles,
keep remaining solution in sprayer at least 4 hours,
preferably over night, and
flush remaining solution through the nozzles.
Step 5. Fill the tank half full of clean water, hose down
the outside and inside, then flush through the nozzles.
Step 6. Remove tips, discs, strainers, and screens and
store in light oil. Store sprayer in a clean, dry
structure. If the pump cannot be drained completely, store
where it cannot freeze. Oil films should be applied to some
types of tanks and possibly the pumps to prevent rusting.
Other preventative measures include:
1) Overhaul pumps yearly during the winter.
2) Protect steel tanks with a light coat of oil or
kerosene .
3) Oil or paint coats inside the tank should be those
approved for such use.
4) Avoid leaving pesticides in the tank for extended
periods of time.
25
5) Hoses used for chemicals can never be decontaminated
don't use them for drinking water.
6) Caustic soda (lye) is corrosive to aluminum parts so
should not be used as a rinse in aluminum tanks.
7) Don't start a pump against pressure; use the proper
relief valves.
8) Always consult the manufacturer's recommendations.
26
CHAPTER IV
GROUND EQUIPMENT CALIBRATION
Application at the proper rate prevents contamination of the
environment and crop damage, and insures efficient pest control.
Correct application rates depend upon properly calibrated and
functioning sprayers and correctly diluted pesticides. For
proper dilution ratios and application rates, always refer to the
pesticide label.
A . Variables Affecting Application Rates
Sprayer speed, pressure, nozzle openings and spacing, and the
viscosity of the spray material affect application rate.
1 . Speed
The ground speed of the sprayer should be determined and
held constant when calibrating output. Best results occur
at three to five miles per hour. Field speed should be
identical to speed during calibration.
How to Determine Speed In Miles Per Hour;
Step 1. Set 2 markers in the field 88 feet apart (88 feet
is 1/60 of a mile) .
Step 2. Select gear and throttle settings on your
equipment .
Step 3. From a running start, check the time in seconds
required to drive the 88 feet.
Step 4. Divide 60 by the time in seconds required to drive
the 88 feet. This will be your field speed in M.P.H.
Example ; If it takes 15 seconds to drive 88 feet, then the
field speed is 60 - 15 = 4 miles per hour.
Table 1 will help you determine ground speed quickly for
measured courses of 100, 200 or 300 feet. Determine the
time in seconds required to drive the measured course then
refer to columns on the left to find miles per hour or feet
per minute.
2 . Pressures
The flow rate of pesticide relates directly to pressure.
Raising the pressure increases the number of gallons applied
per acre. Pressure is regulated on most sprayers by a
pressure regulator or relief-bypass valve.
27
Table 1. GROUND SPEED CONVERSIONS
Miles per
Hour
Feet per
Minute
Time Required in
To Travel
100' 200'
Seconds
300'
1
88
68
137
205
1.5
132
45
91
136
2
176
34
68
102
2.5
220
27
54
81
3
264
23
46
68
3.5
308
20
40
60
4
352
17
34
51
4.5
396
15
30
45
5
440
13.6
27
41
6
528
11.3
23
34
7
618
9.7
20
29
8
704
8.5
17
26
3 . Nozzle Openings
The nozzle opening determines rate of application when
pressure is constant. The larger the opening, the greater
the amount of spray material applied.
4 . Nozzle Spacing
Most sprayers have fixed nozzle spacing. If nozzles are
adjustable, moving them closer together will increase the
amount of chemical applied per acre.
5 . Nozzle Wear
Nozzle wear results in larger nozzle orifices and higher
application rates. Sprayers cannot be accurately calibrated
if nozzles are worn.
6 . Viscosity
Sprayers are usually calibrated with water. If the
viscosity of the spray material is considerably different
than water, calibrate with the liquid that will be used in
spraying. Generally, wettable powder solutions have a
higher viscosity than water; oil base solutions have a lower
viscosity .
B . Calibration
The following section gives some methods to use in calibrating
your sprayer. Prior to calibrating, follow pre-spraying
maintenance guidelines in Chapter IV and replace any worn
28
nozzles. Immediately prior to calibration, make sure the pump
and lines are full to the shut-off valve.
Sprayer calibration essentially involves determining at what rate
your sprayer operates at a given speed and pressure. This figure
is used to calculate the acreage that can be sprayed with one
tank. The proper amount of pesticide can then be added to each
tank to achieve the recommended application rate.
1. Broadcast Spraying - The following three methods apply
to broadcast sprayers, i.e. booms, blowers, and loggers:
a. Calibration Jar Method - Precalibrated jars can be
obtained commercially. Follow instructions that come
with the jar. Lay out a short, measured course (to
determine acreage covered) , attach the jar under one of
the nozzles, and drive the course at a certain speed
and pressure. The application rate in gallons per acre
can be read directly from the jar. Be accurate in your
speed and pressure measurements and in your jar
readings .
Applicators may also calibrate their sprayer utilizing
a regular quart jar and Table 2. Remember that a quart
jar must be filled and then the distance measured.
b . Sprayer Volume Method
Step 1. Fill the tank to a known level with the
calibration fluid. Select an area for a tank run which
is similar to the area to be treated. Accurately
measure off 1/8 mile (40 rods or 660 feet) . Spray the
test run at the speed and spray pressure to be used
when spraying.
Step 2. Return to level ground and refill the tank to
the starting level, measuring the amount of water (or
spray solution) used.
Step 3 . Calculate the sprayer rate (GPA) by the
following formula:
Gallons Per Acre = gallons water added x 66
swath width (feet)
Step 4 . To determine the number of acres that can be
sprayed with one tankful, divide the size of the tank
(gallons) by the sprayer rate (GPA) .
Step 5. Determine the amount of pesticide to be added
to the tank by multiplying the acres one tank will
spray by the recommended label rate per acre.
29
zzil
acii
nchi
6
8
10
12
14
16
18
20*
21
22
24
30
36
42
48
Table 2.
Distance
Required
Nozzle
to Catch
at Various
One Quart
Rates of
per
Application
5 gal
per
acre
7_ gal
per
acre
10 gal
per
acre
12 gal
per
acre
15 gal
per
acre
20 gal
per
acre
25 gal
per
acre
35 gal
per
acre
4356
2904
2178
1742
1452
1089
871
623
3265
2180
1633
1305
1089
816
652
466
2610
1744
1305
1045
871
652
522
373
2178
1452
1089
871
726
544
435
311
1868
1245
934
747
624
624
374
267
1633
1089
816
652
544
407
326
233
1452
968
726
580
484
363
290
207
1036
871
653
522
435* *
327
261
187
1245
830
622
498
415
311
249
178
1188
792
594
475
396
297
238
170
1089
726
545
436
363
373
218
156
871
581
436
348
290
218
174
124
226
484
363
290
242
182
145
104
622
415
311
249
207
156
124
89
545
363
272
218
182
136
109
78
CAUTION; Check output of all nozzles, and select an average
nozzle for calibration.
NOTE: When nozzle spacing is not uniform or when more
than one nozzle is used per row, use the average
spacing. If three nozzles are used per row and
the row spacing is 42 inches, the nozzle spacing
would be 42 - 3, or 14 inches.
*EXAMPLE: Using a boom sprayer with nozzles spaced 20 inches
apart on the boom, if a quart of the spray
material (or water) is collected from one nozzle
while the sprayer is traveling a distance of 435
feet, the rate of application is 15 gallons per
acre. The speed is accounted for in the distance.
30
step 6. If the recommended rate of chemical is given
in pounds per acre, the liquid quantity (GPA) can be
determined. Divide the pounds of chemical needed per
tankful by the number of pounds in one gallon or the
acid equivalent of the chemical.
c . Nozzle Volume Method
Step 1. Select container to be used for collecting
nozzle spray discharge. Standard measuring containers,
calibrated in cups or ounces, are suitable for
determining the amount of material collected. Some
companies offer calibrated containers for measuring
nozzle discharge. Some farmers use plastic bags for
collecting the spray samples.
Step 2. In the field to be sprayed, set 2 stakes 40
rods or 660 feet apart.
Step 3. Fill the tank 1/2 or 3/4 full with clear
water .
Step 4. Drive the sprayer unit to a position 20 to 30
feet from the course and attach containers to the
nozzles .
Step 5. Drive toward the course at the proper speed
and turn the sprayer on as the first stake is passed.
Proceed toward the second stake maintaining uniform
speed and pressure throughout the course.
Step 6. When the boom or nozzles reach the second
stake, close the cut-off valve or turn the sprayer
"off".
Step 7. Accurately measure the water collected from
one nozzle or the average of several nozzles. Multiply
by the number of nozzles on the boom for total
discharge .
Step 8 . Calculate the sprayer rate (GPA) by
multiplying the number of gallons used by the factor 66
and divide by the width of the spray swath (feet) .
Step 9. Determine the number of acres which can be
sprayed with one tankful of spray. This is found by
dividing the tank size (gallons) by the sprayer rate
(GPA) .
Step 10. Determine the amount of chemical to be added
to the tank by multiplying the acres one tank will
spray by the recommended label rate per acre.
31
step 11. If the recommended rate is given in pounds
per acre, the liquid quantity (GPA) can be determined
by dividing the pounds of chemical needed per tankful
by the number of pounds in one gallon (acid
equivalent) .
2 . Band Spraying
Calibration of a band sprayer, where only a part of the
total area is sprayed, can be determined by the following
steps :
Step 1. Measure and mark 300 feet and calculate the amount
of liquid used to spray this measured course.
Step 2. Determine the sprayer rate (GPA) by this formula:
2
Gal. /Acre = 43,560 ft /acre x Gallons used
300 ft. X Band width (ft.) x No. bands sprayed
Example: One half gallon of spray material was
used to spray 300 feet using 2 nozzles
spraying 12 inch bands.
43,56 X 0.50 gal. = 36.3 gal. /acre
300 ft. X 1 ft. X 2 bands
Step 3. Determine the number of acres that can be sprayed
with one tank and the amount of pesticide that should be
added to the tank. This can be done in the same manner as
in the nozzle volume method.
NOTE: Acres sprayed include only that covered by
the spray pattern and not the area between.
3 . Granular Application
Granular application equipment may be calibrated by
collecting granules from one or all delivery tubes. Measure
the amount collected in pounds. Use the same procedure as
for the nozzle volume method. If granules are applied in
bands, use the same procedure as for band spraying.
4 . Hand Held Sprayer
Use the following procedure to calibrate and fill a hand
sprayer :
Step 1. Fill sprayer with carrier, select pressure and
spray pattern, and measure a 20 x 20 foot test area.
Step 2. Determine time in seconds needed to spray the test
area .
32
step 3. Refill the sprayer and run it for the amount of
time determined in Step 2. Catch and measure the spray
released .
Step 4. Determine the total area that can be sprayed with
one tankful by this formula:
2
Total Area = Tank size x Test area (ft. )
Gallons to spray test area
Step 5. Determine the amount of pesticide to add to the
sprayer :
Pesticide _ Total area (Step 4) x Label Rate (Gal, /Acre)
in Tank 43,560
Step 6. Spray using same pressure and spray pattern as
during test.
5 . Air Blast Sprayers (Orchards)
Using air blast sprayers, speed of travel is the most
important factor that ensures good coverage by the
pesticide. Equipment speed must be slow enough to allow the
air blast to penetrate the surrounding air and carry the
spray to the trees. Sprayer speed should be about 2 mph and
never slower than 1/2 mph or greater than 3 mph.
Air should be directed toward the top 1/3 of the trees.
Edges of the air blast should just clear the tree top and
bottom. Vanes or movable air outlets on the sprayer can be
adjusted to direct the air. Consult the manufacturer's
manual for more precise adjustment of the air stream.
The following procedure is suggested for calibration using
two-side delivery:
Step 1. Test run the sprayer using water to determine the
best pressure and ground speed. Watch the trees to
determine at what speed the air penetrates the trees and
turns the leaves.
Step 2. Fill the tank with water and, at the speed and
pressure determined from Step 1, spray a measured course
(300 ft.). Measure the amount of water needed to refill the
tank and calculate sprayer output using this formula:
Output (GPA) = Row space (ft.) x 300 ft. x Water used (gal.)
43,560 sq.ft, per acre
Step 3. Determine the number of acres that can be sprayed
with one tank:
33
Total acres/tank = Tank size (gal.)
Sprayer output (GPA)
Step 4. Consult the label application rate if appropriate
and determine the amount of pesticide that should be added
to the tank:
Pesticide = Total acre/tank x Label Application Rate (GPA)
NOTE: This method is correct only if all rows in
the orchard are to be sprayed. If spraying is planned
for alternate rows, then an adjustment must be made to
the formula in Step 2 .
If the row space changes among orchards, then the figures in
Steps 2 through 4 must be recalculated (it is not necessary
to repeat the measured course) .
Rates for various chemicals, such as Diazinon in cherries,
state "spray to cover". This essentially means spray until
all leaves are wet or when pesticide begins to drip. Any
unnecessary pesticide drip should be avoided. Where labels
state "spray to cover", it is essential that Step 1 be done
carefully. Mix the pesticide and carrier according to the
label dilution rate. Steps 2 through 4 are supplemental in
these instances only if you wish to know the spray rate per
acre .
6 . Ornamental Sprayers
Most label rates for ornamental trees and shrubs state
"spray to cover" or "drench". For this reason, it is not
necessary to know sprayer output unless the operator wishes
to know the volume of pesticide applied to a tree. It is
essential, however, to determine the correct pressure that
penetrates the foliage and to apply pesticide only to the
point of runoff. Pesticide that drips to the ground is
wasted and may be environmentally harmful.
It is recommended that applicators and their operators
experiment with their equipment filled with plain water
utilizing various pressures and disc sizes (4,6,8,10, etc.).
By working against a wall or large tree, the proper
pressures, discs and spray patterns can be determined.
7 . Sample Calculations
The following formulas and examples may be useful study aids
or may be helpful when you calibrate your sprayer:
34
To determine acres sprayed
a .
Acres sprayed = Swath width x distance travelled
43,560 ft. per acre
For example, what acreage was sprayed by a boom sprayer
with a spray swath of 25 ft. that made 10 passes (no
swath overlap) in a field 500 ft. long?
25 ft. X (500 ft. X 10)
43,560 FtT/acre
2.9 acres
b. To determine rate (GPA) when acreage sprayed and
spray volume is known:
Rate = spray volume (gal.)
acres sprayed
For example, if 2.9 acres were sprayed and 36 gallons
of tank mixture was used, what was the rate per acre?
36 gal.
2.9 ac .
12.4 gal. /acre
c . To determine the amount of pesticide applied per
acre when tank mixing rate is known:
Pesticide/ac . = Spray rate (GPA) x label mixing rate,
for example, spray rate was 12.4 gal. /acre and the
pesticide was tank mixed 1 quart per 100 gallons
carrier. How much pesticide was applied per acre?
12.4 gal/acre x 1 qt .
100 gal.
.124 qts. or 1/2 cup
d. To determine how much pesticide should be added to
your tank when the sprayer rate is known.
Pesticide = Tank size (gal.) x label rate (GPA)
sprayer rate
For example, you have test calibrated your sprayer and
it applies 12 gallons of water per acre. The tank
holds 200 gallons and the pesticide label rate suggests
1 qt./acre. How many qts. of pesticide should you add
to your tank to achieve this rate?
200 gal, x 0.25 gal./ac.
12 gal./ac.
4.17 gal .
16.7 qts .
e. You have test calibrated your sprayer and found it
to apply 7 gallons water per acre. You plan to apply
Benlate to beans, and the label rate is 10-20 gal.
carrier per acre. What is your next step?
35
Recalibrate your sprayer to increase the rate (increase
pressure, check nozzles for improper size, decrease
tractor speed, etc.)
f. To determine correct speed if your test run speed
results in sprayer rate that is too low.
New speed = Present speed (mph) x sprayer rate (GPA)
desired rate (GPA)
Using example, you decide to apply 15 gal. carrier per
acre. At 7 mph the sprayer rate was 7 GPA. What is
the correct speed?
7 mph X 7 GPA
15 GPA
3 . 3 mph
36
CHAPTER V
AERIAL EQUIPMENT AND CALIBRATION
The subject of aerial spray equipment and accessories is a
complex subject suitable for engineers and experienced pilots;
however, many aspects of aerial application are similar to ground
application. For example, sprayers are basically constructed of
the same components. Calibration is accomplished in much the
same way except that speeds are much greater and rates much
lower. The following chapter contains a general discussion of
aerial equipment and accessories and calibration of aerial
sprayers. For a more comprehensive discussion of aerial spraying
applicators read "The Use of Aircraft in Agriculture" by Akesson
and Yates.
A . Types of Aircraft
There are several classes of aircraft that may be utilized for
the application of pesticides. These classes include:
1. High wing monoplanes are not primarily designed for
applying pesticides, but do provide good visibility,
handling, and low maintenance cost.
2. Low wing monoplanes are steadily increasing in use
today. Generally, these planes provide increased safety by
providing better visibility, stability, and protection to
the pilot.
3. Biplanes are the predominant single engine aircraft
used for aerial application in some sections of the country.
4. Multi-engine aircraft are utilized extensively in
forest and rangeland application.
5. Helicopters have some advantages over fixed wing
aircraft, i.e. operate at slower speed; increased safety;
improved accuracy of swath, coverage, and placement of the
chemical; and they may be operated without airport
facilities .
B. Drift
Perhaps the most serious problem associated with aerial
application of pesticides is drift of pesticides to non-target
areas. Several features of aerial application accentuate this
problem:
1. The requirement of low application rates means that
spray droplets must be small so that coverage (droplets per
acre) will be adequate. Smaller droplets have a greater
tendency to drift; droplets 30 microns and smaller remain
suspended in air. Spray droplets should be about 100
37
microns to minimize drift. Table 3 gives an indication of
the effect of droplet size on drift.
Table 3.
SPRAY DROPLET SIZE AND ITS
EFFECT ON SPRAY
DRIFT
Drop Diameter
Particle Type
Weather
Distance Moved by 3
Microns
1/
Elements
MPH wind in 10' Fall
400
Coarse aircraft spray
Light rain
8.5'
150
Medium aircraft spray
Mist
22'
100
Fine aircraft spray
48'
50
Air carrier spray
178'
20
Fine sprays & dusts
Fog
1,109'
10
Usual dusts & aerosols
4,435'
2
Aerosols
21 miles
1/ A micron is about 1/25,000 inch
— From Akesson & Yates,
Ann. Rev. Entom. Vol. 9, 1964
2. Pesticides are generally released at greater heights
than from conventional sprayers. This is done to achieve
good coverage but also results in pesticide drift caused by
wind, convection currents, and aircraft turbulence.
Aerial applications should be conducted when the air is
still or nearly so. By spraying early in the morning,
convection currents which form at temperatures 85_F. and
above can be avoided.
The flight path directly affects the amount of drift. If
the aircraft is climbing, there will be more down push and
less spray pulled into vortices. If the aircraft is
descending, the wing or rotor tip vortices will pull more
spray aloft; various portions of the spray pattern will be
disturbed as well. Level or slightly ascending flight is
usually best to alleviate both effects.
Tests show that there is an increase in drift with more
swaths. Barriers near the target area (trees) may help
reduce drift and confine it to the target area. For a look
at how different factors affect drift, see Table 4.
The following factors can help to reduce pesticide drift:
a. Increase droplet size by the use of invert
emulsions (water in oil mixtures), viscosity additives,
or foam producing additives.
b. Increase droplet size by using nozzles with larger
orifices or by using a jet nozzle.
38
Table 4 .
The Effect of Various Factors on Pesticide Drift
Less
Drift
More
Lower
A.
Aircraft altitude
Higher
Lower
B.
V^Jind speed
Higher
Larger
C.
Droplet size
Smaller
Lower
1. Pressure
Higher
Jet
Greater
2. Nozzle type
3. Nozzle capacity
Smaller
Larger
4. Orifice size
Smaller
Round
5. Orifice shape
Sharp Angles
Lower
6. Air shear on spray
Higher
Higher
7. Surface tension
Lower
Higher
8. Spray density
Lower
Higher
9. Viscosity
Lower
Down
D.
Vertical air motion
Up
Reduced
E.
Air stability
Greater
Slower
F.
Aircraft turbulence
1 . Speed
Faster
Climbing
2. Flight direction
Falling
Narrower
G. Swath width
Wider
Less
H. Number of contiguous swaths
More
L.E. Warren,
From
: Weed Control, Training Session
c. Limit boom length to no more than 3/4 of the wing
span .
d. Control droplet size by using the correct
pressure .
e. Use atomizers (spinners) at the proper rpm.
f. Fly at the proper altitude.
g. Apply pesticides early in the day before
convection currents form.
h. Spray only during calm weather.
i. Choose pesticide formulations that are not vola-
tile .
39
c.
Viscosity Modifiers
Viscosity modifiers are agents which simply increase the
viscosity of water or oil carrier. They will create a particulate
foam, thixotropic nature (gel to liquid upon shaking) , or produce
a two-phase mix of oil and water called invert emulsion. These
additives increase droplet size and hence, decrease drift.
A particulating agent is a water swellable polymer that absorbs
water but does not dissolve. Particulating agents are probably
the most effective drift control agents for water soluble
herbicides .
Thixotropic wax products act differently than plain thickening
agents. When they are added to water, thickening occurs, but
when dispersed under pressure or shear, the material thins and
thickens again as the spray leaves the nozzles.
An invert emulsion is formed when an oil phase in the water-oil
mixture becomes continuous and the water is dispersed in cells.
Invert emulsions reduce evaporation because the oil film
surrounds the water. Various inverts can reduce drift by as much
as GO-99 percent in comparison with normal water sprays.
Invert emulsions can be mixed in the tank before spraying or in
the line or pump as they are being sprayed (bi-fluid system) .
The viscosity of invert emulsions is increased by using more
inverting agent, decreasing the oil, and increasing agitation.
Oil to water phase ratios may range from 1 part oil to 2 parts
water to as high as 1:15.
Individuals interested in viscosity modifers should consult with
technical representatives of chemical companies. Extension
Service Personnel, or the Montana Department of Agriculture.
D . Equipment for Dispersing Pesticides
Application equipment can be constructed for dispersing dry or
liquid pesticides. Since applicators can be asked to apply
either type, equipment such as hoppers are often constructed so
that liquid or dust formulations can be applied. Following is a
discussion of equipment for aerial application of liquid and/or
dry pesticides in fixed wing or rotary wing aircraft.
1 . Dry Material Application Systems
In a fixed wing aircraft, chemicals are dispensed primarily
by ram-air spreaders and spinners . In a ram-air spreader,
dry materials are metered from the hopper into the propeller
slip stream. Ram-air systems do not have the capacity to
spread materials in a wide swath. This led to the
development of spinners . These devices consist of spinning
vanes mounted under the hopper that throw material outward
in a uniform pattern. Some equipment, to further increase
40
spreading power, utilizes a blower to force material into
the spreader. The use of spreaders and blowers can nearly
double the swath width.
In helicopters , two types of dispensers are used.
1) A blower driven by the engine forces material from
two side tanks and out short booms. The material may
be spread using spinners instead of the boom.
2) A single hopper can be suspended on a cable and
material dispensed using spinners. This method
eliminates the problem of aircraft trim caused by
uneven emptying of side tanks.
Agitators, to insure even dissemination of material from the
tanks, may or may not be present. They are essential for
materials smaller than 60 mesh. Their use will help insure
even application by providing an even flow of material.
The hopper or tank for dry materials should have many of the
characteristics of a tank for holding liquids. Corners
should be rounded and the sides should be steep to insure
unloading of the chemical. Usually a slope of 50_ to 55_ is
adequate. Tanks can often be used for dry or liquid
materials by replacing a bolt-on plate on the tank bottom
with a hopper.
2 . Liquid Material Application Systems
There are two types of spray systems for fixed and rotary
wing aircraft:
1) pressure type - the spray is applied under
specific pressures.
2) gravity feed - the flow of spray solution from the
tank to dispersing unit relies upon gravity.
Aircraft spray dispersal equipment consists of a tank(s),
pump(s), pressure regulater, line filter, flow control
valve, boom and nozzles. Swath widths of 40 to 60 feet, in
the application range of 1 to 10 gallons per acre are normal
when material is released 5 to 8 feet above the ground.
a. Tanks for fixed wing aircraft are usually mounted
internally, often ahead of the pilot and aft of the
engine, however, quick release belly tanks can be
mounted to the aircraft bottom. This permits rapid
jettison of the tank should the need arise. Also,
aircraft not primarily used for spraying can be
modified to do so.
41
In rotary wing aircraft, tanks are mounted externally
on the side or underneath.
All tanks should have emergency dump valves located on
the tank bottom. Internal baffles are required to
prevent rapid shifts in fluid.
b. Two types of agitation systems are utilized to
maintain suspensions and mixtures of chemical.
Mechanical systems rely on paddles to maintain
agitation. Hydraulic systems utilize a return flow
from a large capacity pump. A rule of thumb is that
the flow rate should be 10 GPM for every 100 gallons of
tank capacity.
c. The most common pump is that driven by a small
propeller in the slip stream of the aircraft engine
propeller. The efficiency of this type of pump is low
and many newer aircraft are equipped with hydraulic
piston pumps or electric pumps.
Helicopter pumps are usually driven by a PTO.
Centrifugal pumps are the most common type where
application rates are 1-10 gal. /acre. Where higher
pressures are needed, as for aerosols, or where pump
discharge is greatly reduced, other pump types such as
gear or roller are used.
d. Pressure regulators or by-pass relief valves are
utilized to maintain a constant spray pressure.
Pressure regulators are located between the pump and
boom and include a quick closing shut-off valve. These
valves allow the spray system to be opened and closed
instantly .
e. The main control valve is usually 3-way. In the
"spray off" position, the valve directs flow from the
pump back into the tank through a venturi section.
This action maintains a slight vacuum in the boom to
prevent pesticide dribble, and provides recirculation
agitation in the tank. A third valve position allows
the tank to be filled or emptied through the boom.
f. Screens or filters are generally located in three
places in liquid systems. A coarse screen at the tank
bottom keeps debris from entering the pump. The most
important screen is one located between the pump and
the booms. It is usually 25 to 100 mesh (10-40
openings per centimeter) and can be removed easily for
cleaning. Mesh size depends upon nozzle orifice size
so that particles that might plug the nozzles can be
removed. A third screen is usually placed just before
each nozzle orifice.
42
g. Pipes and fittings usually have the following
characteristics that help prevent pressure losses;
1) For application rates over 2 gallons per
acre, all main piping and fittings are 1-1/2
inches inside diameter.
2) For application rates of 1/2 to 2 gallons per
acre, all main piping and fittings are at least 1
inch inside diameter.
3) For ULV applications, hoses to individual
nozzles should be 1/8 inch inside diameter. Main
line hoses and fittings should be at least 3/8
inch inside diameter.
The number of bends and joints should be minimized.
All hose connections should be double clamped and lines
under pressure should not run through the cockpit.
h. Booms for fixed and rotary wing aircraft, although
mounted differently, are basically the same in
construction. Boom pipes are round or aerodynamic in
cross section. In fixed wing aircraft, they are
mounted on the trailing edge of the wing and usually
are 3/4 the wing span length.
i. Nozzles used in aerial spraying are basically of 4
types ;
1) The jet or solid stream nozzle produces a jet
of coarse droplets useful for coarse sprays such
as 2,4-D.
2) Hollow cone nozzles, identified because of
their spray pattern, produce small droplets.
3) The flat fan nozzle produces a fan shaped
pattern and is useful in reduced volume
applications .
4) An atomization nozzle produces a true aerosol
spray in a cone shaped pattern.
j. Atomizers, in addition to the atomizing nozzle,
include a variety of spinning screen cages, discs, and
wire brushes. They are usually driven by fans or
electric motors. Atomizers produce droplets of more
uniform size and are useful in low volume spraying such
as grasshopper or mosquito control.
Droplet size is influenced by a complex interaction
among pressure, spinner speed, air shear, and
discharge angle. For example, as pressure (flow rate)
43
increases, droplet size increases. As spinner velocity
increases, droplet size decreases. The angle of
discharge from the nozzle in relation to the airstream
influenced droplet size. Smaller sized droplets will
be produced if nozzle discharge is directed at 90_
relative to the slip stream.
E . Safety and Maintenance
The safety section in the General Pesticide Training Manual also
applies to aerial applicators. The following additional rules
also apply:
1. Because pilots must fly through previous swaths, a
clean air supply is necessary. If a filtered air helmet is
not available, use an approved respirator.
2. No hoses, valves, or any portion of the system carrying
pesticides should pass through the cockpit.
3. Components of the spray system inside the fuselage
should be accessible for cleaning, maintenance, and repairs.
4. The critical demands of aerial pesticide application
require regular maintenance. The seasonal nature of
pesticide application lends itself to inspections and
repairs during idle periods.
F . ULV Application
The present trend in pesticide application is to apply highly
concentrated material at low rates. Ultra low volume (ULV) rates
for mosquito control are as low as 0.1 gallon per acre.
The application of ULV formulations requires the use of special
equipment and application procedures. Conventional aircraft
spray systems can be modified to accomodate ULV formulations. A
small ULV system can be installed separate from the dilute system
and can be removed upon completion of ULV operations.
The following points should be observed when applying ULV
applications; ULV systems must deliver fine droplets to be
effective. This can be accomplished by utilizing spinning or
flat fan nozzles discharging 0.1 GPM or less at 40 to 55 psi.
Gaps in the distribution pattern can be avoided by using not less
than four flat fan nozzles. For helicopter operations, a single
spinning nozzle may provide adequate output at very low rates
such as required for mosquito control.
Because of the fine droplets produced by ULV systems, the
location of the nozzles is important. Extreme outboard nozzles
must be located away from the wing tips on fixed wing aircraft to
avoid spray entrapment in the wing tip vortices. Central nozzles
can be shifted to the right to compensate for propeller wash.
44
ULV application should be made at the altitude that will achieve
the optimum spray width strip. As wind velocity increases, the
aircraft altitude should decrease.
Carriers used in ULV formulations may cause premature wearing of
certain equipment parts. For instance, the carrier for Malathion
will corrode rubber and neoprene. To minimize chemical damage to
spray equipment; seals, hoses, and nozzle diaphragms should be
checked regularly and replaced if corrosion has begun. Nozzle
screens should also be checked regularly since the smaller tips
become clogged more easily.
G . Calibration
The same variables that apply to ground equipment also apply to
aerial calibration, i.e. speed, pressure, nozzle spacing, and
swath width. Aerial applicators should be familiar with the
sections in this manual dealing with ground equipment and
accessories, ground equipment calibration and maintenance.
Precise calibration is essential in order to apply the correct
rates and to guard against crop injury caused by overdoses of
pesticide .
1. Swath width must be known before calibration can
proceed. Because aircraft wheels nearly touch the crop
during application, swath width is about the same as boom
width or is related to the ram-air or spinner type spreader.
To make a precise measure of swath width, flights can be
made over collecting surfaces arranged in a line
perpendicular to the line of flight. Dyed sprays can be
deposited on cards or plastic plates and the amount of
pesticide or liquid deposited can be measured. Deep baskets
or buckets or oiled surfaces can be used to collect
granules. From the information gathered, swath width and
deposit pattern can be determined. Be sure to determine
effective swath width, or that swath width in which
pesticide was deposited in sufficient quantity to give
control .
2. VJhen air speed and swath width are known, the rate at
which pesticides should be dispensed can be found using this
formula:
Rate (GPM) = Label rate (GPA) x Swath width x Air speed
495
For example, the 100 mph aircraft has a 40 foot effective
swath width. Label rate instructions call for 10 GPA. At
what rate should the aircraft be calibrated?
10 gal./acre X 40 ft. x 100 mph ^ gal. /min
49b
45
For dry materials, the discharge rate thus obtained can be
established by actual flight tests for ram-air spreaders.
Spinners can be calibrated by operating the equipment on the
ground .
For liquid pesticides, the discharge rate can be obtained by
selecting nozzle type and size. The number of nozzles on
the boom can be adjusted to give the proper discharge rate
to determine the correct number of nozzles, use the
following formula:
No. Nozzles = Discharge rate (GPM)
Flow rate per nozzle (GPM)
For example, flow rate should be 80.8 GPM and the flow rate
for the nozzles selected is 6.7 GPM. How many nozzles will
give the proper flow rate?
80.8 GPM
6.7 GPM
12 nozzles
Small alterations in discharge rate can be made by adjusting
pressure .
3. To determine the number of acres that can be treated
with one tank or hopper, use this formula:
Total acres = Tank size (gal.)
Rate per acre (GPA)
4. As a final check on calibration, it is desirable to
make an actual flight check. After the tank is filled with
a known quantity or to a marked level, a flight is given
time or distance is made. The amount of material applied
can then be determined by filling the tank to its original
level. The quantity applied per acre can be determined and
will indicate the accuracy of calibration. Table 5 provides
a quick reference for determining acreage sprayed for a
given swath width and field length.
46
Table 5
Acres covered for given field lengths and swath widths
Swath Width (ft)
Field Length 20 25 30 35 40 45 50
65 75
85 95 100
ft. (mi)
1
320
(1/4)
0.6
0.75
0.9
2
640
(1/2)
1.2
1.5
1.8
3
960
(3/4)
1.8
2.3
2.7
4
280
0)
2.4
3.05
3.6
2
4.9
6.05
7.2
3
7.25
9.1
10.8
4
9.7
12.1
14.4
5
12.1
15.15
18.0
*Acres = (Length in ft. x width
acres*
1.1
1.2
1.4
1.5
1.7
2.1
2.4
2.7
3.0
3.3
3.2
3.6
4.1
4.6
5.1
4.2
4.8
5.5
6.1
6.7
8.4
9.8
10.9
12.1
13.3
12.6
14.5
16.4
18.2
20.0
16.8
19.4
21.8
24.2
26.6
21.0
24.2
27.3
30.3
33.3
in ft./43,560)
2.0
2.3
2.5
2.9
3.0
3.9
4.5
5.1
5.7
6.1
5.9
6.8
7.7
8.7
9.1
7.8
9.1
10.2
11.6
12.1
15.6
18.2
20.8
23.0
24.2
23.4
27.3
30.8
34.6
36.4
31.2
36.4
41.2
46.0
48.5
39.3
45.5
51.4
57.6
60.6
47
1*1
r , 1
t 't
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A . A :
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Appendix
CONVERSION FACTORS FOR UNITS OF MEASUREMENT
Units of Volume - Liquid Measure
3/4 fl. dram
3 teaspoons =
2 tablespoons
8 fl. ounces
2 cups =
2 pints
4 quarts
1 kilollter
1 liter
1 milliliter
12 Inches
3 feet
10.5 feet
1760 yards
1 kilometer
1 meter
1 decimeter
1 centimeter
144 sq. inches =
9 sq. feet
30.25 sq. yards
160 sq. rods =
43560 sq. feet
] hectare
1 sq. meter =
1 sq. decimeter =
1 sq. centimeter =
1 teaspoon =
1 tablespoon
1 fl. ounce
1 cup
1 pint
1 quart
1 gallon
1000 liters
1000 milliliters =
1000 microliters =
Units of Length
1 inch
1 foot
1 yard =
1 rod
1 mile =
1000 meters
10 decimeters =
10 centimeters =
10 millimeters =
Units of Area
1 square inch =
1 square foot =
1 square yard
1 square rod =
1 acre
1 acre
10,000 sq. meters
100 sq. decimeters =
100 sq. centimeters =
100 sq. millimeters =
4.9 milliliters (ml.)
14.7 ml.
29.57 ml.
236.58 ml.
473.17 ml.
946.33 ml.
3.79 liters
264.2 gallons
1.06 quarts
0.03 fl. ounces
2.54 centimeters
3.05 decimeters
0.91 meter
5.03 meters
1.61 kilometers
0.62 miles
39.37 inches
0.33 inches
0.39 Inches
6.45 sq. centimeters
929.03 sq. centimeters
0.84 sq. meters
25.29 sq. meters
4046.4 sq. meters
0.40 hectare
2.47 acres
1.20 sq. yards
0.11 sq. feet
0.15 sq. inches
437.5 grains
16 ounces
2000 pounds
1.12 short tons
1 kilogram
1 gram
Units of Mass (metric and
1 grain
1 ounce
1 pound
1 short ton
1 long ton
1000 grams
1000 milligrams
Avoirdupois)
1000 milligrams
28.35 grams
0.45 kilograms (kg).
907.2 kg
1016.0 kg
2.2 pounds
0.35 ounces
48
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