Application of concentrated spray with hand equipment

MISSING IMAGE

Material Information

Title:
Application of concentrated spray with hand equipment
Physical Description:
6 p. : ill. ; 27 cm.
Language:
English
Creator:
Potts, S. F ( Samuel Frederick ), b. 1900
United States -- Bureau of Entomology and Plant Quarantine
Publisher:
U.S. Dept. of Agriculture, Agricultural Research Administration, Bureau of Entomology and Plant Quarantine
Place of Publication:
Washington, D.C
Publication Date:

Subjects

Subjects / Keywords:
Spraying equipment   ( lcsh )
Spraying and dusting in agriculture   ( lcsh )
Genre:
federal government publication   ( marcgt )
non-fiction   ( marcgt )

Notes

General Note:
Caption title.
General Note:
"E-824."
General Note:
"October 1951."
Statement of Responsibility:
by S.F. Potts.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030337810
oclc - 780443813
System ID:
AA00025224:00001

Full Text
L ..
' .'i October 1951 E-824



United States Department of Agriculture
Agricultural Research Administration
Bureau of Entomology and Plant Quarantine



APPLICATION OF CONCENTRATED SPRAY
WITH HAND EQUIPMENT

By S. F. Potts, Division of Forest Insect Investigations



The development of concentrated sprays for insect control has so
increased the speed and ease of application of insecticides that hand
apparatus can be used to treat much larger areas than has been possible
with dilute sprays. With this development have come improvements in
such equipment. The equipment available in 1942 was described by the
author in E-574, entitled "Equipment Available for Applying Concentrated
Sprays." The purpose of this publication is to bring up to date the informa-
tion on hand equipment for the application of concentrated sprays. In this
paper a concentrated spray is considered to be one in which the concen-
tration of the toxicant is more than seven times the concentration in an
ordinary dilute spray.
Hand Atomizers


Most hand atomizers
utilize a plunger-type air
pump to develop a continu-
ous air pressure of 2 to 5
pounds per square inch.
In one type the air pressure
is applied to the surface of
the liquid in the container
to force it through nozzles
with orifices 1/32 to 1/16
inch in diameter. In another
the liquid is drawn from the
spray tank through a tube by
.. ". """_ means of suction caused by
Sair from the pump rushing
across the open end of the
tube (fig. 1).


Figure 1. --Hand atomizer.




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Tihe second type of atomizer produces drops averaging 20 to 50
microns in diameter and can spray suspensions as well as solutions and
emulsions. It is usually preferred to the first type, which is more
expensive and has a tendency to clog when suspensions are used. This
atomizer has a liquid orifice 1/12 to 1/8 inch in diameter, large enough to
prevent frequent clogging. It discharges liquid at a slow rate, permitting
fine atomization and thus lessening the tendency to overspray. The air
orifice is 3/32 to 1/8 inch in diameter. For any given air pressure, drop
diameter and volume decrease with increase in size of the air orifice and
with decrease in size of the liquid orifice. The size and position of the
liquid tube in relation to those of the air orifice of the air pump are very
important. The liquid orifice should be 1/32 to 1/16 inch forward of the
air orifice and 1/64 inch below its center.
There is still room for improvement in hand atomizers. Among the
weaknesses of those on the market today are (1) corroding of the tank and
liquid tubes, (2) short life of the air-pump plunger, (3) tendency for the
spray to drip onto floors or furniture, (4) inability of the operator to see
the liquid in the spray tank or to measure precisely the quantity of liquid
that is being applied, (5) difficulty of stirring the spray mixture in the
tank, and (6) difficulty of cleaning and rinsing the sprayer.
Some of these weaknesses can be eliminated by using a sprayer tank
of glass or plastic instead of metal. However, if a tank is constructed
of metal, copper or prime galvanized metal should be used. Some
practical way of installing a feed tube that can be readily removed and
cleaned with a wire or pipe cleaner would be advantageous.
Extension rods or nozzles that permit directing the spray at any
desired angle are useful for spraying plants that are less than 2 feet
high.

Electric Atomizers

There are two types of hand atomizers that are operated by electricity.
In one a 1/10- to 1/3-hp. electric motor is used to drive a small compressor
which delivers compressed air through an orifice in the nozzle. By this
method the spray can be atomized as finely as by an aerosol bomb. The
second type employs a fan or blower to atomize and propel the spray mist.
It has much greater drive, air volume, and spread of air stream than the
first type.

Knapsack Sprayers

The usefulness of knapsack sprayers for applying concentrated sprays
depends on the rate of delivery and efficiency of the nozzles. Most noz-
zles deliver too much spray and do not atomize it sufficiently. Knapsack
sprayers are normally operated with a direct pressure on the liquid of





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-^ ^30 to 75 pounds per square inch, and atom-
Sization is effected by conventional nozzles.
Pressure may be developed by compressed
air, as from an air-plunger pump in round
tanks (fig. 2), or by hydrualic pressure
developed by a hand-operated plunger (fig. 4)
or by a diaphragm or plunger pump.
The knapsack sprayers now available are
not very satisfactory for applying highly con-
centrated suspensions. The larger orifice
Needed to disperse the wettable powder delivers
too much liquid, and the drops are too coarse.
For dispersing solutions and emulsions oil-
burner type nozzles that deliver 2.5 to 6 gal-
lons per hour are satisfactory unless it is
necessary to drive the mist to the underside
of dense foliage. To avoid clogging it is
important to start with a clean tank equipped
Figure 2.--Compressed- with a 14- to 20-mesh strainer on the intake
air knapsack sprayer pipe at the bottom. The mixture should be
with hand-operated air well shaken and then poured into the tank
plunger pump. through a funnel containing a 30- to 40-mesh
strainer. It should also be shaken during
the spraying operation. The application should be made with a pressure
of at least 35 pounds per square inch. When a -
spray job is completed, the sprayer should be
thoroughly rinsed and dried to prevent rusting.
With some types of knapsack sprayers carbon '
dioxide can be used to provide pressure for
applying the liquid (fig. 3). & "
The common faults of present-day knapsack --
sprayers are listed below with seme suggested
remedies, for the information of manufacturers |
and users of such equipment. '\
(1) The hose is too short. A length of 4 to 5 .
feet is needed to provide sufficient reach and
leverage. i
(2) Gaskets, plunger rubbers, and packing
are easily decomposed by oil solvents, oils, and .,i
various other chemicals. "
(3) The mixture in the tank is not completely'" ... -
discharged. This fault can be remedied by
having the intake pipe extended to the tank's
bottom. FieLure 3.--Knapsacki
(4) They do not have durable, dependable sprayer using carbon
shut-off valves that do not leak. dioxide for procl u cing
prosS Ure.




-4-


Figure 4. --Knapsack sprayer
with hand-operated hydraulic
plunger pump.


rates per acre are given in table 1.
For treating barns, poultry houses, and other buildings with residual
sprays, the quantity to apply per unit area of floor, ceiling, and wall
varies with the insect, the insecticide, the toxicant concentration, and
the deposit desired. Table 2 lists some quantities of sprays at different
concentrations equivalent to given dosages of toxicant per 1,000 square
feet (0.023 icre) of surface.


(5) The sprayers, particularly those
of the hand-operated hydraulic types,
tend to leak onto the back of the operator.
This is a serious fault when certain
solvents and poisons are used. Air-
tight gaskets and covers help remedy
this condition.
(6) The tanks tend to corrode and
rust.
(7) Extention rods longer than 3 feet
are too heavy. A light-weight metal,
such as magnesium, should be used. If
it is still too heavy, the extension rod
should be strapped on a bamboo pole or
placed inside of it by running the rod
through a hole drilled the length of the
pole.

How to Determine
Amount of Spray to Use

For treating shrubs or areas of low
growth it is necessary to know the size
of the area to be covered in order to
determine the quantity of insecticide to
apply. The quantities of spray required
for small areas equivalent to various






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