Insecticide duster


Material Information

Insecticide duster
Physical Description:
5 p. : ill. ; 27 cm.
Chisholm, R. D
United States -- Bureau of Entomology and Plant Quarantine
U.S. Dept. of Agriculture, Agricultural Research Administration, Bureau of Entomology and Plant Quarantine
Place of Publication:
Washington, D.C
Publication Date:


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


General Note:
Caption title.
General Note:
General Note:
"April 1947."
Statement of Responsibility:
by R.D. Chisholm ... et al..

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030364017
oclc - 783775048
System ID:

Full Text

April 1947 ET_ 237

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


By R. D. Chisholm and L. Koblitsky, Division of Insecticide
Investigations, and W. C. Fest and iE. D. Burgess,
Division of Fruit Insect Investigations!17

The operation of dusters to distribute insecticides often
depends on compression of air by means of a plunger. In such
dusters all the compressed air is conducted into an insecticide
container, thereby causing the insecticide to become entrained in
the air stream and to be discharged through a vent. Because of
the small volume of air compressed during each stroke of the
plunger and the low velocity of the entrained insecticide, only a
small area can be treated with a single stroke. Therefore, the
treatment of a large arec is laborious and time-consuming, and ag-
glomerates of partially dispersed insecticide may be deposited.
The area of effectiveness may be increased by operating the plunger
morn rapidly, but this may result in increased deposition of ag-
glomerates. These difficulties were encountered during a study of
methods for the distribution of DDT in refrigerator cars as a
TJapanese beetle quarantine treatment.

The deficiencies of conventional dusters have been substan-
tially eliminated in experimental dusters that have been constructed
and used in large-scale tests. In one of the dusters air compressed
by means of a plunger is forced into a delivery pipe attached hori-
zontally to the top of an insecticide container. About one-half of
the compressed air is diverted from the pipe by means of a scoop
and is conducted into the container. The insecticide is entrained
in this diverted air stream and then conducted through a connected
outlet into the pipe, where it is further dispersed and discharged
by the remainder of the air, which has passed by the scoop.

The duster here described is adaptable to specific require-
ments by establishing the proper relation of the rate of intro-
duction of the air to the diameter of the pipe and to the propor-
tion of the air that is diverted to cause the insecticide to enter
the pipe. With experimental models it was possible to increase
the area treated with a single stroke of the plunger, to improve

i/The authors are indebted to L. B. Parker, of the Division of
Fruit Insect Investigations, for the photographs presented in this

the uniformity of distribution, and to reduce the proportion of
agglomerates deposited, as compared with those deposited by a con-
ventional hand duster. pest results were obtained when a cylinder
of liquefied gas, such as carbon dioxide or Freon-12 (dichloro-
difluoromethane), was substituted for the plunger and the pipe was
attached to the bottom of the insecticide container to facilitate
its charging. Carbon dioxide was found to be well adapted, since
it is cheap, readily available, and causes delivery in a matter of
seconds of a thoroughly disintegrated insecticide mixture at high
velocity throughout a refrigerator car. This duster includes two
insecticide containers to provide for delivery into both halves of
the car simultaneously.

Description of Duster

The duster adopted for the treatment of refrigerator cars
(fig. 1) consists of a trigger-controlled carbon dioxide cylinder
(fire extinguisher) (A) with the distributor screwed onto its out-
let pipe. The distributor consists of a 1/8-inch (pipe-size) tee
(B), into which are screwed two 1/8-inch by 5-inch delivery pipes
(C and D) to which 45-degree elbows (P, and F) are attached. In-
secticide contfiuers (G and H) are soldered onto the tops of C and
D, respectively.

The construction of insecticide container H is shown diagram-
matically in figure 2. It is assembled by soldering a 1-inch pipe
cap (I) onto delivery pipe D and drilling a 3/16-inch and a 1/4-inch
outlet hole (J) trzu:h both. A gas-inlet tube (K), made from. a
piece of 3/16--inch (o.d.) by 3 1/2-inch tubing, is soldered into
the 3/16-inch hole. A lo:&-itudinal section 7/16 inch long is re-
moved from the lo',er end of the tube and the remaining section is
shaped to form the scoop, which is placed so that its concave sur-
face feces into the stream of :-as and occupies about half of the
cross-section area of the pipe. A 1-inch by 3-inch nipple (L) is
screwed into pipe can I and closed by a 1-inch pipe cap (!). The
insecticide container is charged with cap 11 removed and is ready
for use when the cap has been screwed firmly in place. Container
G is a mirror iL. e of H.

Operation of the Duster

For the treatment of refrigerator cars, the duster is placed
either near the door on the floor or on top of the load, with pipes
C and D parallel to the lonf- axis of the car and elbows F and F
pointed" toward the opposite side of the car at its intersection with
the ceiling. The insecticide is discharged on release of carbon
dioxide by coLmpressin the tr.'gper for about 1 second. Another very
short release insures co;-plete discharge of the insecticide and pro-
vides additional turbulence within the car.


This duster provides a. simple and rapid method for the distri-
bution of insecticides. In two tests 1 ounce of 10-percent DDT dust
was distributed in refrigerator cars loaded with potatoes. The de-
posits on seven glass plates located on top of the loads ranged from
3.6 to 5.8 and from 3.5 to 4.5 micrograms of DDT per square centi-
meter, and averaged 4.7 and 4.1 micrograms, respectively. In two
other tests, in which 1/2-ounce doses were used, the ranges per
square centimeter were from 2.6 to 3.1 and from 1.8 to 2.4, and the
averages 2.9 and 2.1 micrograms, respectively. In all tests the
quantity of agglomerates deposited was negligible.

Adaptation to Use with Liquids

Preliminary trials have indicated that the duster may also be
used for distributing liquid insecticides as finely atomized sprays
if the elbows are held in position and the delivery pipes are ro-
tated one-half turn, so that the insecticide containers extend
vertically downward. The following adaptations may be made: Gas-
inlet tube K may be shortened so as to include the scoop and enough
tube to pass through pipe cap I. A tube almost as long as the in-
side length of the insecticide container may be fitted into outlet
hole J. Delivery pipes C and D may be shortened. The insecticide
container is filled with-a liquid by unscrewing the nipple L, with
the pipe cap M in place, at its junction with the pipe cap I. It
is ready for use when the nipple is screwed tightly into the pipe

- 4 -

Figure 1.--Assembled insecticide duster.



Figure 2.-Diagrammatic view of insecticide container assembly (H).

(Directions of gas streams shov.wn by arrows.)

Ill 11111HIII 11111 III R 1111111 li II 1111111
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