STATE PLANT BOARD
October 1944 ET-21
ITNITID STATES DEPARTMENT OF AGRICTLTUiRZ
Agricultural Research Administration
Bureau of Entomology and Plant Qarantine
INJECTOR FOR FUMIGANTS IN LIQUID FORM
By R. D. Chisholm, Division of Insecticide Investigations,
and V. C. Pest and A. C. Mason,
Division of Fruit Insect Investigations
Many devices have been described for the application, for particular
purposes, of measured doses of fuaigants which are liquids under ordinary
conditions of temperature and pressure. This paper describes an injector
which has been found to be useful for the injection into corrugated paper
cartons of doses of ethylene dichloride ranging in volume from 1 ml. to
21 ml. in steps of 0.9 ml. The cartons contained plant material infested
with Japanese beetle larvae.
Description of Apparatus
The injector can best be described by referring to the lettered parts
in the drawing (figure 1). The barrel (A) is a piece of extra heavy brass
pipe reamed to a convenient uniform diameter and of the desired length. The
piston (B) is made from a piece of round brass rod machined to a diameter and
to a length which are both slightly less than the diameter of barrel (A). A
groove (C) is provided in piston (B) to accomodate a closely fitted packing
ring lubricated with graphite. Piston (B) is moved by means of screw (D), the
lower end of which is recessed to rotate in split-bushing (Z), which is screwed
into a hole drilled in the upper end of piston (B). Split-bushing (E) is made
from hexagon-shaped brakes rod. The rod is halved vertically. The halves are
placed together and drilled to accommodate the recessed end of screw (D). With
the exception of 1/8 inch, the outside of the halves are then machined and
threaded to screw into the hole in piston (B). All parts are fitted closely
to reduce lost motion when screw (D) is rotated. Screw (D) extends through
a threaded hole in flanged plug (FT which is screwed tightly into the end
of barrel (A). A small-bore tube (0) is fitted in flanged plug (H), which
is screwed tightly against a paper gasket resting on the lower end of barrel
(A). Screw (D) is rotated by means of crank (I). The top of flanged plug
(Y) is graduated in convenient units. Barrel TA) is provided with a vent (J).
The injector is filled by placing the tip of tubs (G) below the surface
of the liould fumigant and rotating screw (D) in a counterclockwise direction.
The fumigant is discharged by rotating screw (D) in a clockwise direction.
The injector is calibrated by dividing the volume per unit length of barrel
by the number of threads per unit length of screw, or by measurement of the
volume of fumigant actually discharged during each rotation of the screw.
Uses for Apparatus ..
The injector has been found to be suitable for the application of
ethylene dichloride for Japanese beetle quarantine purposes. The barrel b
of the injector used was 5 inches long and had an inside diameter of 1-1/16
inches and a screw with 14 threads per inch. The delivery of ethylene di-
chloride per rotation of the screw was calculated to be l.04 ml. Twenty
rotations of the screw delivered 21 ml. or an excess of 0.01 ml. per rota-
tion. Fractions of a milliliter are delivered by partial rotation of the
screw regulated in reference to the pointed end of the crank and the gradu-
ations on the top of the upper flanged plug.
By selecting the proper barrel diameter and screw pitch the injector
may be constructed to deliver other measured doses for a variety of purposes
such as soil injections.
UNIVERSITY OF FLORIDA
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