A duster for laboratory experiments with insecticides

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Material Information

Title:
A duster for laboratory experiments with insecticides
Physical Description:
Book
Creator:
Harries, F. H
United States -- Bureau of Entomology and Plant Quarantine
Publisher:
U.S. Department of Agriculture, Bureau of Entomology and Plant Quarantine (Washington, D.C )
Publication Date:

Record Information

Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030359336
oclc - 782911544
System ID:
AA00023133:00001

Full Text
S LIBRARY
.SATE PLANT BOARD
September 1943 ET-214
UNITED STATES DEPARTMENT OF AGRICULTURE
Agricultural Research Administration
Bureau of Entomology and Plant Quarantine
A DUSTER FOR LABORATORY EXPERIMENTS WITH INSECTICIDES

By F. H. Harries
Division of Truck Crop and Garden Insect Investigations



The apparatus shown in figure 1,A, was designed to apply small
weighed charges of dusts evenly to plants and leaves in laboratory ex-
periments with insecticides and for use in dusting the pea aphid under
controlled temperature and humidity conditions while in a natural or
undisturbed condition on the plants. The duster (fig. 1,A) consisted
of a bell Jar, an electric mixer with a variable speed transmission,
and the specially constructed parts shown in figure 1,B and C. The
funnel, or hopper (fig. 1,B), was attached rigidly to the frame of the
mixer, and the shaft (fig. 1,C) was mounted in a chuck on the vertical
drive shaft of the motor so that the metal disc would spin freely in
close contact with the lower edge of the funnel. The duster operated
by driving a dust charge from the hopper by centrifugal force through
a slight clearance space between the revolving disc and the lower edge
of the funnel, where it was finely dispersed under the bell jar and
swirled about the plant and among the leaves by the action of a small
fan.

The base for mounting the motor was made by sawing a short 2"
by 4" piece of lumber in half longitudinally and fitting and bolting
the two pieces of wood tightly together around the neck of the bell
Jar. The motor was placed over a pad of sponge rubber to prevent ex-
cessive vibration and was held in place by bands cut from the inner
tube of an automobile tire. The funnel, or hopper (fig. 1,B), was
made from a bakelite spark plug cover by cutting out the closed end
and was cemented inside a metal collar and attached to the frame of
the mixer by small metal brackets. The shaft (fig. 1,C) was made by
machining and cutting threads on a short piece of brazing rod. The
disc was made of sheet copper about 0.04 inch in thickness. The fan
was constructed from a disc of the same material by cutting in from
the edge toward the center at 45-degree intervals and twisting the
sections at a 45-degree angle with the original plane. The disc and
fan were mounted in the desired position on the shaft by means of thin
lock nuts. Rubber washers were used on each side of the disc to give
some flexibility in its mounting on the shaft. When the shaft was
fastened in the chuck of the mixer, emery powder was used to grind the
lower edge of the funnel smoothly in the same plane as that of the disc
so that the latter part would revolve freely in close contact with the
hopper. To prevent dust from collecting in the neck of the bell jar,







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this space was closed off by a gasket of cork or sponge rubber fitted
around the lower part of the funnel (fig. 1,A). Tufts from a camel's-
hair brush were cemented to the lower side of the disc to sweep the op-
posite surface of the glass and prevent dust from collecting at this
point as it was thrown from the lower edge of the dust hopper.

The speed of the disc and fan was regulated near the maximum rate
of 3,500 r.p.m. by raising the horizontal wheel of the transmission to a
level near the outer edge of the vertical wheel (fig. 1,A). The rate of
distribution of the dust was controlled by moving the adjustment screw
very slightly to regulate the amount of clearance space between the disc
and lower edge of the dust hopper.

In use the duster was placed over an infested plant, and a weighed
charge, usually of 50 or 100 mag. of dust, was transferred to the hopper
and brushed cleanly to the bottom with a small camel's-hair brush. With
the aid of a stop watch and an interval timer the duster was operated for
30 seconds to distribute the dust and then was left in position for an
additional period of 3 minutes to permit most of the dust to settle down.






























MOTOR
SPONGE-RUBBER PAD
WOODEN
BLOCK
RUBBER BANDS



G







DUST
HOPPER









LOCK NUT
RUBBER WASHER-"


BRACKET

COLLAR


K FUNNEL



SSHAFT




| DISC





FA N
NUT

C


WOODEN
PANEL


Figure 1,-Diagram of duster showing details of construction.


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