A dust-mixing apparatus for preparing small quantities of coated or impregnated dust for laboratory use


Material Information

A dust-mixing apparatus for preparing small quantities of coated or impregnated dust for laboratory use
Physical Description:
2, 1 p. : ill. ; 27 cm.
Brindley, T.A ( Tom Albert ), 1906-
Peay, Walter E
Hinman, F. G ( Frank Gerald ), 1907-
United States -- Bureau of Entomology and Plant Quarantine
U.S. Department of Agriculture, Bureau of Entomology and Plant Quarantine
Place of Publication:
Washington, D.C
Publication Date:


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


General Note:
Caption title.
General Note:
General Note:
"January 1942."
Statement of Responsibility:
by T.A. Brindley, W.E. Peay, and F.G. Hinman.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030352426
oclc - 781870358
System ID:

Full Text

r.\ s, A -

January 1942 ET-188

United States Department of Agriculture
Bureau of Entomology and Plant Quarantine


By T. A. Brindley, W. E. Peay, and F. G. Hinman,
Division of Truck Crop and Carden Iisect Investigations

Recent developments in the use of materials containing
rotenone for insecticidal purposes indicate that in many cases
mixtures prepared from extracts of rotenone-bearing roots were
more toxic than mixtures prepared from the finely ground roots.
Existing laboratory methods of fixingn g were not satisfactory for
preparing small quantities of dust mixtures when the object was
to coat or impregnate as many particles of the carrier as possible
with the liquid extract. Most methods used to add liquid materials
to dust simply involve the addition of the liquid materials to the
carrier by pouring them in or spraying them onto the carrier as it
is being tumbled in some type of mi:er. Such r.ethcc-, often re-
sulted in mixtures in which the added liquids caused the formation
of pellets of carrier and liquid which were difficult to break up.

The apparatus shown in figure 1 seemed to overc.,.e this
difficulty to a major extent by adding the liquid in an atomized
form to a cloud of dust in a mixin- rharmber. This v,.as accomplished
through the use of the nozzle sho-'.'n in figure 2. A jacket per-
forated by a number of holes ''.'as built around a DeVilbiss atomizer.
A clou1 of dust could be blown through the perforated jacket while
a liquid was being sprayed from the atomizer. The cloud of dust
and the atomized liquid were confined in a mixing chnr-ber as shown
in figure 1. This chamber is 24 inches long and 10 inches in di-
ameter and is closed at the ends by two plates held in place by
thumb screws. The chamber is made tight by rubber gaskets.

The liquid is measured into a calibrated vial attached to
the atomizer. The dust is weighed and placed into an apparatiis for
applying dust quantitatively (described in ET-45, April 1935). Air
pressure maintained at 10 pounds per square inch was found to be
sufficient to move the dust into the mixing chamber from the uniform
dust applicator. The movement of dust and liquid into the mixing
chamber is synchronized by eye.

In order to prevent a build-up of pressure in the mixing
chamber, which prevents an even flow of the liquid materials, five
air outlets one-half inch in diameter were cut in the plate opposite


to that thrcu-h vhich the liquid and dust were introduced. These air
outlets were coverc by several la:ers of cheesecloth, which per-
mitted the esca r of excess air pressure and reduced the loss of
dust to a minimum.

The results achieved in mixing several different dust mix-
tures with this apparatus are shovn in table ,1.

Table 1.-- Check anal:. s of materials mixed in
laboratory dust-mixing apparatus

Mixed to contain Amiount actually Amount recovered,
the amount indicated, contained, based based on analyses
Field based on the on analysis made made by Division
station manufacturer's by Division of of Insecticide
sample analysis of derris In-ecticide Investigations
No. extract Investigations
e_____ lrcen{il. L_.perceni2/__ percenLt
20 0.25 0.15 0,22
25 0.25 0.15 0.17
31 0.25 0.15 0.12
22 0.50 0.31 0.29
24 0.50 0.31 0.43
30 0.50 0.31 0.34
21 0.75 0.46 0.47
26 0.75 0.46 0.47
29 0.75 0.46 0.47
19 1.00 0.61 0.74
23 1.00 0.61 0.64
28 1.00 0.61 0.62

1/ Manufacturer's analysis, 38.4 percent rotenone.
2/ Insecticide Divisior analysis, 26,5 percent rotenone.

Figure 1.-Dusting-mixing apparatus for impregnating or coating
carriers with liquid materials.


Ki l

Figure 2.-Nozzle arrangement used on dust-mixing apparatus.
This nozzle consists of a DeVilbiss atomizer with a dust
nozzle built around the atomizer outlet.


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