3T;.A^ l.-:.,i )ARD
July 1949 ET-273
United States Department of Agriculture
Agricultural Research Administration
Bureau of Entomology and Plant Quarantine
, AN IMPROVED APPARATUS FOR OBSERVING AEROSOL SOLUTIONS
AND DETERMINING FREON-INSOLUBLE MATTER IN
By R. A. Fulton
Division of Insecticide Investigations
A glass container for studying aerosol solutions and the method of
filling it were described by Fulton et al. in 1947 (1, 2). This container
was later modified by Hazen and Fulton (3) for the determination of
Freon-insoluble matter in pyrethrum extract. The apparatus has since
been improved to withstand higher pressures and to provide the operator
with protection while handling the individual units.
Description of Apparatus
The apparatus shown in figure 1 was constructed from a strong glass
bottle, commonly used in the drugstore trade for citrate of magnesia,
with a special pressure cap and needle valve. The cap (C), which is
held tightly on the bottle by an adjustable frame provided with a tight-
ening screw (E), was constructed from 1 1/4-inch round brass stock by
machining on a turning lathe to the same shape as the glass stopper fur-
nished with the bottle. The lower end of the cap was then drilled to a
depth of 1 1/4 inches with a 3/16-inch drill and then at right angles on
the side for the outlet to the valve. The lower end of the cap was then
drilled to a depth of 3/16 inch with a 5/16-inch drill. This opening was
threaded on the lathe to a 13/32-inch by 36 thread to fit the filter-screen
unit (B) commonly used on oil-burner tips. The side outlet was drilled
to a depth of 3/8 inch with a 5/16-inch drill and threaded with a 1/8-inch
pipe tap. A depression was made in the center of the top of the cap to
hold a 3/8-inch ball bearing (D).
The frame (A) for the bottle was constructed from two 3/8-inch steel
rods threaded on both ends. The upper end of each rod was threaded for
a distance of 2 inches to permit adjustment of the crossbar for irregular
shaped bottles. The crossbar was made from 1/2- by 1 1/4-inch brass
stock and drilled with two 3/8-inch holes 2 inches apart. The pressure
screw hole was then made with a 5/16-inch drill and threaded with a 3/8-
inch tap. The end of the pressure screw was recessed with a 3/8-inch
drill to hold the ball bearing. The base for the frame (J) was made
from 4-inch round brass stock. After a 1/2-inch section had been cut
from the brass stock, a depression was made in the center 3/16 inch
deep and 2 3/4 inches in diameter to hold the bottom of the bottle in
place. A 2 3/4-inch disk was cut from a 1/8-inch rubber stock to serve
as a cushion between the bottom of the bottle and the brass base. Two
5- 6-inch holes were then drilled diametrically opposite in the base and
threaded with a 3/8-inch tap. The steel rods were heated to a cherry red
-nJd bent in the shape shown in figure 1. The correct adjustment of the
l'.izht of the crossbar was then made by placing the bottle in the frame
d turning the lock nuts to obtain sufficient clearance for removing the
bottle. The ball bearing was used to obtain uniform pressure on the
neoprene washer in the top of the bottle. The safety shield (F) was
rmrde, by cutting a 7-inch section from 3 3/4-inch Lucite tubing. By
cutting a notch (H) in the tubing 1 1/2 inches deep, it was possible to
odiust the needle valve (G) and still have the shield extend above the
level of the bottle for maximum protection.
How Apparatus is Used
When the apparatus is being used for the determination of Freon-
insoluble matter in pyrethrum extract, the filter unit (B) filled with
lamb's wool is attached to the pressure cap (C) as shown. Prior to use
the pressure cap and filter unit are washed with acetone and chloroform.
The bottle is then cleaned with a 1:9 mixture of ethyl alcohol and sulfuric
acid, and later rinsed several times with distilled water. All parts are
dried in an oven at 105 C. for 1 hour and then cooled in a desiccator.
After the insecticide material dissolved in suitable solvents has been
placed in the bottle, the apparatus is assembled as shown in figure 1.
The unit is evacuated and then connected by a refrigeration hose to a
supply of Freon-12 (dichlorodifluoromethane). The tank valve is opened
to fill the hose with the liquefied gas. The bottle is weighed and additional
weights equivalent to the amount of propellent gas to be added are then
placed on the balance pan. The needle valve (G) on the bottle is opened
to allow the Freon to flow from the reservoir and closed when the cal-
culated amount has been added.
The frame and pressure cap may be used with different-shaped
battles, such as those used in the carbonated beverage trade. The
citrate of magnesia bottles will withstand safely pressure up to 200
pounds per square inch, but any glass under continuous strain will
fatigue. It is suggested as a precautionary measure that bottles allowed
to stand for any period be kept behind a safety-glass screen.
(1) Fulton, R. A., and Berlin, F. D.
1947. A glass container for use in studying aerosol solutions.
U. S. Bur. Ent. and Plant Quar. ET-246. 3 pp. LProcessedj
(2) ____ Berlin, F. D., and Bochert, R. S., Jr.
1947. A laboratory method for filling aerosol containers.
U. S. Bur. Ent. and Plant Quar. ET-245. 4 pp. Processed.
(3) Hazen, A. C., and Fulton, R. A.
1948. A method for the determination
in pyrethrum extracts. U. S.
ET-257. 4 pp. LProcessed7
13/32" Diom., /
36 threads per-, /
(See text for explanation)
of Freon-insoluble matter
Bur. Ent. and Plant Quar.
Figure 1.--Apparatus for observing aerosol solutions and determining
Freon-insoluble matter in pyrethrum extract, showing arrangements
of integral parts. See text for explanation of letters.
UNIVERSITY OF FLORIDA
3 1262 09242 9033