October 1947 SAT pL 4T ET-246
United States Department of Agriculture
Agricultural Research Administration
Bureau of Entomology and Plant Quarantine
A GLASS CONTAINER FOR USE IN STUDYING AEROSOL SOLUTIONS
R. A. Fulton and F. I-). - i
Division of Insecticide Investigations
The preparation of liquefied-gas aerosols for experimental purposes
requires special equipment for the handling of liquids under a gage
pressure of 15 to 85 pounds per square inch. It is highly desirable to
be able to observe the solution for the presence of insoluble material
and for the study of physical and chemical changes in the solution. A
number of devices have been described for this purpose, but all have the
disadvantage of excessive weight (300-350 grams) of the container in
proportion to the weight of the liquid contents (10 grams). A glass
container has been developed which weighs approximately 400 grams and
has a capacity of 350 grams of the aerosol solution.
The container (fig. 1) was constructed from a strong glass bottle,
of the kind commonly used in the drug-store trade for citrate of magnesia,
and a refrigeration Y valve (&) with 3/8-inch male and 1/8-inch female
outlets. The male connection of the Y valve was machined on a turning
lathe to the same shape as the glass stopper furnished with the bottle.
The end of the valve, H was then drilled so that a 1/4-inch (o.d.)
stainless steel tube (45 could be soldered into it. It was necessary to
notch the Y valve at D to hold the wire loop directly in position over
the center of the bottle and to produce an even pressure on the gasket (j).
The gaskets were made from 1/8-inch sheets of neoprene or a polyvinyl
alcohol resinous material. The neoprene material is suitable for use with
the solvents in most of the aerosol formulas, but with the chlorinated
solvents it is necessary to use polyvinyl alcohol sheet stock.
For filling the containers with the aerosol solution, two methods are
used in the laboratory. The first method is similar to the procedure
commonly used in filling the steel containers. The bottle is washed and
dried, and the valve assembly is placed in the neckj where it is fastened
by a lever (E). A brass flared fitting (1/8-inch IPT to 1/4-inch SAS)
is attached to the valve at j. The bottle is then connected to a vacuum
pump to permit filling by vacuum. The insecticidal materials are dissolved
in the solvents to be used in the aerosol, and the solution is drawn into
the bottle through a 1/4-inch copper tube with a 200-mesh screen on the
end. The bottle is then connected by means of a refrigeration hose to a
supply of Freon-12 (dichlorodifluoromethane) or a mixture of this gas with
Freon-ll (trichlorofluoromethane). 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 the propellent gas to be added are then placed
on the balance pan. The Y valve is opened to allow the propellent gas to
flow from the reservoir, and closed when the calculated amount has been
added. The tank is disconnected and the flared union is replaced with
a nozzle tip (A). The use of electric solenoid valves for filling
aerosol containers has been described elsewhere W).
The second method is used for filling the containers where the
final pressure of the liquid is under 50 pounds per square inch. The
weighed ingredients are placed in the dried bottle, which is then
weighed. The propellent gas is then cooled in a coil of copper tubing
packed in dry ice. The cooled liquid is slowly aided to the bottle until
the desired weight has been reached. The valve assembly is placed in the
bottle and fastened with the lever. The filled bottle is then allowed to
come to room temperature. It may be necessary to warm the bottle to
dissolve the insecticide.
The type of bottle used will withstand safely pressure up to 85
pounds pez square inch. The bottles have been tested to 200 pounds per
square inch with no failures. At higher pressure the valve-locking device
will bend slightly, releasing the pressure within the bottle. As a
precautionary measure, a safety glass screen should be used when the
filled bottles are being handled on stone-top desks.
(1) Fulton, R. A., Berlin, F. D., and Bochert, Ro S., Jr.
1947. A laboratory method for filling aerosol containers.
U. S. Bur. Ent. and Plant Quar. ZT-245. 24 pp.
I -A -G
Figure 1.--Diagram off glass aerosol container (left) including
detail off Y valve (right).
UNIVERSITY OF FLORIDA
II llI l lJ 11 111111111 1111 1111111111111 1II l1 l
3 1262 09240 9688