STATE PLANT BOARD
July 1944 "T-218
United States Department of Agriculture
Agricultural Research Administration
Bureau of Entomology and Plant Quarantine
AN AIR-PRESSURE TANK FOR USE IN THE FIELD
APPLICATION OF LIQUID SPRAYS
By Floyd F. Smith, Paul H. Lung, and Anthony L, Boswell,
Division of Truck Crop and Garden Insect Investigations
The equipment and apparatus herein described meet a long-felt
need for conserving energy and time formerly expended in the hand pump-
ing of compressed-air sprayers used to apply a large number of liquid
sprays in field tests against the onion thrips and the gladiolus thrips.
For these tests, sprayers with a tank capacity of li gallons have here-
tofore been pumped by hand to about 80 pounds of pressure. With this
apparatus, a series of field treatments is applied in a single day with
less effort than was formerly required to do the work by hand over a 2-
The equipment ipcluces an air-compressor unit of standard make
provided with a 1/4-horsepower motor and an automatic cut-off belted to
a compressor, all mounted on an air-storage tank about 13 inches in
diameter and 30 inches long.
inflating tires at gasoline stations. (Fig. 2.) A valve stem from an
inner tube has been welded into the side of each spray tank near the
upper end and just to the left of the carrying handle or strap attachment.
(Fig. 3.) In this location it is above the level of the liquid in the
tanks and is not in the way of the operator when he is carrying the spray-
er in a horizontl position. After the spray material has been placed in
the tank and the pumping mechanism has been screwed into place, the air
pressure is built up .te tae desired point by applying the air hose and
checking with the pressure gauge. (Fig. 4.)
The compressor unit as mounted on skids (fig. 1) weighs about 165
pounds. It can be lifted into a truck by two men and taken to the field.
The tank, having a volume of about 2.3 cubic feet and with an initial
pressure of 160 pounds, is of sufficient capacity for applying 25 to 30
treatments with the spray equipment described above. The pressure can
be restored in about 20 minutes by driving the truck to within reach of
an electric outlet and plugging in the motor-compressor. The unit has
also been mounted Uo a two-wheeled chassis provided with motorcycle
wheels (fig. 4) for movfng the unit to various points near the laboratory.
At laboratories lacking a compressor unit, it would seem
practical to utilize amn air tank, fitted with an air valve frojn
an inner tube, which could be filled to the desired pressure at
a gasoline station. It should be equipped with a short length
of air hose and an air-valve fitting for filling the spray tanks b
with compressed air. A standard hand gauge, as used for auto-
mobile tires, could be employed for checking the pressure if a
gauge in the hose line, as described in the above equipment, is
Dr. Noale F. Howard suggested that an attachment to replace
a spark plug on an automobile may be purchased for a relatively
small sum and would serve in lieu of an air compressor. This device
would naturally be slower in building up the desired pressure.
Figure 1.-Air-compressor unit on skids as transported
in a truck.
Figure 2.--Air-hose attachment with valve fitting (A) and
control valve (B) for checking pressure-gauge
Digitized by the Internet Archive
Figure 3.-Compressed-air spray tank with an inner tube
valve located in the side just above the carrying
* ~ ~
Figure 4.--Air-compressor unit mounted on a chassis of a
two-wheeled cart. Operator building up pressure
in the spray tank.
UNIVERSITY OF FLORIDA
3 1262 09240 8839