United States Department of Agriculture
Agricultural Research AdLinistration
Bureau of Entomology and Plant Quarantine
AN IMPROVED AhMSOL NOZZLE JOR USE ON ZNGINE EXHAUSTS'
By A. N. Teoman$
Division of Control Investigations
Aerosol nossleos for use on Jeep and. airplane engine exhausts were
developed. during World War II under the Office of Scientific Research
and Developnent. This work was carried on mainly at the University of
Illinois under the direction of H. 7. Johnstone. Recently a nozzle has
been devised in this Burean which is more efficient and. more easily con-
structed than the previous nozzles and can be used on small trucks and
This typo of nozzle utilizes the heat of the exhaust to lower the
viscosity of the oil in the aerosol solution, and the velocity of the
exhaust Cases to break p the oil. The speed of the engine, the rate of
flew of the solution, and the amount of constriction at the nozzle deter-
mine the particle ssie.
The nessle is constructed of pipe fittings, and very little machining,
or special equipment, is required (fig. 1). A 1/8-inch pipe cap (A) is
first slotted on both sides with a thin hacksaw blade so that there is
3/32 inch ef metal at the center separating the slots. These slots are
made 3/16 inch from and parallel to the closed end. of the cap. The outside
of the cap it then machined down to 17/32 inch (o.&.) from the slot to the
open end and 1/2 inch (o.d.) from the slot to the closed enA with a slight
taper at each end.
The slotted cap (4) is then attached. to a 1/S-inch pipe nipple (B) 4
inches long, and a 1/S-inch pipe elbow (C) is attached. Into a 1-1/2-inch /
pipe nipple (1) 6 inches long is drilled a hole 13/32 inch in diameter
2-5/8 inches from one end. A 1/S-inch pipe nipple (D) 3 inches long is
put through this hole and attached to C. A.$ inch braze pipe nipple (G)
5/$ inch long Is then attached to a pipe reducer (7) 3* to 1-1/2 inches -
in diameter, and the reducer to the pipe nipple 3. D is then brazed to _
so that A is centered in G. Pigure 2 shows the nozzle partly assembled.
The aerosol solution can be supplied from a tank by gravity feed, by
air pressure, such as from an army type of hand-pwump sprayer, or by a
sall gear or rotary pump, V-belt driven.
The flexible hose from the solution tank is attached to the pipe
nipple D, and the open end of nipple 3 is attached to the engine exhaust.
It may be necessary to slot Z about 1 inch deep in four places and then
expand it slightly so that it will slide easily over the exhaust line,
When the exhaust outlet is a threaded pipe, the nozzle can be
attached with a regular pipe fitting. This type of nozzle is particu-
larly veil suited for tractor exhausts. It can be attached directly
over the engine by removing the muffler wad using an elbow to point the
When the nozzle is attached close to the engine, the back pressure
may be excessive. The back pressure should not be greater than 10
pounds, and the average running pressure should be between 5 and 10
pounds per square inch. A small pressure gage can be installed in the
line and a 1/2-inch gate valve used to regulate the pressure. Figure 3
shows such a nozzle and relief valve attached to the engine of a 30-
horsepover sprayer-duster. The aerosol solution in this case is supplied
by the gear pump on the machine, which is soee arranged that either the
air-blast sprayer or the aerosol nozzle can be used.
figure 4 showed the nozzle attached to the exhaust of a pick-up
truck. In an assembly of this type considerable heat is dissipated
before reaching the nozzle. For this reason the aerosol solution is
more difficult to atomize and the output should be reduced. The entire
exhaust line should be tight for this method of attachment.
To release the aerosol solution the engine speed should be as high
as can be maintained with safety. The nozzle should be allowed to heat
up for a minute or tw and the rate of flow should then be adjusted so
that no blue smoke emerges, which indicates too small a particle size.
If the flow is too great, a heavy spray io released and large particles
fall just in front of the nozzle. The rate of flow should be about 1/3
quart to 2 gallons a minute, depending on the particle size required.
This type of aerosol dispenser should be used in the same manner as
other aerosol field machines. In the field the aerosol should be released
about 1 hour after sunset on the windward side of the area to be treated.
A suitable aerosol formula contains 5 pounds of technical DDT dissolved
in 2 gallons of xylene and then in 3 gallons of 10VW motor oil.
XX''\ X X'\X\\ X\XX\
Figure l.-Exhaust aerosol nozzle.
Figure 2.-Exhaust aerosol nozzle partly assembled.
I B J
I . . . . . . . ., ,
Figure 3.-Aerosol nozzle attached to the exhaust of a 30-horsepower sprayer
duster. This photograph shows the method of attaching a pressure gage and
Figure 4.-Close-up of aerosol nozzle attached
to the exhaust of a pick-up truck.
UNIVERSITY OF FLORIDA
3 1262 09240 9779