May 1%7 Er-238 United Stetet Dtpartuent of i^rlculttire i^rlciatural fiasearch Adolnlstration Bureau of Sntonolofy axid Plant ^Liarantlne AS iOCEAUST ASBOSOL aXHXBlTOH TOR 1-1 /2-eOfiSEPOWE£ MOTOBS By A* H, Yeomans and W. 0. Bodenateln DlTlslon of Control InTeati^atlons Attaohments uting the ezhauet of gasoline motors for producing aerosols were used effectively on Jeep and airplane engines for aosquito and fly control vork by the iaerican nllitary forces during World War II. The particle sise of aerosols pro- duced by this method depends on the speed of the engine and on the rate of flow, viscosity, and other physical characteristics of the insecticide solution* An exhaust aerosol generator has been constructed to be used on a 1-1/2 horsepower, U->cycle gasoline motor. The cost of material and brazing, in addition to the motor, is estimatsd to be less than $^. The apparatus can be modified slightly for use on larger motors \9 to 20 horsepower. This method of producing an aerosol is economical if the motor is already on hand« This apparatus can be used for killing flies and any other pests for which the aerosol bomb is used. The aachine can be used in bams, greenhouses, warehouses, and houses, and under canopies in the field. It is not suitable for dispersing water suspensions unless small quantities are used, bat most oil solutions can be used in the machine. The carbon monoxide fumes build up with extended use of the machine in confined spaces, but for the usual time in applying insecticides the carbon monoxide is not objectionable* A Briggs and Stratton motor has been used with the goremor set for a speed of 2,^0 r.p.m. The higher the speed the smaller the particle size. To break \xp the insecticide solution the oil is released into the exhaust gas as the gas escapes between the 3/l6Minch diameter tube for the oil and the 1/U-inch diameter hole in the pipe cap. This opening is 0.02lU square inch, which is sufficient to allow the engine to be run with a back pressure of only about >*l/2 pounds per square inch. - 2 - The flow of oil control! the particle size, and for ordinary fly Bpraye the flow should "be about U liters per ho\ir. This flow can be easily regulated by using a small opening in the oil line. On this machine the opening is 0.033 inch in diameter. When deodorized-kerosene standard fly sprays are used, this flow rate gives an arerage particle diameter of about 15 microns. The equipment required for this apparatus, in addition to the motor, is as follows: Three l/2-inoh p^enipples - one 2-1/2 inches, one 3-1/2 inches, and one 5-1/2 inches long; two l/2«inch pipe caps; one 1/2-inch pipe tee; a piece of 3/l6-inch (o.d.) copper tubing about 3 inches long; one half-Ainion braes coupling with a 1/2-inch tube flare at one end and a 1/8- inch pipe thread at the other end; one 1/8-inch pipe ralre; two 1/8-inch pipe fittings; and a discarded aerosol bomb. Figure 1 shows the complete assembly with the machine in operation. Figure 2 shows a close-up of the nozzle. Figure 3 shows the cross section through the nozzle. Construction of the apparatus (fig, l) consists in attaching the 2-1/2-inch pipe nipple (D) to the engine, the pipe tee (C) to r with the tee upward, and then the 5-1/2-inch nipple (E) to the top of C, with a pipe cap (J) on top. In a y-l/Z^inch nipple (B) a hole 1 inch from one end is bored with a 7/32- inch drill. One end of a 3-inch length of 3-1/l^inch copper tubixig (H), bent as shown in figure 3* ^b inserted into this hole so that it protrudes slightly, and the other end extends 1 inch beyond B. In the center of pipe cap (A) is drilled a 1/U-inch diameter hole. As is further illustrated in figtire 3* & half-union brass coupling (I,) with a 1/2- inch tube flare to a 1/8-inch thread, is put orer the end of H, with the thread at the top, and then brazed so that I^ is con- nected to H and H to the pipe B. A brass disk (not shown) perforated with a 0,0J5-lnch diameter hole is placed on the 1/8-inch pipe fitting (I) , and a valve ( &) is then attached. The cap A is then tightened to the nipple B so that the tube H projects through the hole. The tube is then marked, the cap removed, and the tube cut so that it extends only to the inside edge of the l/^inch hole. Cap A is then replaced, completing the nozzle. With these fittings completed, B is attached to pipe tee C. The discarded aerosol bomb (J) is converted into the container by drilling a 1/2-inch diameter hole in the base for filling, and a 1/Uw-lnch diameter hole into the tapered end, removing the tube, and brazing on a l/8-inch pipe fitting (L). The bomb is then attached to the valve £, and the machine is ready for operation. -3 - Th« DOtor thOTild b« run for 2 alnutet to boat it tip before the Insecticide solution is run through. The aerosol should appear white, and in a dosed rooa should remain air-home for more than 30 minutes* If a bluish aerosol is produced, the machine is too hot and the warm-up time should be cut down. If the liquid drips from the noscle ezcesslrely, the wani»^ch o.d. copper tubing is used for the oil line are as follows t Motor Horsepower Diameter of Outlet Opening in Inches 1-1/2 0.250 (l/U) 3-5 .266 (17/61^) 5-10 .297 il3l&^) 10-15 .313 (5/16) 15-20 .3^4 (11/32) Tor the larger motors the flow of oil should be increased in proportion to the horsepower. I'or motors larger than 1-1/2 horsepower, an ordinary ralre without the use of the capillary disk is sufficient to control the oil flow. A flexible metal tubing can be used between the oil tank and the outlet opening. - u Figure 1. — Assemblj of l-l/^-horsepower gasoline-engine exhaust aeroeoL generator. - 5 Figure 2.— Details of noBsle of •xbmist aerofol generator for use with l-l/2-horsepo«er gasoliae aotor. - 6 - UNIVERSITY OF FLORIDA iillilllllitllllillPIII 3 1262 09240 3855 BRAZE 1/8 PIPE THREAD H" 3/16 O.D. TUBING 1/2 PIPE-^ "B" 3-1/2" NIPPLE 1/4" D. HOLE Figure 3» — Cross section through nozzle.