^^.^ PLANT I June 1949 ET-269 STATE PLANT BOAKu; United States Department of Agriculture Agricultural Besearch Administration Bureau of Xntomology ajxd Plant Qiaarantine AUTOUAIIC INSECTICIDB-DISPENSINa EQPIHiENT yOE INSTALLAIION IN AIECEAPT Sy A. H. Yeomene and W. N. Sullivan, Jr., Diylsion of Control Investigations, and E. A, Tulton, Division of Insecticide Investigations Aircraft flown over long distances creates a hazard of insect dissemi- nation that is causing great concern. Adult insects are commonly found In airplane interiors when the planes are ready for the take-off to distant points, and if not destroyed or removed they will "be transported to new areas within a matter of hours. Several instances of insects "becoming well esta'blished in locations far removed from their previous known halDltat have been reported recently* It is iinpractlcal to keep Insects out of grounded airplanes. Attention has long been focused on means of destroying the insects and so preventing the transport of live forms, A combination of an aerosol (space spray) and a residual spray appears to be the most satisfactory insectlcidal treatment. Two procedures are now in common use for applying aerosols — namely, treat- ing before take-off and by crew members during flight. Aerosols dispensed from hand containers have been used extensively on both commercial and military airplanes. When aerosols are so dispensed by different persons under various conditions, the dosage varies and the distri- bution is erratic. To overcome these disadvantages, automatic dispensing equipment that will apply a measured dosage and assure uniform distribution has been proposed. An automatic device for releasing liquefied-gas aerosols has been developed, ihlch has passed Initial experimental trials, Hecently, arrangements were made throu^ the Department of the Air Force to install this apparatus In IHlltary Air Transport Service planes at Beltsvllle and in Hawaii, to provide opeirational tests, WorkBrs in Sngland (Uackle and Crabtree l) developed and tested an apparatus designed for this use as early as 193^* ^^ ^^^ American Sanitary Bureau (Snow g) In cooperation with the U. S. Navy, the Public Health Service, and the -Boreau of Entomology and Plant Quarantine began work on apparatus several years ago, and later installed it in a Navy aircraft,^ This device was used because of its simplicity, li^t weight, and efficiency in producing the desired range of particle sizes. 1/ Hirst, John M. Preliminary report on development of apparatus for aircraft disinsection. (Unpublished) U. S. Naval Air Station, Patuzent, Ud, - 2 - Description of ipparatus Supply Tank .— A standard portable aircraft ojcygen cylinder of lOU cubic inches capacity serves as the aerosol supply tank. This cylinder is of convenient size, and is easily refilled. It is ottainalble in stain- less or hlgh-caxton steel, is nonshatterahle, and will withstand internal pressures well a'bove UOO pounds per square inch. The tank is equipped with an eduction tube. Solenoid Valves .-— Standard light-weight, S^Hvol^ d.c, aircraft sole- noid valves equipped with aromatic Heoprene on the face of the plungers are used at each point of release. The valves are connected to the manifold on the inlet side and to the nozzles on the outlet side. All the sole- noids ai'e wired to a central timing switch so that all are actuated simul- taneously. A lOO-mesh filter screen is placed on the inlet side of each valve to prevent improper seating or clogging of the nozzle due to foreign matter. The valves have a power consumption of ahout 6 watts, and with- stand pxressures ahove 200 pounds per square inch. Hozzles .— Capillaries are used as nozzles. Typical nozzles have capillaries between 0.09 and 2.0 inches in length with the diameter of the bore ranging between 0.010 and 0.020 inch. Owing to drilling difficiil- ties capillaries longer than 0.1 inch are made of prefoxned cc^illary tubing brazed or soldered to a threaded base. The capillary length can be extended with a threaded pin pushed into the smooth throat of the nozzle, the grooves in the threads being used for the c^illary. The space between the base of the capillary and the valve seat is kept to a minimum to prevent dripping when the valve is shut off. A screen with mesh slightly smaller than the nozzle orifice, and with at least 30 open- ings through which the solution can flow, is fitted in the base of the nozzle. Uultiple nozzles are made with two or more c^illaries to allow release in several directions. The particle size of the aerosol produced has been found to be a function of the length of the capillary, the size of the orifice, the vis- cosity of the liquid, the percentage of nonvolatile material, and the pres- sure. It was therefore necessary to modify the nozzles to give a satisfac- tory discharge rate and particle-size distribution for every formula. Manifold , or Tubing , System .— Soft aluminum tubing, 3/16 inch o.d., has been used in one aircraft installation. It is li^t in weight, resist- ant to chemical reaction with any of the ingredients used, withstands the pressure of the liquefied gas in the system, and maintains tight connections at the unions. Check valves and closed valves are not Included in the system except at the supply cylinder. The valves at the supply cylinder are opened as soon as it is attached; otherwise the hydraulic pressure created by hi^ temperature would create abnormal pressure in the manifold. The tubing is cleaned of all dust and dirt before being inetalled. It is fastened in place by Adel clamps and is protected by grommets where it passes thro\igh bulkheads. Soft copper tubing 3/16 inch o.d, was used in one installation for test purposes. Stainless steel tubing is now being - 3 - tested for posei'ble use in the nanifold system. All fittlsgs are of the flared-tuhe type, of Dural metal eqiiipped with eleeres* fhe eystea was ohedced for leaks after each installation. Back- seat in^* light-veight , hand-operated ralTes are used on the supply tank and on the connecting end of the manifold system. This type of valTe pre- Teats leakage aaround the ralye stems when the system is in use, A hand- operated coupling unit is used 1>etween the supply-tank Talre and the mani- fold Talre to permit rapid changing of the supply tank. This coupling unit is fitted with an aroiatic Neopirene washer, which will resist the effect of the aerosol solution. All pipe threads in the Installation connections are 1/8 inch. The pipe-thread connections are sealed with thread-8eatia|( ccna- pound cqpplied after the threads are started (to prevent the compound froa entering the manifold tuhlng). Timing Switch , — The dosage is measured hy time. The output of a set of nozzles is detexnined for a given solution under a given pressure. The total dosage necessary for an airplane of given capacity divided tjj the eom'bined output per second determines the length of time the valves shall remain open, A mechanical timing switch commonly used in photographic laboratories is used to measure this time Interval, The operator turns the indicator of this switch to a predetermined setting hefore releasing the aerosol. The solenoid valves open when the switch is released and remain open until the switch indicator returns to zero. With this indicator the time interval can "be changed if it is necessary to change the dosage. The current is connected to the electrical system of the aircraft. The mani- fold system is protected with a ^'"eaapere circuit-breaker switch for safety, A single-wire system is used, each solenoid being grounded to the airplane frame. Typical Installation The manner in which the automatic insecticide-dispensing equipment is installed varies with the airplane, A typical installation, the eq^uipment placed on a Military Air Transport Service plane at Honol\ilu in January 19^9. will be described below. The supply tank was located near the center of the passenger compartment about 20 feet from the front bulMxead, and fastened on the blanket rack on the right side, A wide aluminum band attached to the blanket rack held the tank in place, A back-seating valve was placed on the connecting end of the manifold system to prevent the line from draining when the supply tank was changed, A quick covpleT connected this valve with the valve on the supply tank. The aluminum tubing of the manifold system was attached to the fuse- lage along the top of the blanket rack. The tubing to the two other sole- noids beyond the blanket rack was hell ti^t against the fuselage with Adel clamps placed at frequent intervals. The four points of release were as follows: (a) In the toilet above the wash-basin mirror, a single-angled outlet nozzle pointing toward the rear; (b) in the passenger coE^artment on the front of the blanket rack, 13 feet k inches from the front bulMiead, a double-angled outlet nozzle point- ing front and rear (fig, l); (c) same as preceding, but located 26 feet 8 inches from the front bulkhead; and (d) in the rear of crew's compartment LIBRARY -u - on the door frame with a single-outlet nozzle pointing forward into center of aisle (fig. 2)* The 2U-^olt power was taken from the circuit "box located in the food conpartment at the rear of the fuselage, connected hy a single wire in series to a 5-eaiper© circuit-hreaker switch, then to the timing switch located over the food compartment entrance (fig. 3). From the timing switch the single-wire circuit was connected to the four solenoids. Each solenoid was grounded to the frame to complete the circuit. The nozzles were designed spaoifically for use with formulas contain- ing Oenetron-lOO (ethylideno fluoride) and Frecn-lS (difluorodichlorometh- ane) as the propellent gas and had c^illaries 0.09 indi long with orifice diameter of O.O17 inch (fig. U) • With formula G-575 (pyrethrum extract 5, piperonyl hut oxide 2, DDT 3, cycloheiajione 5. and luhricating oil (No. 10) 1 percent in a 1:3 ^aixture of Genet ron-lOO and 2'reon-12) the output of each outlet was l.b grams per second at 90 pounds per square inch. The particles had a median mass diameter between 15 and 18 microns and a maxiBom diameter of hO to ^0 microns. Th6 weight of the equipment was U pounds for the filled supply tank and I+.65 pounds (2115 grams) for the rest of the system, apportioned as follows: Grams Grams Aluainaa tuhing 3S0 Backseat ing valve and coupler 25O |^ Solenoids 680 , Quick coapler 70 -^ Timer 25O §// Pittings 120 ^^ fire 300 ^ Nozzles o . . . . b5 -^ The equipment was as follows: 1. Supply tank. MSA "breathing oxygen cylinder, Tj^pe A^Spec. 9H-I40376. 2. Two mechanical valves. Back-seating type, l/l^inch male pipe to l/l^-inch flared tuhe. (Calumet Angle Valve 213^ or equal.) 3. Quick coupler. l/U-inch female flared tahe to lA-inch female flared tube. (Superior or equal.) l^, Aluminum tubing 3/?.6 inch o.d,, six 12-foot lengths. 5. nttings, flared tube, all fitted with nuts (Parker AN 8I8-3 Dural) and sleeves (Parker M 819-3 Dural): (a) 90« angle l/8-inch pipe to 3/16-inch flared tube (Parker AN 822-3 Dural) for rear solenoid. 2/ These weights can be reduced in faturo installations by use of certain alloys. - 5 - ("b) Connections » 3/l6-lnch to 3/l6-inch flared tu"bo (Pfirker 3 HT Dural), two required to connect 12-foot lengths of tubing in food compartment and in forward end of passenger com- partments. (c) Tees, 3/l6-inch to 3/l6-inch to 3/16-inch flared tuhe (Parker M g2U-3 IXxral), three required for outlets to ^pplj tank and solenoids in passenger compaxtment • (d) Connections, 3/16-inch flared tube to l/8-inch pipe (Parker M 816-3 I>iral) , four required, three forward solenoids and one at mechanical valve* (e) Brass coupling 1/U-inch pipe to l/U-inch pipe with "brass reducer l/l|— inch to l/S-inch pipe. To "be soldered to "back- seating valve on end of manifold line* 6. Timing switch (Mark Time model UgoMHiP or equal)* 7* Wire, 7-strand No. 20 low-tnnsion aircraft type with spaghetti coverings, 65 feet. S. Adel clamps, sheet-metal screws* 9* Solenoid valves with aromatic Heoprene plungers (Adel No* 12237''28, 2^ volt or equal )f four needed. 10* Pour nozzles (outlets depending on type of aircraft)* 11. Filler plug in outlet side of solenoid valves* (Pig* k,) 12* Screens cut circular to 0*3^0 inch diameter with holes 0*01 inch in diameter (JelliffU Lectromesh ^0-mesh screen or equal). Insert 3/8-inch disk into each outlet side of solenoid valves* 13* Aluminum brackets for solenoid valves* Literature Cited (1) Hackle, F* P., and Crabtree, H. S* 193d. The destruction of mosquitoes in aircraft. Lancet, Aug. 20, p. M7. (2) Snow, Donald L. 19^5 • A preliminary report of the development of equipment for the autoaatic disinsection of airplanes. Pan American Sanitary Bureau, Aug* I5. /ProceBae^J, 6 - Figure 1. — ^Automatic insecticide-dispensing equipment in operation in a C-54^ airplane passenger compartment. Figure 2. — Installation of solenoid valve and nozzle in the crew's com- partment of a C-^/^ airplane. Digitized by the Internet Archive in 2013 http://archive.org/details/automaticinsectiOOunit - 7 3 8. rr N O +» 01 a si IS to 8 • •do o o H ait £7 E UNIVERSITY OF FLORIDA 3 1262 09240 9720