36 



CIRCULAR 9 7 7, U. S. DEPARTMENT OF AGRICULTURE 



In both models a vane-type air compressor weighing about 36 pounds 

 is used. This has a rated capacity of 8.3 cubic feet per minute at 

 20 p. s. i. A rubber hose extends from the compressor to a 5-gallon 

 army auxiliary gasoline can, which serves as an insecticide supply 

 tank. This tank is fitted, with a hose connection, a standpipe extend- 

 ing to the bottom, two threaded sleeves welded into the top for 

 attachments of liquid- and air-pressure gages, and a bypass regulating 

 valve. Two pieces of %-inch oil-resistant rubber hose, one for liquid 

 and the other for air, connect the tank to the spray boom. 



The spray head consists of a cluster of six air-mix nozzles attached 

 to ^-inch copper tubing (fig. 7). For a fine mist, Spraying Systems 

 unit No. 40010:120-6-35-60 is used. Larger droplets or a greater 

 range in droplet size can be obtained by replacing three or more of 

 these nozzles with nozzle unit No. 60100:140-6-5270. For residual 

 applications the coarser nozzles may be used or the spraying head can 

 be removed and replaced by a fan-type pneumatic spray nozzle. 

 With six of the finer nozzles the respective liquid flow rates with tank 

 pressures of 5, 10, and 15 pounds are approximately 8, 14, and 30 

 gallons per hour. With six of the No. 60100:140-6-5270 nozzles the 

 rates are 10, 27, and 39 gallons per hour. A pressure of 15 p. s. i. is 

 the maximum recommended in the 5-gallon auxiliary gasoline can. 

 The air line pressure is kept constant at 20 p. s. i. 



The unit as installed in a jeep weighs about 50 pounds. The 

 portable unit, including platform, wheels, and 2%-hp. motor, weighs 

 about 135 pounds. The average droplet size obtained with this 

 machine is appreciably smaller than w T ith hydraulic sprayers, and a 

 large proportion of the droplets are in the accepted aerosol range 

 (less than 50 microns in diameter). 



Figure 8.— One type of mist blower used experimentally by Army engineers. 



