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



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Figure 5. — Power hydraulic sprayer mounted in a trailer. 



A portable hydraulic sprayer (fig. 5) that is skid mounted, weighs 

 about 195 pounds, and has a piston pump operated by an air-cooled 

 gasoline engine developing 1% hp. at a speed of 2,240 r. p. m. is a 

 military-issue item (No. 9, table 4). The spray gun is furnished with 

 four disks having openings from }{& to % 4 inch in diameter. The 

 pump is required to have a minimum capacity of 3 gallons per minute 

 at a pressure of 300 p. s. i. when operating at a speed not over 150 

 r. p. m. and to have a regulator adjustable for to 500 p. s. i. A %-inch 

 intake hose is supplied to draw the spray solution from a separate 

 tank or drum. At the pressure indicated the droplets are finely broken 

 up and remain air-borne long enough to give swath widths up to 600 

 feet under favorable atmospheric conditions. Based on this width of 

 swath and an output of 3 gallons per minute of a 5-percent spray solu- 

 tion, a vehicle speed of 10 m. p. h. would give a dosage of about 0.1 

 pound of toxicant per acre, or 1 quart of solution while covering a front 

 of 72 feet. If the effective swath width is less than 600 feet, either the 

 vehicular speed can be increased or the concentration of the spray 

 reduced proportionately to give the same dosage. They can also be 

 altered to give higher or lower dosages as desired. 



Many hydraulic power sprayers are available for spraying orchards, 

 trees, and field crops. They have a wide range of weight and capacity, 

 and man}' of them are adaptable to mosquito control. Some of the 

 county or district control organizations prefer to use pressures up to 

 700 or 800 p. s. i. to produce finer mists and to carry the spray farther 

 out. 



Power pneumatic sprayers. — Pneumatic power sprayers, in which the 

 pressure for discharging the liquid is developed by means of an air 

 compressor, are also available. A lightweight pneumatic sprayer, 

 designed at the Orlando laboratory by C. N. Husman, has some special 



