LIBKAKY 
 
 STATE PLANT BOARD 
 
 August 1948 ET-260 
 
 United States Department of Agriculture 
 
 Agricultural Research Administration 
 
 Bureau of Entomology and Plant Quarantine 
 
 A CONCENTRATE SPRAYER FOR EXPERIMENTAL USE 
 
 George V. Johnson 
 Division of Truck Crop and Garden Insect Investigations 
 
 In connection with experimental work on control of the tomato fruit- 
 worm (Hellothl8 armlgera (Hbn.)) at Columbus, Ohio, a sprayer was needed 
 for the application of small measured volumes of concentrated emulsions* 
 A No* 28 DeYilbiss atomizer was modified as described herein to provide 
 good coverage of individual tomato plants in field plots with 1 to 2 ml* 
 of spray* To assist in obtaining coverage and to control spray drift, 
 the plants were covered with an adjustable cage during the spraying oper- 
 ation* 
 
 Description of Sprayer 
 
 The glass reservoir of the atomizer was replaced by a 2^- inch bottom 
 section of a test tube 3/4 inch in diameter (fig* 1,A). The test tube 
 section was attached to the metal top of the atomizer with sealing wax* 
 The liquid supply tube (B) consisted of a piece of 1/8-inch copper tub- 
 ing soldered to the metal screw top of the original glass supply tube, 
 and cut barely to clear the bottom of the test tube reservoir* A piece 
 of 3/8-inch brass tubing 8 inches long (C) was bent as indicated and a 
 hole (D) made to receive the atomizer nozzle extension rod* A piece of 
 brass tubing of a diameter to fit closely inside the air tube (C) was cut 
 about 3/4 inch long. This piece (H) was soldered in place after it had been 
 filed on one end to form four prongs* which were bent inward to make a guide 
 for the atomizer nozzle extension rod. The Junction (D) was soldered after 
 the atomizer nozzle was adjusted so that it was 1/32 to l/lt> inch in from 
 the end, and on the axis of the air tube (C). A, 3/lb-inch hole (P) was 
 bored in the air tube (C) and a piece of 1/8-inch copper tubing soldered 
 in place between the hole and the bulb end of the atomizer (&)• The br»es 
 disk (E) was soldered in place after the orifice of 7/32 inch was deter- 
 mined by trial* 
 
 Operation of Sprayer 
 
 A 2-cylinder air compressor of the paint-sprayer type* set at 17 
 pounds pressure and powered by a small gasoline engine, supplied the air 
 for spraying* An air line with a cut-off valve connected the compressor 
 and the sprayer. Air entered the sprayer at J and divided at F. Part 
 vent through the atomizer and delivered the spray at the outlet E, and the 
 remainder passed through the air tube C and joined the atomized spray at 
 the outlet. Should the orifice in the disk E be too large, or air pressure 
 
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 UNIVERSITY OF FLORIDA 
 
 3 1262 09240 9415 
 
 too low, insufficient air will "be forced through the atomizer to produce 
 the spray at E. Should the orifice "be too small, insufficient volume of 
 air will be delivered "by the sprayer to obtain good spray coverage. The 
 liquid reservoir A may be calibrated, or previously measured volumnes of 
 the emulsion may be placed therein. 
 
 Figure 1. 
 
 -Diagram of concentrate sprayer with cutaway 
 view of nozzle end.