October 1942 ' ET-202 
 
 United States Department of Agriculture 
 
 Agricultural Research Administration 
 Bureau of Entomology and Plant Quarantine 
 
 A CONSTANT LEVELLING DEVICE FOR AN ATOMIZER TYPE SPRAYER 
 
 By Robert A. Fulton, Division of Insecticide Investigations, and 
 Charles F. Henderson, Division of Foreign Parasite Introduction 
 
 In laboratory tests with parasites of the black scale it was 
 found that the atomizer type of gun with a suction feed would not 
 deliver the spray at a uniform rate unless the liquid in the supply 
 vessel was maintained at a constant level . It was also found that 
 the rate cf delivery would alter the type of deposit on a lemon sur- 
 face. As it was necessary to standardize the procedure, a device was 
 developed to maintain the liquid at a constant level in the supply 
 vessel. The unit described herein was designed for water-soluble 
 material . 
 
 The spray gun employed was of the atomizer type with a suction 
 feed similar to the one commonly used in lacquer application. As the 
 atomizer requires a large volume of air, it was found necessary to 
 use a large diaphragm reducing valve. This type of valve is commonly 
 used by gas companies in rural service. It will maintain a constant 
 pressure for different rates of delivery, thus eliminating the necessity 
 for readjustment. 
 
 The constant levelling device is shown diagrammatically in 
 figure 1, and a general view of the combined units is shown in figure 
 2. It consists essentially of a reservoir inverted in the spray 
 vessel. The level of the liquid is maintained in the spray vessel 
 by displacement from the reservoir. In the construction of the reser- 
 voir it is necessary to use a large tube to obtain a steady flow of the 
 spray solution. The tube is cut approximately 10 degrees off the hori- 
 zontal to permit a small amount of air to enter the tube. 
 
 A flat 8-ounce bottle (A, fig. 1) was used for the reservoir, 
 to permit it to be close-coupled to the spray vessel. With this 
 arrangement, variation of the liquid level in the spray vessel when 
 
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 bubbles of air enter the reservoir through the connection tube is 
 minimized. A brass tube (D) , three-fourths of an inch outside diame- 
 ter, was soldered to the screw cap of the bottle (B) . It was 3-1/2 
 inches long, with the lower end cut at approximately 10 degrees off 
 the surface of the liquid. A brass collar (C) , approximately three- 
 fourths of an inch inside diameter and 1 inch high, was soldered to 
 the cap of the spray vessel. The collar supports the reservoir 
 bottle in a fixed position. The atomizer is connected to the spray 
 vessel by means of a compression nut (E) . 
 
 In operating the device the reservoir containing the spray 
 solution is inverted in the lid of the spray vessel. As soon as the 
 liquid in the spray vessel has reached as high as the bottom of the 
 tube a constant level will be maintained for the application. 
 
Figure 1 — Details of construction of the constant levelling 
 device. A, Reservoir; B, screw cap; C, brass collar; 
 D, brass tube; E, compression nut. 
 
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Digitized by the Internet Archive 
 in 2013 
 
 http://archive.org/details/constantlevellinOOunit 
 
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 Figure 2. — General view of the spraying apparatus. 
 
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