314 CONTROLLING INSECTS AND DISEASES 



3-horsepower engines. Their capacity is from 6 to 10 gallons 

 per minute. They will carry one lead of hose and rod with 

 three nozzles maintaining a pressure of 400 pounds. This type 

 of machine will care for upward of 5 to 10 acres of orchard, 

 the determining factor being sufficient time to get the spray 

 on during the period of effective control. 



Three- and four-cylinder pumps deliver 15, 35, and as much 

 as 50 gallons per minute. They are driven by 5- to 25-horse- 



power engines or by a 

 power take-off from the 

 tractor. Larger outfits will 

 carry two lines of hose with 

 6 and 8 nozzles on each and 

 still maintain a pressure of 

 600 and 700 pounds. The 

 grower must decide whether 

 he is to use one large out- 

 fit or more smaller ones. 



(a) Pump Specifications. 

 The pump design should be 

 simple with all parts easily 

 accessible. Parts subject to 

 wear should be so designed 

 and located that they can 

 (John Bean Mfg. Oo.) be quickly replaced. Many 

 Fig. 106. The ball valve gives long spray materials are corro- 

 wear without leakage. sive. Parts in contact with 



them are usually of porce- 

 lain or brass. Valves of the ball type, made of stainless steel, 

 with seats that are quickly replaceable, give greatest satisfac- 

 tion (Fig. 106) . Poppet and disk valves do not wear as evenly as 

 ball valves, and leakage becomes a serious problem with 

 them. 



Pump cylinders (Figs. 107 and 108), are of brass, porce- 

 lain, or steel, the steel ones being intended for quick and ready 

 replacement. The plunger within the cylinder may be of an 



