SI'RAYS AND OTHER MEANS OF CONTROL 



1895 



Fig. 10. !.">) A pressure regulator of a novel 

 t.vpe which effects a great savins in power, 

 prevents unnecessary wear, is positive in ac- 

 tion, and has readily accessible parts. 



at nomial speed. Hand and barrel pumps 

 should have air chambers which hold at 

 least as much as the amount of liquid 

 dispatched by the plunger per minute, 

 while twice this size is better and is not 

 too large. Traction machines need an 

 air chamber having about twice the ca- 

 pacity of the pump in gallons per minute. 

 The air chamber usually forms part of 

 the pump, but most of the traction spray- 

 ers and a few of the hand and power 

 machines have it separate. The better 

 types of air chambers are made as light 

 as possible consistent with the strength 

 required, and some provision is made for 

 agitation when the chamber is of large 

 capacity. 



Pressure Gauges 

 The pressure gauge is the index which 

 makes possible careful and exact spray- 

 ing when the remainder of the acces- 

 sories are normally good. The operators 

 of hand and barrel pumps are especially 

 liable to overestimate the pressure they 

 obtain while spraying. With hand or 

 barrel sprayers, few operators realize how 



much the pressure varies, or how much it 

 depends upon the degree of weariness 

 the operator feels toward the end of the 

 day. The work varies in thoroughness, 

 and the spray in quality, whenever the 

 pressure is allowed to run down below 

 the normal working amount. 



Relief Valvts 



Power and traction spraying machines 

 must be equijjped with a relief valve or 

 pressure regulator in order to avoid ac- 

 cidents. The poppet types of relief valves, 

 ordinarily furnished with power outfits, 

 are not suitable for use on spraying ma- 

 chines where the spraying mixture con- 

 tains grit and solid matter. When the 

 valve is raised by the pressure of the 

 liquid, it usually closes with a particle 

 of sediment lodged between the broad 

 face of the valve and its seat. This al- 

 lows the spraying liquid to escape through 

 the narrow opening at high speed, carry- 

 ing with it particles of solid matter which 

 soon channel or cut the face of the valve, 

 and it becomes leaky and inefficient. If 

 this type of relief valve had been designed 

 especially for catching and retaining sed- 

 iment, it could not serve the purpose 

 better. 



The ball relief valve has a narrow 

 seat and the ball turns, giving a much 

 greater surface with a shape whicli ob- 

 viates any serious wear. When a relief 

 valve having a small ball is used, it is 

 of small capacity and of little value, as 



Fig. n. (fl) An ciccior or jet pump of ex- 

 tremely small size hut of large capacity. A 

 simple i)lece of apparatus which lessens the 

 labor of filling the sprayer tank, especially 

 on power ouHits. 



