510 



Farm Mechanics. 



is as follows : When steam is issuing from the boiler 

 under a pressure of eighty pounds and entering the in- 

 jector at V, Fig. 248, it may have a velocity of nearly 

 1,800 feet per second; as this passes through R into S 

 it produces a strong suction in through the supply pipe 

 and when the steam strikes the cold water it is at once 

 condensed. But when the steam is condensed into water 

 it still has its high initial velocity and, striking the incom- 

 ing water, drives a portion of it directly into the mouth Y 

 through into the chamber O and from thence into the 

 boiler. 



FIG. 248.- PC nberthy injector. 



When the injector is used at a steam pressure of 65 

 pounds the water supply valve is opened one turn, then 

 the steam valve wide. If the injector does not start 

 at once, and water runs from the overflow, throttle the 

 water supply slowly until it picks up ; but if hot steam and 

 water issue from the overflow open the water supply valve 

 farther. 



