l8 SCIENCE OF SUCCESSFUL THRESHING. 



Injectors. The injector has, of late years, reached such 

 a state of perfection as to make it the most convenient of 

 all the types of boiler feeders. Although economical in 

 itself, it does not equal, in economy, a pump used in connec- 

 tion with a heater. The question naturally arises : if it be 

 economy to use a heater in connection with the pump, why 

 not with the injector as well ? Were the feed water from the 

 injector piped through the heater, but little would be gained 

 thereby, because the injector delivers water so hot, that it 

 would absorb but little additional heat during its passage 

 through the heater. Consequently, the pump, with heater, 

 is the more economical because it utilizes heat from the 

 engine exhaust (which would otherwise be wasted), to heat 

 the water, while the injector heats it by means of live steam 

 taken from the boiler. It is not usual, therefore, to pipe the 

 feed water from an injector through a heater. 



To Start the "Penberthy" Injector. With pressure under 

 sixty-five pounds, the valve in the suction pipe should be 

 opened one turn, the steam valve may then be opened wide. 

 The injector will probably start off at once, but should water 

 run from the overflow, the Auction valve should be slowly 

 throttled until it "picks up." If hot steam and water issue 

 from the overflow, the suction should be opened wider. A 

 little practice will enable one to set the valve at any pressure, 

 so that it is simply necessary to turn on the steam to start 

 the injector. At a pressure of sixty-five pounds or over, the 

 water supply valve may be opened wide, but it is better 

 partly to close it, as the injector will deliver hotter water 



