STEAM BOILERS 333 



regulated by the valve B. In the tube C the steam is 

 combined with the slowly moving water, which is drawn 

 up from the tank D. The swiftly flowing steam puts 

 sufficient momentum into the water to carry it into the 

 boiler. The delivery tube E has a break in it at F where 

 the surplus steam or water can overflow. 



An injector should be chosen with reference to the 

 special work required of it. Some will lift water, others 

 will not. Some will start under low-pressure steam and 



STEAM 



FIG. 230 COMMERCIAL INJECTOR 



r**use to act under high, while with others the reverse is 

 tnie, There are also injectors which will operate with 

 exhaust steam. Such an injector is not essential, since 

 the efficiency of one of high pressure is practically 100 

 per cent. 



Locomotives are equipped with self-starting injectors. 



Every traction engine should be equipped with two 

 systems of boiler feeds. Some have two injectors, while 



