The Steam Injector
A theoretical and practical treatise on the design and operation of injectors and on the flow of fluids through and the design of nozzles.

EXHAUST STEAM INJECTORS. JO!) thau the rate of increase in velocity due to the increasecl vacuum. On the other hand, if the water supply is greatly reduced, the decrease in vacuum and consequent reduction in the velocity of the entering steam quite over- balances the advantage gained by the reduction of the load which the steam has to carry. If the water supply is insufficient, the jet will not be condensecl within the limits of the combining nozzle, and the injector will not work. Fio. 62. To improve the working of an exhaust injector it follows therefore that the vacuum at the mouth of the steam nozzle must be increased without increasing tlie< ratio of water to steam. In the injector illustrated at fig. 62 the object aforesaid has been attained by dividing the steam inlet area into two portions, one steam jet entering at a and the other at e. The whole of the water enters at f. As only a part of the steam meets the water in g, condensation is very rapid, and a vacuum of from 25 in. to 27 in. mercury is produced. The said vacuum is maintained at the supple- mentary steam inlet e. Fig. 63 is an external view of an exhaust injector of the type illustrated at fig. 62, but without the special live steam fittings there- shown. The theoretical velocity of steam (containing 20 per cent of moisture) at 16 Ibs. per square inch pressure absolute