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.

 30 THE STEAM INJECTOR. exit and the throat of the delivery nozzle is generally from 15 to 24 times the diameter of the throat of the delivery nozzle. It will be understood that the liotter the feed water and the higher tlie temperature of tlie steam, the longer will it take to effect complete condensation of the steam. It would appear to be possible to vary tlie length. of the combining nozzle within fairly wide limits without veiy materially affecting tlie efficiency of the injector. Injec- tors have been tried with the length of the combining nozzle only four times the diameter of the delivery nozzle throat. The jet from the combining nozzle will, however, be given greater stability if passeel through a nozzle of greater length. It is impossible to calculate the exact length of nozzle required to ensure complete condensation of the steam jet. Tests of an injector with different combining nozzles of varying length. can alone deteimine the best nozzle for any service. . The rate of decrease in the diameter of the combining nozzle towards its exit end is in most injectors uniform; that is, tlie difference between the diameters at any two equidistant sections is the same, the nozzle thus being ot conical form. In some cases, however, tlie rate of decrease is more rapid at first, as the condensation of the steam will be more rapid when it first meets the feed water. Thus