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.

PKINCIPLES OF THE INJECTOR. 80 Application o f Formula (xxviii.).—To calculate tlie ratio by weight of water to steam passing through an injector when the pressure of the steam entering the latter is 15 Ibs. per square inch absolute, tlie feed water temperatuie is 60 deg. Fah. and the delivery temperature 168 deg. Fah., 213 + 965 - 168 vv = ------------------------------------- 168 - 60 = 9-3Ö. That is, 9’35 Ibs. of water are mixed with each pound of steam passing through the injector. If in formula (xxviii.) the numerator and denominator be transposed, the ratio will then be that of tlie steam to the water. Tliat is: S = —ts ~ t2— .... (xxix.) . ti + Lj — (s where S = weight in pouncls of steam to 1 Ib. of water. If the quantity of feed water dnaiwn by tlie inije©tor from the feed tank in, say, an liour is known, tlien the quantity of steam uised by thø injector in au hour is given by multiplying tlie value of S in formula (xxix.) by tlie weight of feed water in pounds. That is: Qs = Q- . (xxx.) ti + M - t3 where Q, = quantity of steam in pounds per hour, and Qw = quantity of feed water in pounds per hour. Application of Form/ula (xxx.).—To calculate the amount of steam used by an exliaust injector per hour, tlie pressure of the »team entering' the injector’being 15 Ibs. pøi square inch absolute, the temperature of the feed water 68 deg. Fah., the delivery temperature 190 deg. Fah., and the quantity of feed water used per hour 22,800 Ibs. (2,280 gallons): _ 22800 (190 - 68) 213 + 965 - 190 = 2815 Ibs. approximately.