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.

THE STEAM NOZZLE. 21 The followmg table gives the approximate theoretical velocity of dry saturated steam into the atmosphere and into a vacuum of 28 in. mercury. It will be noted that the velocity does not increase at anything like the rate of in- crease of the pressures. When 150 Ibs. pressure is reached, the rate of velocity increase is very slovv. The great value of the vacuum will be noted, and also the high -velocity of even exhaust steam into a vacuum: — Table II. Pressure of steam. Pounds per square inch absolute. Velocity in feet per second into atmosphere. Velocity in feet per second into vacuum of 28 in. mercury. 10 2677 15 2900 30 1602 3263 50 2108 3510 75 2425 3671 100 2645 3804 125 2777 3905 150 2900 3983 175 3000 4050 200 3075 4100 250 3207 4190 WEIGHT FLOW OF STEAM. The weight of steam discharged in unit time is propoi'- tional to the area of the orifice through which it is dis- charging and to the velocity of discharge, and inversely proportional to the volume of unit weight of the steam at the orifice. That is, W = x * V., * The dryness fraction of the steam is here neglected. For greater accuracy, for i>„ should be substituted. x„ v., + (1 - x2) er where <r = speciflc volume of 1 Ib. of water.