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.

18 THE STEAM INJECTOIi. the steam before expansion and at the exhaust pressure respectively. The value of x2 in the above formulæ having been obtained by means of a calorimeter, the value of x2 is given by the following formula : — + , - •_. = —1-------...........................(vii.) T, where ri\ and T2 = initial and final absolute temperatures, deg. Fah. ; Lj and L2 = initial and final latent heats of steam ; = drynesa fract ion of steam before expansion ; ! and 2 = entropy of water at initial and final temperatures. Aijplication of Formula, (v.).—To find the velocity of discharge of dry saturated steam issuing into the atmo- sphere from a boiler under an absolute pressure of 200 Ibs. per square inch, we first prooeecl to find the value of x2 by formula (vii.); xr is unity, as the steam is dry.* 966 673 — -86 approximately. From formula (vi.) we get V = 7 64-4 x 77o (3817 + o44‘6 - 212 - ;86 x 966) = 3033 fr. per second. If we consider the pressure volume diagram, fig. 14, in which the area Px Vx represents the work performed during the admission of unit weight (volume V,) of steam at pres- sure P15 and P3 V2 the work represented by th& steam (at * The effect of initial wetness of the steam is to reduce the velocity of discharge.