QUALITY OF STEAM. 1 19 



" The formula for calculating the percentage of moisture 

 when the throttling-calorimeter is used is the following: 



H- h- k(T-f) 



w 100 X 7 , 



in which w = percentage of moisture in the steam, H= total 

 heat and L = latent heat per pound of steam at the pressure in 

 the steam-pipe, h = total heat per pound of steam at the pres- 

 sure in the discharge side of the calorimeter, k = specific heat 

 of superheated steam, T= temperature of the throttled and 

 superheated steam in the calorimeter, and / = temperature 

 due to the pressure in the discharge side of the calorimeter, = 

 212 Fahr. at atmospheric pressure. Taking = 0.48 and 

 t = 212, the formula reduces to 



H ' 1146.6 o.48(r 212)* 



CORRECTIONS FOR QUALITY OF STEAM. f 



i 



Given the percentage of moisture or number of degrees of 

 superheating, it is desirable to develop formulae showing what 

 we have termed " the factor of correction for quality of steam," 

 or the factor by which the ' * apparent evaporation," determined 

 by a boiler-test, is to be multiplied to obtain the <l evaporation 

 corrected for quality of steam." It has been customary to call 

 the proportional weight of steam in a mixture of steam and 

 water "the quality of the steam," and it is not desirable to 

 change this designation. The same term applies when the 

 steam is superheated by employing the "equivalent evapora- 

 tion," or that obtained by adding to the actual evaporation the 



* William Kent in the Report of the Committee on Boiler-tests, A. S. 

 M. E. , 1897. 



f C. E. Emery in the Report of Committee on Boiler-tests, A. S. M. E., 

 1897. 



