120 SCIENCE OF SUCCESSFUL THRESHING 



surface of the tube-sheets. This has been incorrectly 

 called "sweating," but is really condensation. 



Temperature of Water and Steam in a Boiler. Al- 

 though water boils in an open vessel at 212 degrees Fah- 

 renheit, if it be confined, a pressure will be developed, 

 which will prevent it from boilmg until a higher tempera- 

 ture is reached. A certain relation exists between the 

 pressure and temperature of the steam in a boiler and for 

 any given pressure there is a corresponding temperature. 

 This holds true only for what is called "saturated steam," 

 that is, steam that is not heated after it is taken away from 

 the water where it was generated. Water in a boiler and 

 under the same pressure as the steam has practically the 

 same temperature as the steam. 



TEMPERATURES CORRESPONDING TO STEAM PRESSURES. 



lbs.= 212.0 degrees F. 



25 lbs. = 266.6 degrees F. 



50 lbs. = 297.5 degrees F. 



75 lbs. = 319.8 degrees F. 

 100 lbs. = 337.6 degrees F. 

 125 lbs. = 352.6 degrees F. 

 150 lbs. = 365.6 degrees F. 

 175 lbs. = 377.2 degrees F. 

 200 lbs. = 387.6 degrees F. 





