SUPERHEATED STEAM 



SATURATED steam, or water vapor, is steam at the lowest temperature 

 at which it can exist as a vapor under a given pressure. Dry saturated 

 steam not in contact with the water from which it has been formed may 

 have its temperature increased above that corresponding to its existing pressure. 

 Steam whose temperature is higher than the temperature of saturated steam at 

 a given pressure is said to be superheated, the difference in its temperature and 

 that of saturated steam at the same pressure being the degree of superheat. 

 Superheating requires isolation from the liquid and saturated steam cannot be 

 superheated while in contact with water if the water is maintained at the same 

 temperature as the steam. 



Superheated steam can and does often exist in the presence of water, but 

 when such is the case the temperature of the water is lower than that of the 

 superheated steam. 



Superheated steam cannot condense until its temperature has been reduced 

 to the temperature of saturated steam under the pressure at which it exists. 

 Just so long as its temperature is above that of saturated steam at a corresponding 

 pressure it is superheated, and before condensation can take place that amount 

 of superheat must first be lost through radiation or other means. 



