with such fittings and European engineers are leaning toward the use of 

 steel for this work. 



FLUCTUATION OF SUPERHEAT A given amount of superheating surface 

 installed in a given boiler will give varying amounts of superheat for different 

 furnace arrangements, for different fuels, and for different capacities at which 

 the boiler may be operated. Due to this obvious fact, it is essential that in the 

 designing of a superheater for a particular installation all of these factors be 

 given proper consideration to assure the furnishing of the right amount of 

 surface to secure the desired results. 



Further, a definite arrangement of superheater, boiler and furnace will give 

 varying amounts of superheat under varying conditions of fire, load and operation, 

 this being necessarily true of a superheater swept by the main body of the 

 products of combustion. While this is a fact that should be appreciated by 

 the prospective user of superheated steam, with a properly designed super- 

 heater the variation in superheat will not be excessive and momentary fluctuations, 

 with proper operation, may be reduced to a negligible amount. 



As a matter-of-fact, the point to be guarded against in the use of superheated 

 steam is that a maximum should not be exceeded. While there may be slight 

 momentary fluctuations in the temperature of steam delivered from individual 

 superheaters, where there are a number of boilers on a line the temperature of 

 the combined flow of steam in the main will be found to be practically a constant, 

 resulting from the offsetting of various furnace conditions of one boiler by another. 



When a superheater installation is contemplated in a plant already in 

 operation, the builders of the steam motors there in use must be consulted as to 

 the ability of their product to satisfactorily operate with superheated steam. 

 In the case of new steam motors, manufacturers should specify the maximum 

 amount of superheat with which their apparatus should be operated. 



With high degrees of superheat, say, over 250 degrees, apparatus of a 

 special nature may be necessary and it is questionable whether the additional 

 cost, care and liability to operating difficulties will be offset by any fuel saving 

 accomplished. It is well established, however, that with the degree of superheat 

 to which this article is limited, 100 to 200 degrees, operating difficulties have 

 been entirely overcome. 



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