170 APPLICATION OF STANDARDIZATION AND GRAPHICAL 



In examining the diagrams it is of course impossible for anyone not familiar 

 with the designs whereon same are based to decide at a glance whether these dia- 

 grams will give proportions that are reasonable. For this purpose the writer has 

 prepared Plates 65, 66 and 67, which boilers were designed from data taken direct 

 from the diagrams given. These designs do not present any unusual features, and 

 in preparing them no difficulty was experienced in obtaining the proportions which 

 the charts predicted. 



The arrangement of tubes was kept as simple as possible in order to avoid un- 

 necessary complication of the smoke boxes since the few additional tubes that might 

 have been added would only be of doubtful value anyway. 



The diagrams may be used very readily for making a table of standard boil- 

 ers, and it is to be hoped that the data as given may prove of some benefit to the de- 

 signer who has not at his disposal a number of designs which have proven to be 

 successful. 



For the designer who has already a great number of designs available it may 

 follow that the methods outlined in this paper may be of benefit in coordinating his 

 various dimensions of boilers. 



The following example of the use of the diagrams may possibly demonstrate 

 their value somewhat more clearly: — 



Let us suppose that it is desired to design a boiler having the following char- 

 acteristics : — 



Type. Separate combustion chamber. 



Heating surface 2,200 square feet. 



TT C 



Grate surface =— ^ — ' 66.3 square feet. 



34 

 Area through tubes not less than 1,800 square inches. 



Grates not longer than 6' 3" 



Draft Natural. 



Since the length of grate bar is fixed, the grate area will be the determining 

 feature as to the diameter of the boiler. 



By reference to Plate 60 it will be seen that bars 6 feet 3 inches long will give 

 a grate surface of 67.5 square feet in the case of a boiler 15 feet diameter, i. e., 

 the diameter of furnaces appropriate to this diameter of boiler is such as to give 

 this amount of grate surface. 



The same diagram also shows that if this boiler is made 1 1 feet long we will 

 have 2,220 square feet of heating surface and an area through the tubes of 1,890 

 square inches. 



The diameter of the furnace can next be obtained from Plate 57 and is found 

 to be 3 feet 1 1 inches outside, while the depth of combustion chamber would be 33 

 inches. 



Plate 58 gives the number of tubes as 320. 



