1 6 Loss of Heat from Covered Steam Pipes 



an experiment the value of C we were then in a position to com- 

 pute by Peclet's theory, the loss of heat from any sized steam pipe 

 under any pressure of steam, with any reasonable thickness of 

 the given covering, and with any usual temperature of external 

 air. 



L,et us now examine the figures of the table. 



Considering the large scale on which Mr. Barms' tests were 

 made, the number of tests taken to give an average figure, and 

 the care with which the tests were made, we are justified in hold- 

 ing that the theory is amply proven for different sized pipes, and 

 different thicknesses of coverings under the same steam pressure, 

 by the Barrus tests on "Asbesto- Sponge Felted," "Magnesia" 

 and "Asbestos Navy Brand." That the theory takes care of 

 any difference of steam pressure is proven first of all by Barrus' 

 and Jacobus' " Magnesia " and "Asbesto-Sponge Felted," sec- 

 ondly by Brill's, 130 Ibs'. and Norton's " Magnesia," by Jacobus' 

 and Brill's " Fire Felt," and by Brill 'sand 130 Ibs'. " Manville." 



Each of these examples are additional proof that different 

 pipe sizes antl different thicknesses of coverings are perfectly 

 taken care of by the theory. 



The only discrepancy that I think worth noticing is that be- 

 tween Barms' and Jacobus' "Asbestos Navy Brand." 



There is quite a difference between the values of C for 

 "Magnesia" tested in 1895 and in 1901. I think it is fair to 

 assume that the material has been improved in that time. 



The discrepancy in the case of ' ' Hair Felt ' ' has already 

 been explained. Prof. Jacobus' figure is no doubt the correct 

 one. 



Pipe coverings are not absolutely homogeneous, and experi- 

 ments of any kind are seldom in perfect agreement. Taken 

 altogether the experimental proof is very strong. 



APPLICATIONS OF THE THEORY. 



Effect of Thickness and Conductivity. Figure 6 shows clearly 

 the very great saving of heat that is obtained by even very mod- 

 erate thicknesses of coverings. It also shows how quickly the 

 economical limit of thickness of a covering is reached. 



In regard to conductivity, we see that halving this for a cov- 

 ering one inch thick, a usual thickness for this size of pipe, 



