io Loss of Heat from Covered Steam Pipes 



The above coefficients by which we have modified K and A' 1 

 are taken from Figures i , 2 and 3 for a difference of 50 degrees, 

 and an air temperature of 65 degrees. 



Then 96. 2 = 1. 15 X 1.7 (/' 64.6) and/'=ii7. 117 64.6 = 

 52.4, which is so near 50 that we may take the value of 1.6 for 

 Q as final. 



We now know the temperatures of the inside and outside of 

 the covering. Transposing our fundamental equation for the 

 conduction of heat through a cylindrical covering, (Eq. i) we 

 get 



c= M'XN 



2 TT X difference of temps. 



The temperature of the inside of the covering we know to 

 be that of the steam, 365.2 F. ; the temperature of the outer 

 surface we have found to be 117; the difference is therefore 

 248.2. 



96.2 X .61 



C= 6.28X 248.2 XI2== - 453 



All the tests have been analyzed in this way and the value 

 of C determined. 



BARRUS' TESTS. 



These tests are on a far larger scale than any previously 

 made. Every precaution was taken to secure accuracy. The 

 final results have not yet been published, but a preliminary 

 description was published in Power of December, 1901, and the 

 average of the maxima and minima condensations there given 

 are used here. 



Through the kindness of Mr. Barrus, I am able to say that 

 those of these figures used here stand practically correct and the 

 temperatures, thickness of coverings and areas of pipe surface 

 have been given me by him for this paper. 



The steam pressure was 150 pounds. 



The pipes to which the covering were applied were 2 -inch 

 about 100 feet long, and lo-inch about 35 feet long. 



The length of each test was about nine hours, but the tests 

 were repeated day after day for a number of days, and the figures 

 given are the average. 



The tests were made in 1901. 



