234 



Average energy consumed by uncovered pipe, 2n.(!!> watts. 

 Average energy consumed by covered pipe, 07.88 watts. 



(211.69 — 97.88) -^ 211.(J9 = 53% the efficiency of the pipe cover- 

 ing. 

 211.09 watts = 0.283 horse-ixjwer 

 97.88 watts == 0.131 horse-power. 

 Difference —- 113.81 watts = 0.152 horse-power. 

 Area of radiating surface, 395.G4 sq. in. = 2.74 sq. ft. 

 113.81x10^^4.2x107 = 27.09 cal. per second loss. 



= 0.107 B. T. U. per second loss. 

 0.107x3600x24 = 9240 B. T. U. loss per 24 hours. 

 0.107 X 3600 X 24 X 365 = 337 xlO* B. T. U. loss per year. 

 337 X 10^ -^ 2.74 = 123 x 10* B. T. U. loss per sq. ft. per year. 

 "Problem ; Compute the saving for the first year for 1,000 feet of 

 three-inch pipe, assuming that the pipes are maintained at the tempera- 

 ture used in the above test, that coal develops 14,000 B. T. U. per pound 

 and costs .$0.00 per ton, and that the loss in the boiler, etc., is 50%. The 

 pipe covers cost 25 cents per squiire foot, and inttM'cst and depreciation 

 are 10%." 



Loss on 1,000 square feet of pipe per year 121] x 10' B. T. TT. 

 1 lb. coal gives up on combustion 14,000 B. T. T'. 

 1 ton of coal gives up on combustion 2Sx10" B. T. II. 



