234 



Average energy Cdiisuiiied hy uncoviTed pipe, 211.00 w.ntts. 

 Average (iicrgy cniisiiiiii'd by cdvered iiipe, !>7.s,s watts. 



(211.(!!) — Ul.ss) -H 211. (■)'.> = .".;{% the elliciciicy of tlie pi]ie cover- 

 ing. 

 211.(;!) watts =: 0.2K3 horse-i>ower 

 1)7.88 watts = 0.131 horse-power. 

 DifiFerence =^ 118.S1 watts == O.I.VJ horsepower. 

 Area of radiating surface, :5!).'».(i4 stp in. — 2.74 s<|. ft. 

 113.81 X 10' H- 4.2 X 107 = 27.<)!> caj. per second loss. 



= 0.107 15. T. T'. per second htss. 

 0.107x3000x24 = 0240 I?. T. V. loss per 24 hours. 

 0.107 X 30<J0 X 24 X 305 = 337 xlO* B. T. U. loss per year, 

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

 "Problem: Compute the saving for the first year for ].(M)(» 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. T'. per pound 

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

 pipe covers cost 25 cents per s<piare foot, and interest and depreciation 

 are 10%." 



Loss on l.(MM( square feet of pijie per year 123 x 10' B. T. U. 

 1 lb. coal gives up on combustion 14,00f) B. T. T'. 

 1 Ion of coal gives ui) on coiiiluistion 2SxlO'' B. T. U. 



