78 



Indiana University Studies 



The temperature of steam at 150 pounds pressure = 366 degrees Fahren- 

 heit. 



Difference of temperature between the steam and air = 366 — 76 = 290 

 degrees Fahrenheit. 



Loss per square foot per hour, bare pipe = 3 X 290 = 870 B.T.U. 



Loss per square foot per day, bare pipe = 870 X 14 = 12,180 B.T.U. 



Loss per square foot per year, bare pipe = 12,180 X 300 = 3,654,000 

 B.T.U. 



100 Hneal feet of 10-inch pipe has an external surface of 282 square feet. 

 Therefore the loss per year from the bare pipe is 282 X 3,654,000 = 

 1,030,000,000 B.T.U. (approx.) 



Assuming a net available heat of 10,000 B.T.U. per pound for the coal, 

 the equivalent coal consumption is 51.5 tons, valued at 51.5 X $2.50 = 

 $128.75. 



The covering will save 85 per cent of this, or $109.50 per annum. 

 The pipe covering applied will cost 100 X $0.65 equals $65. 

 In this ease the covering will pay for itself in considerably less than 

 a year. 



The figures can be changed to fit any case in the district, and 

 1 have figured the cost and saving by covering the pipe in at least 

 two of the mills and find that at the lower price of coal here, the 

 saving due to insulating pipes will pay the cost of such insulation 

 in about 16 months for the commonly used 6-inch pipe. 



Another thing to be avoided is short turns in piping, for 

 altho little is definitely known concerning the friction of steam in 

 pipes, it is known to have a great effect on the condensation of 

 steam passing thru the pipe, and it is therefore an economical 

 proposition to have feed pipes as nearly straight as possible. 

 Another practice is to give the pipes different colors according 

 to the kind of material carried. This practice is employed in a 

 large plant that I visited at Crawfordsville, Ind., and, in 

 addition to giving the power-house a neat appearance, it makes the 

 work of fitting easier. 



Coal and Firing. The cost of coal from the local coal fields 

 is so low that the choice of a coal worth considering in a discussion 

 of power generation in the Southern Indiana quarry district 

 is narrowed to the coal of the local fields. The better grades of 

 coal from the eastern fields cannot compete on account of the 

 high cost of transportation as compared to the short-haul freight 

 on local coal. Coal at the mines can be bought (1914) at from 

 90 cents to $1.35 per ton, according to the grade and size. The 

 kind of coal in use in most of the quarries is that furnished by an 

 Indiana company at $1.10 per ton for run-of-mine, and $1.35 

 to $1.45 for lump coals. The freight rate per ton for the coal 



