Mance: Quarry Industry of Southern Indiana 77 



The accompanying drawing, submitted by the Harrison 

 Safety Boiler Works of Philadelphia, Pa., illustrates the Cochrane 

 feed-water heater. The firm is one of the oldest in the business, 

 and the Cochranes in use in this district are giving complete 

 satisfaction. 



The economical transfer of steam from the boiler to the engine 

 or pump that is to use it is often accompanied by a very material 

 loss, in fact, a greater loss than the ordinary observer would 

 suspect. Where steam leaves the boiler as simple saturated 

 steam, the amount of condensation in an unprotected steam line 

 represents a high percentage of the steam generated, and also 

 causes trouble on account of the large amount of water in the 

 lines. A series of tests made by Professor C. L. Norton of the 

 Massachusetts Institute of Technology shows that the yearly 

 cost of maintaining 100 square feet of piping at a gauge pressure of 

 100 pounds per square inch is for bare pipes $225 while the cost 

 for insulated pipes at the same cost of fuel would be from $25 to 

 $35.90. These figures are based on the price of coal in Boston, 

 but the percentage would be the same for any point. With 

 superheated steam the line losses are reduced to a minimum, but 

 since superheated steam would necessitate new engines, its use 

 at present appears to be out of the question. This point could 

 be looked into with profit by any owner who may be considering 

 the project of installing new machinery, or who may be planning 

 a larger power plant. For anyone about to erect a power plant 

 no better work on pipe covering can be found than Paulding's 

 Steam in Covered and Bare Pipes. All steam containers 

 should be covered, since careful insulation will eliminate from 

 80 to 90 per cent of the heat loss per annum. This loss can be 

 figured as three British thermal units per square foot per hour 

 per degree of difference in temperature between the uncovered 

 pipe and its surroundings. The actual loss depends upon the 

 diameter of the pipe, its position (whether horizontal or vertical), 

 the nature of the surface, and the velocity of the surrounding 

 air currents. Professor Gebhardt, in Steam Power Plant En- 

 gineering (pp. 550-553), gives the following example to show the 

 method of calculating the loss of heat in an unprotected pipe, 

 as compared with the loss in the same pipe when it is insulated: 



Required the saving per annum due to covering a pipe 10 inches in 

 diameter and 100 feet long; steam pressure 150 pounds, average temperature 

 of the air 76 degrees Fahrenheit; cost of covering applied 65 cents per running 

 foot; efficiency of the covering 85 per cent; cost of coal $2.50 per ton; plant 

 to operate 14 hours per day and 300 days per year. 



