Practical Tunnelling

Practical Tunnelling

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1896 edition. Excerpt: ...compressed air and horse-power of the perforator.--First, for the percussion-cylinder. Taking an average length of stroke of 8 inches, with an area of piston of 7-068 square inches, the net volume of air consumed per stroke, supposing that the air was admitted for the whole of the stroke, was(7-068 x 8 = )56'544 cubic inches. Adding 10 percent, for the air that filled the clearance for each stroke, the total volume consumed per stroke was 62-2 cubic inches, and for 250 strokes per minute, single-acting, the consumption was (62-2 250 = )15,550 cubic inches, or 9 cubic feet per minute. Second, for the regulating cylinder, of which the area was 5-4556 square inches, and the stroke 2-834 inches, the net volume for one double stroke was 30-9224 cubic inches, supposing that the air had been admitted at full pressure for the whole of the stroke. Adding 5 per cent, for the volume of the clearance at each end of the cylinder, the total volume consumed for one double stroke, was 32-4685 cubic inches, and for 250 strokes per minute, 32-4685x250 = 8,117 cubic inches=4-7 cubic feet per minute. Taken together, the total consumption of compressed air per minute was as follows: --By the percussion-cylinder.... 9 cubic feet per minute. By the regulating-cylinder....47, Total 137 Or, say, 14 The amount of this estimate is in excess of that of Mr. Sopwith's estimate, which was 12-662 cubic feet per minute. But, applying the ratio of 1 cubic foot of compressed air per minute supplied by 1 horse-power of the compressing machinery, it is proper to adopt the conclusion arrived at by Mr. Sopwith that 14 horse-power of compressing machinery was required for the supply of air of 6 atmospheres absolute pressure, to work one perforator. The nominal total pressure...
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Product details

  • Paperback | 180 pages
  • 189 x 246 x 10mm | 331g
  • English
  • Illustrations, black and white
  • 1236773632
  • 9781236773630