Bulletin . he efficiency of the fan and canvas pipe. In one drift ventilated bycanvas tubing the end of the tubing was 50 feet from the breast andthe air stream was so directed that the current hit the back within afew feet, was deflected to the floor, and turned outward about 20 feetfrom the breast; a mucker at the breast was shoveling dry material ina smoky, stagnant atmosphere, and complaining of headache and 92 UNDERGROUND VENTILATION AT BUTTE. nausea; the cause of the mans discomfort was removed readily bylowering the end of the canvas pipe a trifle and by directing the airtoward the brea
Bulletin . he efficiency of the fan and canvas pipe. In one drift ventilated bycanvas tubing the end of the tubing was 50 feet from the breast andthe air stream was so directed that the current hit the back within afew feet, was deflected to the floor, and turned outward about 20 feetfrom the breast; a mucker at the breast was shoveling dry material ina smoky, stagnant atmosphere, and complaining of headache and 92 UNDERGROUND VENTILATION AT BUTTE. nausea; the cause of the mans discomfort was removed readily bylowering the end of the canvas pipe a trifle and by directing the airtoward the breast. Failure to keep the end of the ventilating pipe close enough to thebreast also results in inefficient ventilation. Figures 39 and 40show air rapidly loses velocity in traveling 60 feet to the breast,having practically no velocity at the breast though leaving the endof the pipe at 5,000 linear feet per minute. On the other hand, Figures13 and 14 show that with the end of the canvas pipe only 20 feet from. Fig. .*8.—Effect of transmitting air by canvas pipe to a hot working place: a, 3,, downcast shaft, 61° F. wet bulb, 61|° F. dry bulb, 97 per cent humidity;6, No. 2J fan; c, 68° F. wet bulb, 71° F. dry bulb, 68 per cent humidity ; d, 10-inchcanvas pipe; e, drift;,/, 71° F. wet bulb, Tl\° F. dry bulb, 76 per cent humidity;g, 76° F. wet bulb, 77£° F. dry bulb, 96 per cent humidity, muck pile here; h, 81° bulb, 88° F. dry bulb, 91 per cent humidity, 12-inch hole in back gave rock tem-perature of 91 per cent humidity. the face of a drift, the velocity at the face was well over 300 feet perminute, though the issuing velocity at the end of the pipe was onlya trifle over 4,000 feet per minute. Where canvas tubing is used inlevels, it can easily be kept within 50 feet of the face, as a 25 or 50foot length is easily removed before blasting, not over 5 or 10 minutesof one mans time being required. Figure 41 shows results of experiments with canvas-pipe
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectminesandmineralresou
