Compressed Air Work And Diving 1909

AIR SUPPLY. 5 least 5 cub. It. per man per minute, measured at the cxisting pressure, or 300 cub. ft. per man per hour. I his larger air supply is to allow for fumes gene- rated by blasting and other impurities; but if these niipurities are at all excessive, a larger air supply will be needed. Table I. For Diving.— 1 his table has been arranged with exposures sufficiently short to keep the time, which must be spent in decompression, within reasonable limits. As an example of its use we may take the case of a diver who is going to do some work at a depth of 96 ft. He would descend as rapidly as possible to the bottom, taking say two minutes in doing so. At the end of 55 ~ 2 = 53 minutes at the bottom, or fifty-five minutes from the surface, he would start coming up, and would do so quickly (the ears can always follow any rate of decompression), until he reached a depth of 30 ft., when he would stop three minutes. At the end of three minutes he would ascend to 20 ft., and stop there ten minutes, and at the end of the ten minutes he would ascend to a depth of 10 ft. and stop there fifteen minutes. He would then ascend the remainder of the way to the sur face. I he time taken in ascending to the first stopping place might be about two minutes, and a half minute or so for each 10 ft. of ascent between the stoppages and the last 10 ft. He should move his arms and legs during each stoppage in order to hasten desaturation. 1 he stoppages are regulated by signal from surface according to the readings of the pressure gauge. A diver has sometimes to descend twice or oftener at short intervals. When this happens the more slowly desaturating parts of his body will not have become de- saturated at the time the seconcl descent begins. To nicet the inereased risk the two periods at the bottom