Compressed Air Work And Diving 1909

STAGE DECOMPRESSION. 3 direction of the Aclmiralty Committee, and has been adopted for use in the British Navy. Note. — I hroughout this book pressures are +, or by gauge, unless otherwise stated. Choice of the orker.—All clivers and caisson workers who have to work at a greater pressure than 18 Ibs- shoulcl undergo a strict medical examination before bcing admitted to work, and this examination shoulcl be periodically repeated. All men suffering from chronic disease, alcoholic excess, ear troubles, &c., shoulcl be excluded, as well as men who are at all fat or who have ever had any serious symptoms after a reasonably slow decompression, since Such an occurrence points strongly towards excessive SLisceptibility to compressed air illness. For high pres- sures the skinniest men available shoulcl be selected. Compression.—T he rate of compression shoulcl be SO regulated as not to cause any discomfort or pain in the ears owing to incomplete opening of the Eustachian tubes. A too rapid descent, or compression, might cause mechanical injury followed by middle ear inflammation. In the Royal Navy clivers can descend to 30 fathoms two or three minutes, and when the exposure is to be dt great depths, the descent shoulcl be as rapid as possible • ii order to limit the time of Virtual exposure. In the case of tunnel and caisson workers it is recom- mended that the compression shoulcl be rather slower than with clivers. This is because the diver has the rate of compression under his own control, whereas with caisson workers several men are in the air-lock together and amongst them may be one or two who find a little difficulty in inflating their Eustachian tubes quickly. A rate ol 5 Ibs. in one minute for the first 15 Ibs., and 10 Ibs. C1y minute afterwards, will be quite slow enough under