Diving Operations

Diving Operations. For work underwater, apparatus of two kinds are used: individual diving suits and collective apparatus - diving bells and caissons. In some cases, mainly in tropical seas, small diving operations are carried out without the use of apparatus (e.g., cleaning the underwater parts of ships by natives who dive and remain underwater for about two minutes; the same method is still used today by pearl shell and sponge gatherers). Physicians and hygienists are mainly interested in work in apparatus, which is mostly carried out at increased atmospheric pressure. The modern diving bell is a strong steel box without a bottom, equipped with additional weights for submersion underwater, with benches for accommodating people, with telephone wiring, and with an incompressible tube through which air is pumped under pressure slightly exceeding the water pressure at the bottom. In caissons, communication with the outside air occurs through a series of locks with gradually changing pressure. Renewal of air in these apparatus is difficult. Work in them is carried out at depths not exceeding 40 m. There are also apparatus in the form of a closed steel vessel, equipped with thick glass and connected to the outside air by two strong tubes serving for the supply and extraction of air, which in this case has a pressure slightly exceeding atmospheric pressure; work in such apparatus can only be done by mechanisms controlled from the inside, having, for example, the appearance of movable pincers and serving for grasping objects and for carrying out simple work. Diving apparatus for one person comes in two types: those communicating with the outside air and those isolated from it. In the first case, the apparatus can receive air at significantly increased pressure. Ordinary diving apparatus - Rouquere-Denerez, Siebe and Gorman - consist of a rubber suit covering the entire body of the diver, except for the head and sometimes the hands, of a metal helmet tightly attached to the upper part of the suit ("shirt"), of heavy lead weights worn by the diver on the torso and feet, and of a pump supplying air inside the diver's suit. Excess air is released through a special valve. Often the apparatus is equipped with a reservoir with a certain reserve of air. The diver is connected to the diving boat from which the descent is made by a signal rope and a telephone. Apparatus of Butane, Dräger, Halley, Rice, etc., which isolate the diver, instead of being connected to an air-supplying pump, are equipped with devices attached to the diver's torso containing O₂ or air or oxilite and removing CO₂ and moisture. Such apparatus allow staying underwater for 2-4 hours, usually at shallow depths. Sometimes instead of a complete suit, such apparatus consist of a half-mask and a reservoir for air and weights. Apparatus in which the air is also under pressure close to atmospheric, but allowing work at depths up to 200 meters or more, are heavy steel casings resembling heavy knight's armor, with movable limbs on spherical joints and movable hooks at the ends of the hand casings; the joints are watertight; the upper half of the apparatus is lowered onto the diver who has entered the lower half of the apparatus and is screwed to it. In the head part of the apparatus, glass is inserted, there is a source of electric light, a telephone, and a supply of air or oxilite. There are lightweight diving apparatus (Kataoka), consisting of a half-mask tightly fitting to the face and covering the nose, through which air supplied from above under pressure is inhaled; through the mouth the diver exhales and with the teeth regulates the valve changing the stream of incoming air for breathing; breathing occurs no more than 5 times per minute; the diver remains at a depth of up to 80 m for 10-15 minutes and can be quickly and safely raised. In the USSR, diving was nationalized by a decree of the SNK of June 19, 1919, and concentrated in the NKPS. Diving operations are dangerous to health, since the diver during their performance is submerged in water and is subjected to increased pressure, increasing by 1 atmosphere for every 10 m of depth. At the same time, the diver breathes compressed air, subject to Henry's and Dalton's laws, but since the volume of air inhaled with each breath does not change, with each breath the diver receives correspondingly increased amounts of the components of air, of which in this case N (abundantly soluble in blood and in the body's fats at increased partial pressure) and O₂ have the greatest significance. Damage or breakdown of any part of the diving apparatus threatens mortal danger. The diver must possess considerable physical strength, good health, composure, resourcefulness and courage, must know well the design of the diving apparatus and the rules of signaling, and must be confident in the proper condition of the apparatus. For the protection of labor of divers, special rules are established, defining the necessary conditions of physical development and health status of persons admitted to diving operations: divers cannot be younger than 20 and older than 40 or 45 years, must have healthy heart, blood vessels, central nervous system, ears, and must not be obese. Descent is allowed only if the diver is in healthy condition and feels well; after eating, at least 2 hours must pass; after consuming alcoholic beverages - at least 6 hours. The bladder and, if possible, the intestines must be emptied. The diver's body is protected from cold by woolen underwear and a woolen cap; the latter also serves for wiping the fogging glass of the porthole. Dressing and undressing of the diver in cold weather must take place in a warm enclosed room. Before putting on the diving suit, the diver must make sure that his apparatus is in proper working order. Work is usually carried out at depths up to 45 m, but in individual cases it may be allowed at greater depths, up to 80 m, but exclusively for willing and previously prepared for deep-sea descents divers. During descents, a physician must be present; during work at shallow depths, he may be replaced by a medical assistant. At the place of work there must be: a set of necessary medicines, dressing materials, a supply of O₂, and during work at greater depths - a recompression chamber or recompression bag. Descent must be made at a speed of no more than 4 m per minute; ascent is done slowly, with stops of increasing duration as the surface of the water is approached; the stops last longer the longer the stay at depth, since the release of gaseous N accumulated in the body occurs slowly, but with a rapid decrease in atmospheric pressure, the abundant bubbles of N appearing in the blood cause blockage of blood vessels with serious consequences (see Gas embolism). The duration of permissible continuous stay underwater depends on the depth of immersion and is established by special rules. The total duration of a diver's stay underwater should not exceed 4 hours per day. Rules for labor protection during diving operations in the USSR were approved by the People's Commissariat of Labor of the USSR on January 16, 1924, under No. 31/314.