Aqualung

History

The man plunges since mists of time in Apnée but it was always limited by the duration and the depth. The problems to be solved are the following:

supply air (oxygen) with good pressure;
the rejection of toxic carbonic gas for the man;
the increase in the pressure of water with the depth which prevents the movements of inspiration (pressure with 10m of depth is the double of the atmospheric pressure);
mobility.

Léonard de Vinci (1452-1519), imagines a mask with pipe bringing the air to the plunger. Usable for depths not exceeding a few tens of centimetres this technique is unrealistic from 1 meter of depth, water already exerts there on the rib cage a pressure equivalent to a weight of 200 kg, breathing is thus very difficult there.

The bell of Edmund Halley (1690) (physicist and astronomer which discovered the cycle of the comet which bears its name) imprisons air which is regenerated by a contribution of barrels of air.

John Lethbridge (1715) imagines the armor of diving of which an opening is used for the air supply by bellows and the other with the evacuation of the foul air.

The word diving-suit , of the Greek skaphe (boat) and andros (man), is used for the first time in 1775 by the Abbé of the Vault in its work Treated theoretical and practical construction of the diving-suit or boat of the man. The diving-suit heavy feet of Augustus Siebe (1837) consists of a rigid helmet with port-holes, fed in air (with a pressure higher than the atmospheric pressure) by a pipe connected to a pump on the boat, of a flexible combination and ballasted shoes. There remains still nowadays used for certain work. One reaches depths from 60 to 90 m but it there of the accidents (section of the pipe, random air flow, drowning…) and a lack of autonomy. Displacements are slow what is due to the weight (90 kg on the whole) and to the driving position (maximum resistance of water to displacement). The flow of air is more or less regular and unsuited to the needs for the plunger.

See also: Diver

The aqualung

Inventor

It is the French Jacques-Yves Cousteau who in 1943, markets with Emile Gagnan the modern aqualung. It is of the improvement and the modernization of inventions of the 19th century (Rouquayrol and Denayrouze) and of the beginning of the 20th century (Yves the Prior). The patent Co-deposited by Cousteau for this invention will put it at the shelter of the need for the remainder for its life.

The development of the aqualung is related to several technological discoveries:

the invention of effective compressors and relatively light bottles of storage of the compressed air (starting from the physical laws on the pressure of the gases of Boyle and Mariotte (1660)) ;
the development of palms by the commander Louis de Corlieu in 1934 (already outlined by Léonard de Vinci);
the development of valves with pressure reducer for the engines of cars to gas by Emile Gagnan at the beginning of the Years 1940.

Cousteau and Gagnan meet and decide to apply the system of pressure reducer automatic to the bottles of air under pressure and create, in 1943, the first aqualung Aqualung . " the mistral" then " royal the mistral". Thereafter " the spiro 8" will be an invention of Cousteau and Gagnan, innovator by his system has two stages, ancestor of our modern pressure reducers.

The equipment

The autonomous diver is usually equipped:

of a clothing of thermo isolation;
of a mask which surrounds the eyes and the nose and which makes possible the clear vision in diving while making it possible to compensate for the variations of pressure (by pressure balancing of the air captured in the mask);
of palms for displacement;
of one or more bottles; one speaks about block of diving or mono , Bi or tri to specify the number of bottles; the block contains a gas mixture (Air, Nitrox or Trimix) under pressure between 170 and 300 bar) whose capacity with the atmospheric pressure can be 2,3,6,9,12,15,18 or 20 liters of mixture. These blocks is out of steel, sometimes reinforced by carbon, or out of aluminum;
of a pressure reducer, which makes it possible to breathe the gas mixture with the environmental pressure;
of a stab connected to the bottle via the direct system allowing him to vary its Buoyancy according to the depth and of its needs.
of a Pressure gauge, to supervise the pressure of the gas mixture in the block and to know the quantity of remaining gas;
of instruments of decompression, more the current being the Computer of diving, but some ones still use a diver's watch and a table of decompression;
of a Parachute of stage;
of a belt of ballast (if necessary).

Certain plungers use a Recycleur in which the expired air is treated to be respirable again without danger: the CO₂ is absorbed and the expired air is enriched out of oxygen. The air circulates thus in closed circuit or half-closed ( Semi-closed Rebreather , SCR). The first solution not releasing any bubble on the surface, it is used, inter alia, by the combat plungers (but it does not allow the major divings).

In a near future, it should be possible to see arriving of the diving-suits of diving using of the respiratory fluid with the place of mixtures Gaz them.

Use

The aqualung allows:

automatically to output the air according to the needs for the plunger and either continuously;
to provide the air to the good pressure is that corresponding to the depth of water, which makes it possible the plunger to inspire without effort;
to get rid easily of carbonic gas of expiry.

The stabilizing waistcoat ( stabilizing jacket in English, also shortened in “stab”) makes it possible to change buoyancy and to balance in water according to the Archimedes' principle. The stab can be inflated with the mouth or automatically with the direct system , which is connected to the bottle. The autonomy of diving and exploration varies 2 a.m. to 30 minutes following the depth (respectively 10 m and 60 m without taking account of the stages of decompression). Displacement is more flexible and fast thanks to the hydrodynamism. One swims in 3 dimensions with palms. However the problems inherent in the pressure remain, and visible breathing can frighten the animals.

See too

Internal bonds

Plunged underwater

External bonds

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