How Decompression Chambers Work
A decompression chamber is a device used to prevent and treat decompression sickness (the bends), a disorder caused by a rapid decrease in the external pressure on the body. When a person is exposed to great external pressure, as in deep-sea diving or caisson work, additional nitrogen from the air enters his body tissues and fluids. Normally, most of the nitrogen a person inhales is exhaled without being absorbed by the body. However, as the external pressure increases, a larger amount of nitrogen is absorbed, and it is carried by the blood to the body tissues.
If a person returns to normal atmospheric pressure too rapidly, the nitrogen may come out of solution and form bubbles. These bubbles may then obstruct blood vessels or distort body tissues, causing pain and sometimes paralysis. The basic principle of a decompression chamber is to allow the pressure on the body to be reduced slowly enough so that the dissolved gas can escaj>e without forming bubbles.
A typical decompression chamber is a steel cylinder 5 to 6 feet (1.5-2 meters) in diameter and 8 to 10 feet (2-4 meters) in length. However, the chamber may be any size or shape so long as it is large enough to contain a person and can safely withstand the required internal gas pressure.
There are several different ways in which decompression chambers are used. In surface decompression, divers emerge rather quickly from the water, enter the chamber, and are then re-compressed with air to the pressure equivalent to that of their underwater environment. The pressure inside the chamber is then slowly reduced until it is the same as the pressure outside the chamber.
A submersible decompression chamber is one that is lowered into the water and filled with a pressurized gas that serves to keep the water out in the same way that water is kept out of a submerged inverted tumbler. After working, the divers return to the chamber, seal the hatch, and they are then hauled on deck where their decompression is completed. Once on deck, the chamber may be connected to a deck decompression chamber so that the divers may be transferred to larger, more comfortable quarters without any decrease in pressure.