Decompression (diving)

When decompression is called when diving the controlled reduction of pressure on the prevention of decompression sickness. The decompression is based on empirical tables ( decompression ) or by using dive computers that are based on a decompression model. This dive time, depth, and other factors determine the accumulation of inert gas ( mainly nitrogen ) in the body and thus the decompression required. The decompression is usually done in stages ( decompression ) decreasing depth and different durations.

Decompression

Decompression time (short Deco period ) is the period of time that is at least required to bring an organism without injury from a high to a lower pressure level.

Theoretically begins while scuba diving decompression after the point of greatest depth reached during the dive and will only be ascended. In practice, the deco time is divided so that there are decompression stops in decreasing depth and usually increasing length. The depths and lengths of the individual stops depend on the profile of the executed dive, the breathing gas used and the ambient conditions. The sum of the duration of all the necessary stops and the time for the change from one depth level to the next level add up to the total decompression time, which should be at least maintained in order to avoid decompression sickness or the bends.

While modern dive computers perform their calculations in real time and are already aware of a slow emergence, is diving after decompression table only the greatest depth reached and bottom time is important. In general, therefore, the decompression after diving computer is shorter than in the table.

Decompression

The decompression (short deco stop) is an intentional linger in a certain water depth during decompression. In this case, the bound in the tissue gas is slowly exhaled by the reduced pressure in lower water depth, so then can be turned up to the next deco stop or to the surface safely. Too quickly rise form in body tissues and in body fluids gas bubbles, which can cause the fatal decompression sickness ( " the bends ").

Simplistically, can the blistering compare the appearance by opening a bottle of carbonated mineral water: the pressure can escape very slowly (slow emergence / deco stop ) then it drips very little. Tear to the bottle but abruptly ( fast emerging ) to large gas bubbles and the water form bubbles out of the bottle.

Practical Implementation

In the simple scuba diving is immersed within the zero time, so that up to a safety stop no decompression stops are necessary ( eg 3 minutes at 5 m depth). However, this may have a maximum depth of 40 m should not be exceeded. Including stops are usually graded to 12 m, 9 m, made ​​6 m and 3 m. The duration of such stops depends on the used respiratory gases, the dive depth and dive time ( base time = duration of the dive to the start of the ascent phase ) from.

Interestingly, the practice of these stops continuously changes, since they only partially based on medical studies. As so often play physical models and phenomena discovered by chance a significant role.