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Divers’ decompression is a concept we hear about soon in our first diving lesson. It is always present in our minds when we practice our favorite sport, but we are rarely clear about what diver’s decompression is and what this really means.
The dives we do in recreational diving, within the safety limit, do not require a decompression stop beyond the recommended safety stop. This fact causes many people to refer to recreational diving as “no-decompression diving”. But no-decompression diving does not exist. The fact is that you cannot make a no-decompression dive. So, the question is this.
What Does Divers’ Decompression Consist Of?
Humans cannot breathe underwater unless they are supplied with air. Scuba divers carry compressed air in their tanks. The most common gas mixture is 79% nitrogen and 21% oxygen. Pure oxygen is very harmful, so we mix it with an inert gas such as nitrogen or helium in the case of Trimix. The toxicity limit of nitrogen is 40 meters, which is also the depth limit for recreational diving.
Inert gases do not interfere with physiological processes. However, as pressure increases, more nitrogen begins to dilute in the divers’ bodies like sugar in a cup of tea. When the ascent begins, the pressure decreases, and this dissolved gas must leave the body again through breathing. This happens on any dive, which is why we say that divers’ decompression happens always.
While it is true, in the diving that we practice within the safety limit, we ascend at the correct speed to get rid of the nitrogen without further complication. Recreational diving aims to prevent the body from absorbing so much gas that it cannot get rid of it fast enough during a direct ascent to the surface.
Otherwise, the dissolved nitrogen in our body would form microbubbles that could pass into the bloodstream or invade other tissues, causing decompression sickness.
The first symptoms are fatigue, malaise, headache, and loss of appetite, and if the size of the microbubbles is not reduced, these symptoms worsen.
Divers’ Decompression on Deep Dives?
During deep dives, divers’ decompression is determined by the amount of inert gas (nitrogen or helium) absorbed by the body, which is logically much greater. The deeper you go, the more atoms of gas you will absorb with each breath. This implies that to get rid of all this gas, we must give it time to leave our bodies. This is why tech divers make decompression stops during the ascent. During the stop, the gas is given time to leave the tissues, return to the lungs, and from there, to the exterior. At the end of the estimated deco stop time, the diver continues the ascent and repeats the process as many times as necessary. The dive computer calculates when and for how long, these stops should be made. These stops can also be planned with the help of dive tables.
To be totally honest, it should be noted that the mixes used by technical divers may be different for each section of a dive. This is because the air mixture commonly used in recreational diving would be inefficient, dangerous at the depths they reach, excessively heavy, and, besides, would imply eternal decompression stops.
For example, they use mixtures with a higher percentage of oxygen during decompression stops and thus accelerate the gas purging process. What is the percentage? That’s a secret only available to the most experienced divers. Do you want to be one of them? Take a look at this page PADI TECHNICAL & SIDEMOUNT COURSES
As we have seen, divers’ decompression is unavoidable and must be done following the proper procedures for each dive. By following these recommendations, you will be able to enjoy your dives without problems.