Rebreather diving is part of the Tek dive (see « What is Tek or Technical Diving ? »), It is the bubble-free side of the dive. You think that with a bottle of scuba diving you would enter the world of silence, and well the truth is that you must try a recycler to enter totally into this universe.
Very simply the recycler is in fact only a kind of big bag in which one blows on one side and one inspires of the other when one breathes. To compensate for our consumption of O2 and therefore to add in this bag not to be missed there is a small diving bottle filled with pure oxygen with an injection system connecting the whole. To remove the CO2 released in this bag, a reserve of soda lime is added to fix this gas in order to purify the mixture that is breathed. In order to counteract the effect of the pressure and re-inflate our bag when we go under water we connect another small bottle of dive filled with what is called the diluent (usually air but this May also be nitrox or trimix, see « Increase safety with mixtures : Trimix »). This gas also makes it possible to reduce the amount of oxygen if it was to be too high, which is why it is used in addition to an electronic measuring system in order to control during all its immersion what one breathes. Here you know in a few lines the principle of a diving recycler.
You will understand that the recycler is not as easy to use as a conventional scuba diving equipment. Its use requires a suitable training and a longer preparation time before getting into the water. The cost of purchase and maintenance is also a significant factor in the disadvantages of this equipment. But then why would you want to use such a system? There are many advantages to going to the recycler, first of all the silence of which we spoke. The disappearance of the bubbles makes it possible to no longer frighten the fauna; You can get closer to the fish and they no longer appear in the photos or in the middle of a video. It also cools less quickly thanks to the hot air circulating inside.
This air is hotter and moist than the one that comes out of a bottle (Joule expansion) because the reaction of CO2 with lime leads to an exothermic reaction (heat). The humidity of the exhaled air also persists, which lessens the lung mucous membranes and reduces the dehydration in the dive. By controlling the oxygen level constantly in the respiratory loop of the system, decompression is improved, which limits the risk of accidents. The recycler can also considerably increase its autonomy and therefore the time that can be spent under water. It also allows to spend less money when helium is used in large quantities during its dives.
