Trimix is a breathing gas which is composed of oxygen, nitrogen and helium. You use it when you dive at great depths, in order to prevent compressed air problems. Because with normal breathing gases, the partial pressure of oxygen and nitrogen is so important, that these can damage your body. Helium serves as filling gas thereby, so that the pressure of the other two gases is diminished. The advantage is that helium does not damage the body and reduces the risk of a rapture of the deep.
There is also an alternative, where nitrogen is completely replaced by helium. This gas is called heliox.
What must I keep in mind when using trimix?
Since the percentage of oxygen is lower than for the other two gases; you have to carry a larger quantity of breathing air with you.
For every phase of the dive, you need different ratios of gas mixtures, so that you get the optimal quantity of oxygen. Thereby there is TravelMix to descend, BottomMix for the stay in the depth as well as DecoMix for ascending and the decompression stops linked to it.
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