Trimix

From GAWDAwiki

Trimix is a gas mixture made up of nitrogen, oxygen and helium^{Brubakk and Neuman}. Breathing air contains 78% nitrogen, 21% oxygen, and 1% trace gases, with argon being the highest portion. Trimixes are used in scuba diving, more commonly with commercial diving and experienced recreational divers. Although the gas mixes can contain any ratio of the component gases, several "standards" have been developed. These include helium and oxygen percentages of 21/35, 18/45 and 15/55. . Early studies found that the increased oxygen had no significant reduction of the effect of decompression sickness (ie the bends)^[1]. Divers using trimix utilize a helium descrambler to counteract the effect of helium on the vocal cords and to allow proper communications^[2].

Read More on Trimix Use: http://archive.rubicon-foundation.org/dspace/bitstream/123456789/4655/1/SI_2006_5.pdf

1. http://www.environics.com/Product/Gas-Blending-Gas-Delivery-Systems/
2. Brubakk, A. O.; T. S. Neuman (2003). Bennett and Elliott's physiology and medicine of diving, 5th Rev ed.. United States: Saunders Ltd.. pp. 800.
3. Logan, JA (1961). "An evaluation of the equivalent air depth theory". United States Navy Experimental Diving Unit Technical Report NEDU-RR-01-61.
4. Gernhardt, ML (2006). "Biomedical and Operational Considerations for Surface-Supplied Mixed-Gas Diving to 300 FSW.". In: Lang, MA and Smith, NE (eds). Proceedings of Advanced Scientific Diving Workshop (Washington, DC).