What Is Trimix?
Trimix is a type of gas mixture that may be breathed while scuba diving. It is composed of helium, nitrogen and oxygen. The helium that is used in trimix diving helps to keep the diver safe when they are on a deep dive.
Trimix is commonly used during commercial diving and technical diving, when divers need to reach lower depths than is usual during regular scuba diving.
Different proportions of helium can be used while trimix diving. A Trimix 10 50 or 10/50 mix has 10 percent of oxygen and 50 percent of helium in the mix, with the remainder being made up from nitrogen.
Nitrogen is the most common gas in the Earth’s atmosphere. Oxygen is also common in the air, and it is essential for life. Without sufficient oxygen, the diver would die. Both nitrogen and oxygen can cause problems for a deep sea diver, however. While the diver is underwater, nitrogen passes into their bloodstream. As they return to the surface, this nitrogen can form bubbles in the bloods, which cause decompression sickness. This can be very dangerous and may even be fatal. Oxygen can also be harmful. Divers who are exposed to enough oxygen when they are at a substantial depth are at risk of oxygen toxicity.
Adding helium to the gas that is being breathed while diving can help to reduce the potential harmful effects of both nitrogen and oxygen, by reducing their concentrations in the breathing gas. Since less nitrogen is in the mixture, less of this gas enters the blood during the dive. This reduces the chances of bubbles forming during the return to the surface and of the diver becoming sick. The lower proportion of oxygen in the mixture is also important since it will reduce the chances of the diver being exposed to toxic levels of oxygen, which is particularly likely to happen when they are on a very deep dive.
Both nitrogen and oxygen can be more harmful to the diver when they are diving to greater depths. Using the trimix blend allows divers to reach depths that would otherwise be unsafe and unattainable. Trimix allows divers to explore parts of the ocean that may never have been seen before, and to which very few divers will be able to follow them.
Special training is required in order to be able to use trimix air safely. PADI, the Professional Association of Diving Instructors, runs a specialist Tec Trimix Diver course, for example. In order to begin training for trimix diving, divers must already have experience using enriched air and as a technical diver.