Deep Sea Diving: The Importance Of Trimix

One of the most important aspects of scuba diving that a diver has to study is how to set up the breathing tank. Divers do not utilize oxygen in their tanks, they use (or, increasingly, used to use) compressed air. However air is approximately 70 percent nitrogen and 30 percent oxygen and the nitrogen can result in nitrogen sickness under pressure, so more and more divers are turning to Nitrox.

Nitrox is not air, but it is still composed solely of nitrogen and oxygen, although not in the same percentages, which you can change. The problem with increasing the amount of oxygen in the mix is that there is a greater likelihood of suffering from oxygen toxicity the deeper you go. Therefore, the trade off is that the more oxygen you use, the shallower you may swim.

It sounds like a rough decision, you can suffer from either nitrogen or oxygen toxicity, take your choice. However, there is a third option and it is known as Trimix. Trimix is the 'air' that deep sea divers use. It is a mixture of three gases, as its name suggests: nitrogen oxygen and helium.

Helium is used as a form of filler. It does not do us any injury and it does not do us any good either, but it allows divers to take a lung full and it reduces the volume of nitrogen and the volume of oxygen thus decreasing the likelihood of illness.

The only difficulty with helium is that it conducts heat five times faster oxygen and nitrogen. This leads some deep sea divers to suffer from a condition called hyperbaric arthralgia. Hyperbaric arthralgia is a kind of joint pain that some divers experience as they go deeper than 100 feet in salt water.

Deep sea divers have to learn about the various Trimixes as part of their curriculum, because one day they will be accountable for choosing the mix they use. The choice is not only compressed air, nitrox and Trimix, because there are different ratios of the gases in Trimix to take into the equation as well.

For instance, a 10/70 Trimix will be composed of 10 percent oxygen, 70 percent helium (and 20 percent nitrogen). This form of mix is suitable for diving to a depth of 330 feet in salt water or 100 msw (metres in salt water). Fresh water is a little lighter than salt water. This does not count at lower depths, but it does after a hundred feet.

Breathing and gases are only one aspect of diving that you will have to master if you want to go diving. Another aspect of diving that is linked with diving is the speed of ascent. Divers used to get taught not to come up faster than their smallest bubbles, which is around 60 feet per minute. However, lots of instructors now think that this is still too fast and recommend 30 feet per minute with a three minute wait at 15 feet.