The Value of Trimix

diving photoIf you think that scuba diving is all about attaching

an oxygen tank in your back and breathing through it

with the use of a regulator, then you are wrong.

There’s a lot more to scuba diving than that. In fact,

pure oxygen is never used in scuba diving, especially

on deep sea diving.

In recreational diving, air is commonly used and not

pure oxygen as most people assume. Air is basically

composed of 70 percent nitrogen and 30 percent oxygen.

However, nitrox mixes are now being used a lot more in

recreational diving as it decreases the chances of

nitrogen sickness.

Although nitrox is still composed of nitrogen and

oxygen, the oxygen concentration is a lot higher than

air. This will reduce the risk of nitrogen sickness or

bends, but it trades off depth. The more oxygen there

is in your scuba diving tank, the shallower you are

allowed to dive.

So, just why is pure oxygen not used in deep sea

diving? This is because of oxygen toxicity. As you go

deeper underwater, the pressure increases and oxygen

toxicity becomes a factor. So, by reducing oxygen in

the air you breathe, you will be able to go deeper.

However, by doing so, you will also increase the

amount of nitrogen in the air you are breathing which

can result in nitrogen narcosis when you go deeper as

well as nitrogen sickness or the bends.

You may wonder how deep sea divers go deep underwater.

The answer to this question is trimix. Trimix is a

special air mix designed for deep sea diving. Trimix

is composed of oxygen, nitrogen and helium hence the

term trimix.

Helium is used because it reduces the proportions of

nitrogen and oxygen. This means that because the

oxygen is reduced, it will enable the diver to dive

deeper. And, because nitrogen is reduced, the diver

will not experience nitrogen sickness or nitrogen


The great thing about helium is that it can be

breathable under pressure and it has very little

narcotic effect. Because of helium’s low density, it

reduces breathing resistance at depth or at pressure.

Also, helium does not enter slow tissues as readily as

nitrogen, which causes the bends.

The only disadvantage of helium is that it conducts

heat 5 times faster. Also, during descent, deep sea

divers suffer from a condition called hyperbaric


If you become a deep sea diver, you will learn about

the different variations of trimix. Some will be named

trimix 10/70 and etc. If you come across with trimix

10/70, it will mean that the gas inside the scuba

diving tank will be composed of 10 percent oxygen, 70

percent helium and 20 percent nitrogen. This kind of

mix is suitable for dives up to a hundred meters or

330 feet.diving photo

These are the things that you have to remember about

trimix. As you can see, deep sea diving is not as

simple as it may seem. There are so many aspects in

deep sea diving that you have to be aware of and one

of them is the gas used for breathing.

So, before you don your scuba diving gears and you

plan on going very deep, keep in mind that deep sea

diving is a specialty course that one needs to take

before they undertake dives like this. Deep sea diving

is different from recreational diving. It takes years

of training and a lot of discipline.

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