what is trimix?

[Cave Diver]

IndigoBlue once bubbled...
When you mix helium with EAN36 do you still call it trimix?

Or does it then go by heli-trox?

I know you still mark the tanks with XX/XX/XX for O2/He/N2.

But I don't know what you call it then.

Triox is a gas with over 21% Oxygen content that also contains Helium. Commonly used in shallower dives (100'<) and the most common example is 30/30 (30% O2/30% He, 40% Nitrogen)

Trimix normally refers to gasses that have O2 content of less than 21%. A good example is 18/45

Heliox is a combination of Oxygen and Helium. Heliox is normally only used very deep when it's necessary to get rid of all trace amounts of Nitrogen.

 

[Don Burke]

IndigoBlue once bubbled... When you mix helium with EAN36 do you still call it trimix?

Or does it then go by heli-trox?

It's still trimix. Mixing EAN and helium to make trimix is pretty efficient if you have a membrane system to make EAN. I think helium and EAN32 makes for better gasses.

IndigoBlue once bubbled... I know you still mark the tanks with XX/XX/XX for O2/He/N2.

Tanks are normally marked XX/XX for O2/He. It is assumed the rest is N2.

 

[MikeFerrara]

Mixing he with eanx makes mixing easier and you know exactly what you have without an he analyzer because the eanx is a known quantity. You only need analyze the O2.

For instance the GUE mixes are set up such that they can all me mixed by topping with ean32. If you put in 35% he and top with 32% you get 21/35. If you start with 45% He and top with 32% you get 18/45. It's the same with 15/55 and 10/70.

Of course you overshoot the He a little.

If you look at the math used to decide how much of each gas is needed to get a certain mix you'll see why they did it this way. It's the same reason some guys like heli-air only you get better mixes.

If you spend some time mixing you'll really appreciate it.