Stupid question - Gas mixtures

[diverjed]

Taking Helitrox course, NAUI. When they say my mix (to include Helium) will be 24/30, or 28/20, the 24 and 28 would represent the He mix? And the denominator value would be the nitro?

Which is which? Also, what tables exist for determining appropriate deco bottom times for Helium mixes?

 

[Spectre]

No. 24% Oxygen, 30% Helium. And 28% Oxygen, 20% helium.

 

[gkndivebum]

1st number is O2 percentage, 2nd number is He percentage.

Your instructor should go over this, as well as the deco dynamics of He in mixes. NAUI has tables,
as does IANTD>

 

[Doppler]

Convention dictates that Oxygen percentage is always first, helium second, nitrogen (when stated at all) is last.

Tables should be discussed in the class and demonstrated in practice.

 

[diverjed]

Thanks