What does the fraction mean in regard to gas mixes?

[SparkySFD]

I think I know the answer to this but would like to ask. Im not certified to the Tech level.....YET. My goal is to someday soon get Tech 1 certified. The adventure of deeper wreck diving really apeals to me. I saw this chart posted on another thread and have copied it here:

Bottom Mixes
Depth in FSW Mix
10' - 80' EAN32
80' - 110' 30/30
110'-150' 21/35
160'-200' 18/45
210'-250' 15/55
250'-400' 10/70

Deco Mixes
Depth in FSW Mix
20' 100%
70' 50%
120' 35/25
190' 21/35

I believe these are GUE standard mixes. What do the fractions mean? Is the first number the oxygen content? Is the second number helium?

Obviously not all these numbers equal 100 percent. In the case of 250'-400' it lists a mix of 10/70 this would equal 80 percent, right? Is the last 10 percent of gas nitrogen, making this trimix?

Lastly where does heliox come into play?

 

[Laser]

You got it. First number is 02 and the second helium. The remaining is nitrogen ( trimix ) Heliox would not have any nitrogen.

 

[SparkySFD]

Thanks

I assume a mix of 20/80 would then be heliox?

Does GUE have standard mixes for heliox?

 

[oatmeal769]

was going to offer a bit of levity, but best not to bother.

 

[MikeFerrara]

Thanks

I assume a mix of 20/80 would then be heliox?

Does GUE have standard mixes for heliox?

The FO2/Fhe designation for trimix isn't unique to GUE. Every (well almost) one uses it.

GUE/DIR doesn't to my knowledge use heliox.

Standard mixes and the way they're untilized is one of the slickest aspects of how they do things, IMO.

It goes a long way in simplifying dive planning and calculating decompression.

 

[DepartureDiver]

Bottom Mixes
Depth in FSW Mix
10' - 80' EAN32
80' - 110' 30/30
110'-150' 21/35
160'-200' 18/45
210'-250' 15/55
250'-400' 10/70

Deco Mixes
Depth in FSW Mix
20' 100%
70' 50%
120' 35/25
190' 21/35


I believe these are GUE standard mixes.

Yes, those are standard GUE mixes.