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GUE Instructor
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Discussion Starter · #1 ·
was getting a bit stressed about the tech1 evaluation becuase my mix twinset is in need of O2 clean and i don't have a mix in them yet, with only a couple of days to go.

Out went a call through the shared consciousness, and up pops Clare with "Oh don't worry I have a spare set of 21/35 I can bring with me."

Fabulous. Problem sorted, stress gone.

nice one Clare.
 

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Irish Cave Diver in the making
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3,241 Posts
Why are you suprised , Clare has probably got a set of every gas mix you could conceive of.:angel:
Ahh, but that is her "spare set of 21/35" she has at least a couple of each standard mix :D
 

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GUE Instructor
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Discussion Starter · #6 ·
He'll breath more than that - I guarantee it.

Not that he will see much of the dive for his money though ;)
I have a suspicion you may be correct. However, our plan is for all three of us to look even more incompetent than usual first thing in the morning, so that he can't pick a strongest diver to go blind. We've been training hard to look incompetent for months, I'm sure you've noticed a slow downward spiralling of our skillsets as we slowly sink down the plughole of tech 1 :)
 

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Irish Cave Diver in the making
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Numpty question: if you wanted 21/35, do you actually need an O2 clean set? :confused:
Yes, cause you still need to add O2
Though the mix is 21/35 and at first would appear to be air and helium, it isn't.

Lets say you make 100 bar of the mix...

Add 35 bar helium, which leaves 65 bar for the rest. If you just added air, that is 21% O2, but you are have 65% of your total mix being the air, so the O2 content is 21% of the 65% - see?

Or, 35bar He plus 65bar air = 65% He / 13.65% O2 / 51.35% N2

You want 21% of the total mix, not just 21% of the air you add. So, you need to add pure O2 along with the He and air to get the mix.

So, to get 100bar of 21/35 you would actually need:

35 bar He
9.3 bar O2
Top with air to 100 bar (55.7 bar)
.
 
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Numpty question: if you wanted 21/35, do you actually need an O2 clean set? :confused:

(Good luck with the re-eval :))
Without doing any maths I'd say yes. If you add air to helium you would get a hypoxic mix. You need additional O2 to keep the FO2 up.

Cheers/Nic
 

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Guru
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She actually breathes 21/35 through a constant flow mask when hanging upside down from her heated rafter in the lead lined crypt back at her DIR secret underground lair you know. Heaven forbid that she would actually have to breath tyre gas for her 45 minute "Power Hang" each night :D
 

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She actually breathes 21/35 through a constant flow mask when hanging upside down from her heated rafter in the lead lined crypt back at her DIR secret underground lair you know. Heaven forbid that she would actually have to breath tyre gas for her 45 minute "Power Hang" each night :D
One day Howard - the Mistress will catch up with you, drop your trousers and paddle your bottom young man.
 

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Team Tricky: Diving with Twins
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One day Howard - the Mistress will catch up with you, drop your trousers and paddle your bottom young man.
I believe he's waiting with thinly veiled anticipation for this...
 

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Team Tricky: Diving with Twins
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