What do you think

JonnyB

Hi guys, picked up my dil today. And my analyzer decided to act up.
So, i am not 100% sure what i have, but according to the fill label,
i should either have 17/32 or a 17/35. Which would you put on your computer to be on the safe side?

/Jonny

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botle maker

If I have not analised it I do not dive it.

decoweenie

Assuming 17% O2 is correct, 3% difference in Helium means negligible difference in term of deco, IMHO.

There are bigger differences using difference GF values. Just remember that deco is not an exact science...

And you could use your Rebreather to determine the O2%, if needed.

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womble

By fill label, do you mean what you stuck on the tank to say what you wanted? Or is this what the dive shop has analysed it as??

If it is what you asked for, then there is no guarantee that what you asked for is whatyou have recieved. Dont dive it.

If it is what the shop have analysed the contents as, or at least the O2 percentage, then I would put 17/35 into my computer, the highest helium concentration, although 3% He difference is negligible.

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RichClark

That sort of variance in helium isn't going to make significant any difference to your deco schedule, but i would probably enter in 17/35.

Make sure you know the o2 of your dill though, if your analyser is screwed, you can always use your rebreather (the worlds most expensive analyser)

Cheers

Rich

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Outlaw

Jonny man

are you saying you dare to dive something without analysing yourself?

hmm, nice to know

Take care.

Spyros

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JonnyB

Let me clarify!
I always analyze what i get.
Today i was not the one picking up the tank from the store.
So when i got the tanks i asked my buddy if they analyzed it.
He told me yes, but they did not write down the percentages, they wrote down in bar what they filled.
Now this center is a big center, i will not name anyone, but they are famous for their strict ways... Anyway, i believe that they had a student fill my tanks, cause i know they are running a trimix blender course this weekend.
Why? Because i ordered 16/30 mix, and they labeled what they filled in bars, but they wrote 70 or 76 bars He (can't tell if it is a 0 or 6), 4bars of O2 and then they topped it with Air. So far no problem other that it does not add up to my 16/30 order. Anyway, they also wrote that they filled to 200bars, but when checking i had 220. So now we start to get different values and my He analyzer is not working and my buddy is picking me up before the store opens.
The O2 is correct, checked it with 3 different devices.
So you guys recommend me setting up a 17/35 mix on the computer do you?

/Jonny

__________________
A quote from Crazyduck - In remembering our own Rob Davies.
"Outbound flight 777 heavy you are cleared for flight
Due west into that warm red Texas sunset
You have angels on your wings and divers memories on your six."

Rest In Peace

http://www.divetekcyprus.com
http://www.diveccr.com

babar

Wouldn't you want to use the lower he % to calculate it as a higher PN2? Then you would have a built in safety factor for niterogen loading? Or am I way off base here?

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JS1scuba

it's trivial

Once you put it on your unit you will get an accurate O2 reading, that's the critical part. For purposes of conservatism set the helium at 35%.

When helium content is less than 50% +/- 5% is insignificant to the calculation of decompression. However it's always best to err on the "greater helium content"

The critical part of this mix is the oxygen content. If your CCR unit is calibrated properly you will see the oxygen content of the mix on start up.

Simple method of testing your helium is the "squeek test" take a few breaths and recite something -- if you sound like a munchkin for about 45 seconds you are on the high end of 40-50% helium -- if less than 30 seconds you are in the 35% and less helium ....... (really it works im not kidding ) (i can see grown men going to the garage now with a stopwatch reciting scenes from the )

Cheers

JDS

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Dave & Sandy

If the O2 is correct you can assume the He is ball park (+- 5%). Makes little difference to deco for the depth you'll be using it at.

Before using He analizers, on OC we would mix, analize O2, dive if O2 was Ok, re blend after dive on left over mix. Never a problem. You just had to dump after the first remix to be sure your He wasn't getting too far off course. You'd plan deco on +5% of what you'd be aiming for if you were worried.

At the end of the day do what you feel comfortable with.

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