Trimix Fills and Helium Analysers

Paul Brookes

Hi

I recently completed my Mod2 so can now start seeing some cost benefits of owning a rebreather in terms of Helium fills.
My query is about analysing trimix fills at the filling station. I have yet to buy an He analyser and having spend an horendous amount of money on additional equipment and training to get my trimix ticket, it will be a while before I do.
Therefore, I expected my lds to have the facilities to verify the contents of a fill they provide. However, when I got my diluent and stage cylinders filled recently, they advised me that they do not have an He analyser as most of the trimix divers have their own. So I had to take it on faith that the he content was correct.

As it happens, my dive was at the NDAC in Chepstow and they let me use their analyser, but I wasn't impressed that I was expected to undertake a 50m dive on the assumption that the blender got their sums right.

If I was performing my own blending, then I would buy my own analyser, but surely if a shop is supplying the fill, they should be able to analyse it.

Is this right? Am I expecting too much here?

Thanks, Ramble over.
Paul

Beanie

Yeah you would hope wouldn't you, but then you can analyse trimix with an O2 analyser. Like we used to before the trimix analysers came out.

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lizardland

Yeah, it's amazing that we survived this long without a trimix analyser. Whatever have we been doing for the last ten years...

Did the people who told you that most divers have their own happen to be selling them as well? They usually say they same to new nitrox divers as well. It's 15 years since I did my nitrox cert and I still don't own an analyser.

My local shop has a helium analyser. I must admit I don't feel any more reassured with my gas checked with it as I do with just an analyser.

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nigelh

I took a trimix analyser on my mod 2 course.
When the shop served up 20/18 instead of 20/30 ordered for a 60m dive I was glad I had it.

They aren't in business now.

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nigelh

Doppler

Paul:

You are not expecting too much at all. Before He analysers were generally available, we had to take the helium content of our mix fills pretty much on faith, but that was then...

Some divers may be comfortable working out the suspected He fraction from the oxygen content, but most like to know... more or less... the ratio of helium in their mix based on a reading from an analyser and your shop really should think about making the investment.

Do they have a mix instructor on staff? If so, they must have an analyser kicking around someplace...

Mark Chase

On the other hand,We dived out of Weymouth and analised a 21/35 fill which we found to be air. I had a 14/65 fill which was 13.5/44 from a diferent source.

Maby you survived without an analisor but another way of looking at it is ignorance is bliss.

With Analisors now available for £250 -300 I think there is no excuse for a dive shop not to have one APART from if they are trying to make a few quid on short helium fills.

No shop ever said to me they dont have a Nitrox analisor because most of us have our own.

ATB

Mark Chase

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TordoffR

I believe that if the shop is selling you the mix, they should have an analyzer. That gives them their redundancy to check their work. One, the calculations of the mix and two, the verification from the analyzer. That being said, where is your redundancy? That's why I purchased my own analyzer. It really is a very inexpensive peace of mind, when it comes right down to it.

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Nemo1957

If a shop is turning a profit from doing mix fills they should be properly equiped to do so. I would find another dealer to give my money to.

bletso

Actually there are no stats for how many mixes are off enough to cause serious problems.

I agree, any dive using a mix someone else blended is a trust me dive. You are relying on someone else to mix what you will be breathing. If you payed him for the service, he/she will have a duty to perform. A contract of sorts, and they will be responsible to take any reasonable and prudent steps to assure they are selling you what they say they are.

If I mix my own, I have no one to blame but myself.

Any operator, from a legal perspective, who is mixing and selling a trimix blend should have an analyzer available. The technology is more advanced than it was ten years ago, and it is fast becoming a standard of the community.

Though you, the user, is ultimately responsible for the mix, I would not want to have mixed something in todays environment without someway to quantify and verify what I sold you.

For years we analyzed the O2 and that was sufficient. The technology supported it. Now that He analyzers are fairly common, it would be hard to justify not having one. (If in the mixing/sale of mixes)

There is nothing really wrong in not analyzing the He, when in mixing it yourself, your O2 percentage works out in the final mix. Afterall, the O2 percentage is much more critical than a couple percentage points on the He.

Dale

Nick uk.

I don't have my own He analizer, but i do have one for O2. I might be prepared to wing it as far as the He went, but deffinately want to know the O2% before making any dives over 50m

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