Trimix question

[access]

I’m thinking of getting trained to dive trimix but am working out the costs involved in getting the mix.
I use a compressor that allows constant flow nitrox mixes up to 40%.
Would I be able to decant helium in to the cylinders and then top off with a nitrox mix?
And is it difficult to calculate what the nitrox mix should be?
Any help appreciated

[DecoWarrior]

well you could if you wanted a mix that used it of course you could top off with nitrox 21, depends what mix you want to end up with!, work it out off a blending program and crunch some numbers

[access]

Originally Posted by DecoWarrior

well you could if you wanted a mix that used it of course you could top off with nitrox 21, depends what mix you want to end up with!, work it out off a blending program and crunch some numbers

What would be a good program that would use nitrox % mix as opposed to oxygen/air partial pressure?
then I could try to workout the limitations of only being able to use nitrox 21 to 40 in the trimix.

[NotDeadYet]

The original home of the trimix course, Key West Diver in Florida (now sadly gone), blended their gas from mixing helium topped off with either premixed EAN32 or 36 from their massive nitrox banks. The DIR standard gases grew out of the techniques they developed there.

There are charts available on the internet which show how to mix various gases using helium and premixed nitrox. When I did my trimix course the mixing calculations were covered anyway, don't know if they still are.

[NotDeadYet]

Originally Posted by access

What would be a good program that would use nitrox % mix as opposed to oxygen/air partial pressure?
then I could try to workout the limitations of only being able to use nitrox 21 to 40 in the trimix.

If you know the partial pressure formula then you can work out what nitrox mix to use.

[Scuttler]

Why not do an Advanced Gas blending course with TDI.....you'll know the answer then

[access]

Thanks NotDeadYet
At this stage I’m just looking into the feasibility of mixing my own trimix
before deciding whether to do the course or not.
If I can work mixing with my current setup then the course could be worth doing
but if getting a fill results in a long trip to a filling station then I’ll forget it.
Have you any idea what the charts for the nitrox top off are called? so I can search the net.

[access]

Originally Posted by Scuttler

Why not do an Advanced Gas blending course with TDI.....you'll know the answer then

Could be a bit expensive to find out that I can't

[stevechesh]

have a look at the spreadsheets here: tools

[access]

Originally Posted by stevechesh

have a look at the spreadsheets here: tools

Many thanks, that should help