Searching info about membrane nitrox-systems.

[Rune Øien]

Does anyone here have any experience with, or info about, different membrane systems?
Reliability, accuracy, service cost, limitations, downsides?

Rune.:rolleyes:

[Anders Bomholdt]

What I found:

http://www.coltrisub.it/CATALOGO_COMPRESSORI/STAZIONI_DI_RICARICA/HTM/NITROX/membrane_system.htm
This costs 107.000 Dkr. in DK.

Bauer has a model, that I haven't found a price tag on:
http://www.bauer-kompressoren.de/en/produkte/atemluft/nitrox/b-trox/details.php
As its Bauer, I bet its not cheap :)

When are you planning to have it installed and running? I have gotten addicted to the diving around Ålesund since being there in April :D

Anders

[rjack]

How much gas are you pumping? For your home or a dive shop?

Coltri makes some:
http://www.nuvair.com/shopsite_sc/store/html/nitrox_sport.shtml

A huge downside is just having 2 compressors.

Richard

[Rune Øien]

What I found:

http://www.coltrisub.it/CATALOGO_COMPRESSORI/STAZIONI_DI_RICARICA/HTM/NITROX/membrane_system.htm
This costs 107.000 Dkr. in DK.

Bauer has a model, that I haven't found a price tag on:
http://www.bauer-kompressoren.de/en/produkte/atemluft/nitrox/b-trox/details.php
As its Bauer, I bet its not cheap :)

When are you planning to have it installed and running? I have gotten addicted to the diving around Ålesund since being there in April :D

Anders

Hi Anders. If its the best solution for nitrox at our dive-club (AAsdk), I hope to have it installed for your next visit :) But I lack first and even second hand experience about the system. And I seldom trust the provider of the products to give the hole truth:rolleyes:

Rune.

[Rune Øien]

How much gas are you pumping? For your home or a dive shop?

Coltri makes some:
http://www.nuvair.com/shopsite_sc/store/html/nitrox_sport.shtml

A huge downside is just having 2 compressors.

Richard

Hi Richard.
I try to convince my fellow members in Ålesund diveclub to invest in a 32% system, and then i need to know whats the best solution for us. Today we use a Bauer 320, and a 6*80*300 storage. Nitrox by blending from a cascade.

Would we need a extra hp-compressor?
I hope, in time, to eliminate the use of normal air in our club

LP-compressor vrs. supply from existing storage?

End pressure? Is 232-300 bar possible? Why not ?

Rune.

[rjack]

Well, I don't have a membrane system but I know they are very finicky to changes in supply pressure to the membrane. So if you took air off your bank you'd need a good regulator to ensure proper flow to the membrane then run the compressor to output to your cylinders. ~2x pumping the same volume of gas. Not very efficient.

Typically people install large LP compressors to supply the membrane with just the right flow and pressure. This gas must be quite clean to keep the membrane from being fouled.

A membrane and LP compressor end up being quite expensive. You are already buying O2 cylinders, and it will take a lot of gas to make a membrane pay for itself. Especially since when continuous blending you can use 99% of the O2 supply tanks.

In my home system, I continuous blend 32% and then put that in my bank of cylinders 1x300cf, 2x415cf, 2x444cf. These largest tanks are 310bar although I usually don't pump that high to save wear and tear on the compressor.

So my recommendation in the short term is to clean the banks and pump 32% into them by continuous blending (change out your oil to a sythetic. add a CO and moisture analysis if you don't have these already). You'll need a mixing stick which is cheap, and simple to build.

Until everyone is properly trained on how to continuous blend, restrict the nitrox pumping to a couple people (so you don't blow up your compressor). Have everyone else fill their cylinders off the banked 32%.

Have any remaining air divers in the club pump their gas directly from the compressor instead of from the banks.

This is my home system. Not sure how much is applicable to your club:
http://new.photos.yahoo.com/rjack321/album/576460762329659376

Here is a very nice system set up by a now deceased friend:
http://pontificatingnobody.com/Denton-FillStation/

If you don't have Oxyhacker's handbook I recommend it:
http://www.airspeedpress.com/newoxyhacker.html

In the long term, you can investigate if a membrane could save you money. I doubt it, but maybe. You really need to be pumping alot of nitrox. O2 just isn't that expensive to buy vs. concentrating from the atmosphere. If you find that everyone really does switch to nitrox and you're pumping tens of thousands of liters a month, maybe a membrane would pay for itself. If that's the case, you've invested almost nothing to continous blend. An O2 regulator, $20US in parts to make a mixing stick, and another 02 analyzer ($100US if you make it yourself). Pretty cheap to get started.

And since you may have an issue with costs, keeping the cost down and getting everyone converted to nitrox is a good first step IMO.

I'm no compressor expert, but happy to help anyway I can.

Cheers,
Richard