nitrox/air

[vicmac]

probably a daft question:blush: but can you use a tank for air that has previously been used for nitrox?

 

[fire_diver]

Yes. If you will be partial pressure blending the nitrox in the future, you need to make sure the air is "oxygen clean" air.

 

[sardiverdan]

Yes you can switch them back and forth as long as you do not go over 40% EANX. The issue will arise if you have the tank O2 cleaned for percentages above 40% EANX. You can still take a cylinder with 80% EANX in it, empty it out, and fill it with air. The only problem is you should not refill that same cylinder again with more than a 40% EANX fill. I would not worry too much about this because those of us who use high percentages of O2 (50-100%) will most likely have dedicated cylinders for that purpose only. We have no dive shops out here that blend EANX on partial pressure and I would assume your shop has it banked or they use continuous blending.

 

[fire_diver]

SAR, that's not entirely true. Many shops that blend nitrox already use O2 cleaned air. That air is fine to put into a nitrox tank without worrying about contamination. The only time you should worry about the air is if the shop is "air only."

 

[pnw_diver]

We have no dive shops out here that blend EANX on partial pressure and I would assume your shop has it banked or they use continuous blending.

I wouldn't make that assumption - my LDS does do partial pressure fills only, no banked nitrox, and no continuous blending.

 

[pnw_diver]

SAR, that's not entirely true. Many shops that blend nitrox already use O2 cleaned air. That air is fine to put into a nitrox tank without worrying about contamination. The only time you should worry about the air is if the shop is "air only."

As is the case most times, the answer is "maybe".

My advice to anyone that owns their own tanks and uses nitrox and air - ask (at least) two questions: Are your air fills O2 safe? How are your nitrox fills done? (banked, continuous blend, partial pressure blend).

It's practically a guarantee that any shop that's filling nitrox will have O2-safe air. It's a crapshoot with shops that are air-only. Ask, and if you're the least bit uneasy about the quality of the answer, get your fills elsewhere.

I don't know if this is typical, but my LDS keeps info on fill stations in the "local" area (within a four+ hour drive) and will call ahead for me to make sure I can get O2-clean fills.