Regular air in Nitrox tank

[melfox26]

Is it ok to fill a Nitrox tank with regular air? I own two Nitrox tanks, but have the need sometimes, depth-wise or financially to dive on regular air. Is this common practice or a no-no? forgive my ignorance, but I'm new to the whole tank owning thing.

Mel

 

[Scott Riemer]

I actually had a similar but reverse question. Can you use a tank that has been used with air to dive nitrox later? Example situation: You've been diving air and decide to get nitrox certified. Do you need to buy a new tank or can you use the same one?

 

[scubaculture]

have the tank oxygen cleaned and it'll be fine

 

[melfox26]

You can go from an air tank to a Nitrox tank if you get the tank Nitrox/O2 cleaned, which an LDS can do for you. It'll range from around 50 bucks for a new alum tank, to around 125 for a used steel tank.

Mel

 

[MechDiver]

You can go from an air tank to a Nitrox tank if you get the tank Nitrox/O2 cleaned, which an LDS can do for you. It'll range from around 50 bucks for a new alum tank, to around 125 for a used steel tank.

Mel

I don't know why this has to be a constant discussion, mostly wrong.

There is no such thing as "nitrox clean". It's either O2 service or its not.

You ONLY need to O2 clean a tank if it will be partial pressure filled, or used for EAN above 40%. You CAN use a tank for air AND nitrox, AS LONG AS the air meets nitrox quality (Grade E Nitrox). But, different shops have different criteria, good or bad.

And, if you knew the answer (or thought you did), why did you ask it to begin with

MD

 

[Dan Gibson]

I hope you aren't actually paying that much for O2 clean service.

You can go from an air tank to a Nitrox tank if you get the tank Nitrox/O2 cleaned, which an LDS can do for you. It'll range from around 50 bucks for a new alum tank, to around 125 for a used steel tank.

Mel

 

[melfox26]

I hope you aren't actually paying that much for O2 clean service.

I was quoting direct from my LDS website in my reply above. It does seem a bit high, but what do I know.

Mel

 

[Atticus]

1. Those rates for O2 cleaning a tank are a little high. Well, a lot high in the case of the steel tank.

2. Like MechDiver said, but I'll ellaborate:

A tank is either cleaned for oxygen service or it's not. If your local shop does partial pressure blending in your tank to produce nitrox then the tank and valve need to be oxygen service. If they use a membrane system, PSA, etc. then the tank and valve do not need to be oxygen service *see below.

If a tank is oxygen service and you want it to remain that way then you should only put oxygen compatible air (or oxygen compatible nitrox) in it. Not all nitrox is oxygen compatible.

If the tank is not oxygen service then you can either put grade E (normal SCUBA) air in it or premix nitrox in it.

I use the slang terms "dirty air" or "dirty nitrox" to refer to grade E (normal SCUBA) air or nitrox that has not been run through a hyperfilter. The terms "oxygen compatible air", "clean air", or "clean nitrox" are how I refer to gas that has been run through a hyperfilter. These are my terms and are probably not recognized industry wide. To be clear, there is absolutely nothing wrong with breathing/diving "dirty nitrox" - I do it all the time. I just don't put it into my oxygen service tanks.


* You should talk to your local dive shop to determine how they do your fills, and to see if they have any special policies above and beyond the basic scuba industry rules. It's their call if they are comfortable filling your tank or not.


EDIT: In the paragraph about dirty gas that has not been run through a hyperfilter I do not mean to suggest that it is common practice to pump nitrox through a hyperfilter. I am referring instead to nitrox which is made with normal un-hyper-filtered air through a system such as a continuous flow mixing station. Some shops may hyperfilter nitrox but I have not personally seen this.

 

[Drew Sailbum]

Grade E air is the term for air which is not filtered to the higher level of purity. If Grade E air is placed in a cylinder that was in oxygen service, then the cylinder needs to be cleaned again prior to use in oxygen service.

Modified Grade E air is air which has been filtered to a higher level of purity. Modified Grade E air may be added to a cylinder without compromising its oxygen service status.

 

[sharpenu]

Nitrox is just (filtered) air with oxygen added. There isn't anything magical about it. Think of air as EANx21. Some shops charge extra for "Nitrox air",EANx21, hyperair or whatever they choose to call it. This "hyper-air" is simply standard grade e with a few less impurities (less oil, for example). I wont fill my tanks at any shop that does this. The extra filter doesnt cost that much extra to use, I feel like this is to milk the diver out of a few extra bucks. Besides, I feel like asking them why they have to charge extra for the "clean air".

BTW, O2 cleaning here runs you about $25 most places and includes a visual. Nitrox fills are around $5 to $7 and air runs about $1 to $3.