O2 clean tank question

[Water Monkey]

It’s true that your cylinders are only as clean as your last fill.

But I believe that it is the responsibility of the operator of the fill station to insure that there is not a problem when filling your cylinders, regardless of what you bring in.

You could fill a cylinder half full of oil then dump 100% O2 on top of it and as long as the O2 was added slow enough it would be no problem. But if you add heat to that equation you had better be in the next county having lunch when it gets filled.

When I first started teaching Nitrox in the mid nineties the industry standard was that for anything over 21 % everything had to be O2 cleaned including your regulators. But they have backed off from that. I believe that it was more about income than safety. If using 100% O2 was that dangerous every welding shop in the country would have been blown to pieces by now.

All that said the incident rate for PP blending with 100% O2 is quite low.

 

[Dr Wu]

There is nothing wrong with that approach. Or more correctly, getting the proper mix may just mean ending the dive with the proper psi needed to top with air to get the desired mix or draining or filling the tank to the proper pressure before topping with air.

For example, let's say my last dive today was on 32% and I want to do a deeper dive tomorrow with 25%. With a gas blending app (on a palm, laptop etc) I know that if I start with 1200 psi of 32% and top with air I will get the 25% I want, leaving me ready to go tomorrow with nothing more to do than verify the gas with an analyzer.

Agreed and that is certainly valid.

But it's not what smellzlikefish was advocating.

I was simply pointing out that as a new Nitrox diver it is a good idea to plan the dive and obtain the proper mix accordingly. Not to assume you will get something close to 32% by topping off a tank of 36% with air.

 

[adm3745]

(There are no shops locally that have banked nitrox).

Thanks for any input.

Sea Level Scuba in Melbourne does Blended fills. He's got a really nice Nuvair system. He doesn't bank, but can offer you any custon EAN mix you want. All of my fills have always been accurate to .1% O2 and he can get pretty close with helium too. He blends up to %36 I think. It may be 40 without pp but I forget. His shop is 2 min off of exit 183. Prob around a 35 -40 min drive for you. Nitrox cards for $70-$85 depending on which tanks you have.

I see your diving HP 100 and 120. He can get those cold filled to 3500 as well. I know JND scuba pushes HP tanks on its customers so he must be able to get to 3500 too.

 

[Thezeker]

Man....thanks guys. There was a ton of killer information in response. Not only was the crux of my question addresses..i.e. the liability portion but I got some tech stuff too. I am a cpa by trade and have worked in litigation support so my thinking tends to go off in that direction now and again.

Again thanks so much for the input. FWIW for those wondering I do have my own analyzer and I do plan my dives.

 

[cbrich]

If all else fails, get another tank and dedicated it for air, or have plenty of tanks so you don't have to take it somewhere else to get it filled.

 

[rigdiver]

Take an O2 tech/Life Support Service and blending class. Few hundred bucks. And as stated get Oxyhackers book.
Then buy your own compressor and don't depend on anyone else. Now, it's as much as you want to spend or save?
Bill

 

[elan]

In short ...... O2 over 40% becomes a potential dangerous gas to work with. O2 is a very flammable gas and under pressure it can and will ignite when in contact with contaminants .

O2 is not flammable gas and it does not ignite O2 does not burn nor it bursts. O2 is an oxidizer other materials burn and burst in presence of O2


As to OP you are primarily interested in having the tanks O2 clean. Even if nothing happens at the station when you fill contaminated tanks with O2 it's possible that at the moment of pressurization some contaminates will burn and you will get the combustion products into your tank which you will be breathing yourself later and they will be bad for your health.

 

[elan]

Remember that if you have O2 clean equipment and you use air on it the equipment is no longer O2 clean!!!!!

While some certification agencies want you to believe so it does not stand any logic test. If you follow your logic then the tank is not clean right after the first fill done using partial pressure method as besides putting the oxygen you top it up with air

 

[adm3745]

haha exactly.

I also love the guys who say that nitrox from blended systems isn't O2 clean either. I heard someone say that he uses 2 filters on his system so it's O2 clean, but the other guy who blends nitrox doesn't put out O2 clean gas.

Just get some simple green and dilute it with water and you can do it yourself for practically nothing.

 

[ajduplessis]

ELAN: I am glad you undertsood what I was trying to say. I also learn some new things here daily.

Since O2 dont burn, I will have to use it the next time there is a fire that needs killing.