Bought two new steel 80s...filled with air

[Catito]

So, bought two from Diver’s Direct (brand new). Even though their ad says “nitrox ready” DD says I need to go get them cleaned before nitrox goes in. A local reputable dive shop says—no need to clean for nitrox if nitrox fill is below 40%. I am going to use the tanks today (air). Can I fill them immediately with 32% or do they need to be cleaned?

Thanks in advance for your opinion.

 

[halocline]

Yes you can fill them with nitrox IF the source is from a bank or a blender, which is very likely these days. If the shop filling them is using partial pressure, then the tanks must be O2 clean because the partial pressure fill method introduces 100% O2 to the tanks.

 

[boulderjohn]

I once had snow tires installed on my car. A couple days later one of the wheels came off while I was driving. The lug nuts had obviously not been properly tightened. When I went back to the shop, they showed me a clause on about the 3rd page of the paperwork I had signed that said I agreed to inspect the lug nuts immediately after the work was done and upon going 100 miles. Thus, the fault for the wheel coming off was mine, not theirs.

I once bought a child's swing set that made a big deal advertising that it was fully guaranteed against rust for 5 years. When I read the fine print, it said that if any sign of rust appeared, I was required to sand it away and repaint that spot. Thus, if the swing set were to rust, it would be my fault, not theirs.

Thermo valves have a statement saying that they cannot be used for gas mixes greater than 40% O2. Many deco divers have Thermo valves on deco bottles holding 50-100% O2. If anything happens to them as a result of using those valves with those mixes, it is their fault, not Thermo's.

Many businesses have CYA policies. DD sold you a nitrox ready tank and then told you to clean it before using it with nitrox. If you do not clean it and something goes wrong, it is your fault, not theirs.

Is this a CYA policy you can ignore? I am not going to tell you what to think. That way, if something goes wrong, it will be your fault, not mine.

 

[UCFKnightDiver]

As halocline said, if the nitrox they're putting in your tanks is banked or continuously blended, you're good to get fills with any tank and it doesn't need to be O2 cleaned. If they're using the partial pressure fill method where they first put pure O2 into your tanks and then top off with air to get the desired nitrox mix, you might have an issue and need to get them O2 cleaned. If they're new tanks though, the risk is pretty darn minimal and the valves likely already have O2 compatible orings. The question then would be will the dive shop fill them...

 

[boulderjohn]

We have here a problem with scuba shop practices conflicting with other practices. What people have said about putting 40% or less nitrox into a non-O2 cleaned tank is indeed a scuba custom. On the other hand, the Compressed Gas Association (CGA) says any tank getting mixes above 23.5% must be O2 cleaned.

EDIT: An earlier typo said 13.5%

 

[UCFKnightDiver]

We have here a problem with scuba shop practices conflicting with other practices. What people have said about putting 40% or less nitrox into a non-O2 cleaned tank is indeed a scuba custom. On the other hand, the Compressed Gas Association (CGA) says any tank getting mixes above 13.5% must be O2 cleaned.

So if what you state is true, and the regulations state any tank getting a mix above 13.5% needs to be O2 cleaned, then every scuba tank filled, including with air needs to be O2 cleaned... I guess you could make an argument for hypoxic mixes...

 

[Catito]

I once had snow tires installed on my car. A couple days later one of the wheels came off while I was driving. The lug nuts had obviously not been properly tightened. When I went back to the shop, they showed me a clause on about the 3rd page of the paperwork I had signed that said I agreed to inspect the lug nuts immediately after the work was done and upon going 100 miles. Thus, the fault for the wheel coming off was mine, not theirs.

I once bought a child's swing set that made a big deal advertising that it was fully guaranteed against rust for 5 years. When I read the fine print, it said that if any sign of rust appeared, I was required to sand it away and repaint that spot. This, if the swing set were to rust, it would be my fault, not theirs.

Thermo valves have a statement saying that they cannot be used for gas mixes greater than 40% O2. Many deco divers have Thermo valves on deco bottles holding 50-100% O2. If anything happens to them as a result of using those valves with those mixes, it is their fault, not Thermo's.

Many businesses have CYA policies. DD sold you a nitrox ready tank and then told you to clean it before using it with nitrox. If you do not clean it and something goes wrong, it is your fault, not theirs.

Is this a CYA policy you can ignore? I am not going to tell you what to think. That way, if something goes wrong, it will be your fault, not mine.

Thank you. I agree that if you took a swing set diving and it rusted...it would be your fault.

 

[boulderjohn]

So if what you state is true, and the regulations state any tank getting a mix above 13.5% needs to be O2 cleaned, then every scuba tank filled, including with air needs to be O2 cleaned... I guess you could make an argument for hypoxic mixes...

It was a typo--I meant 23.5%.

 

[markmud]

Yes you can fill them with nitrox IF the source is from a bank or a blender, which is very likely these days. If the shop filling them is using partial pressure, then the tanks must be O2 clean because the partial pressure fill method introduces 100% O2 to the tanks.

Hi Halocline,

Please excuse my pedant post; hopefully, people think of my post as being informative and not . Being a jerk (or scientist) is not my intent.

There is a third method that does not require O² clean tanks, and that is nitrox generated by a Nuvair Nitrox membrane filter system. This system is used almost universally on SoCal long range dive boats. DV Conception had one.

This system filters out nitrogen from ambient air.

Of course, Boulderjohn's posts notwithstanding! He does have a point!

Nitrox Membrane Systems | Nuvair

thanks,
m²V2

 

[Scared Silly]

We have here a problem with scuba shop practices conflicting with other practices. What people have said about putting 40% or less nitrox into a non-O2 cleaned tank is indeed a scuba custom. On the other hand, the Compressed Gas Association (CGA) says any tank getting mixes above 23.5% must be O2 cleaned.

Agreed here. The compressed gas industry standard as set by CGA is that any cylinder with an O2 content above 23.5% must be O2 cleaned.

Some in the scuba industry have created their own "practice" that does not follow CGA standard. This practice is to fill any cylinder with up to 40% on demand nitrox from continuous blending or membrane systems. Both of which can be filled directly into a cylinder or banked (often called pre-mixed). The exception being nitrox mixed via by partial pressure blending directly into the cylinder.