Scuba Tanks & Nitrox

[Bogie]

Scuba Tanks and Nitrox

Recently I was denied a fill at 32% Nitrox on two of my brand new x7 steel 100 scuba tanks from a shop that only does partial blending. I was surprised since Worthington the manufacturer, states they are cleaned for oxygen. I had only filled with Nitrox 32% on all other fills. These were blended fills.
It would seem that if Worthington says they are clean and the shops that I bought them from used the correct lube on the Yoke they should be ok to do partial blending.
I guess this is not true and you have to pay a shop separately to do their own oxygen cleaning and put their label on the tank. Also if you get your tanks filled with just once with E grade air, they are no longer oxygen cleaned.

Two CGA grades explained:

The CGA Grade "E" quality verification level has become the specification most widely referenced for sport diving. CGA Grade "E" is generally considered to be the absolute minimum acceptable breathing gas quality for SCUBA diving, and many consider it to be too liberal. Filling an "Oxygen Clean" cylinder with CGA Grade "E" will introduce hydrocarbon contamination such that the cylinder is no longer considered O2 clean and may not be used for partial-pressure blending.


"Oxygen-Compatible" is CGA Grade "E" with reduced maximum acceptable carbon monoxide, hydrocarbon and particulate levels. The International Association of Nitrox Divers (IANTD) and American Nitrox Divers International (ANDI) created this designation for gases used in technical diving and gas blending. The U.S. Navy and the American Academy of Underwater Sciences (AAUS) have also issued "Oxygen-Compatible" specifications. All the "Oxygen-Compatible" specifications are similar but not identical. For the purposes of this discussion we'll use the IANTD "Oxygen-Compatible" specification.

Well, I was surprised at this finding. Now I guess to get partial blending I have to pay another $100+ to get my new tanks oxygen cleaned with new stickers. Some shops don’t even honor other shops stickers. The consumer is sort of stuck in the middle.

Does anyone else have problems with Nitrox fills, stickers, etc.?

Any comments?

 

[rstofer]

When the tank manufacturer says their tanks are Nitrox compatible, you need to read the fine print. They are talking about preblended Nitrox <= 40%. The tanks are NOT O2 cleaned. My Worthington HP 100s certainly didn't say O2 clean.

See the description here: XS Scuba Worthington Cylinders HP Steel 3442 psi. Tanks It clearly states that the tanks are clean for Nitrox <= 40% - not O2 cleaned.

It's odd that my LDS takes the alternate view and does PP blending without O2 cleaning new tanks. I think they are wrong but it's their shop.

Over time, all of my tanks will be O2 cleaned with appropriate labels. Although I am PSI trained in such matters, I'm not planning to do the work. It's too cheap to pay someone else to do it. A VIZ only costs $7 - I'm not going to even lift the tank for that kind of money.

I am reluctant to have my tanks filled anywhere except the LDS where I bought them. First, I expect the tanks to stay pristine. Second, I don't know what other shops may put in them. So, if I need more tanks for an out-of-town dive, I rent them. I do NOT have my tanks filled at the dive site.

Richard

 

[cbrich]

I bought a 100CF tank, and my LDS fills it with nitrox without the added cost, but they also included the cleaning when I bought the tank. They use the partial blending method, and they don't fill outta town tanks with nitrox. Most of the dive shops in my area use partial blending method for nitrox. I don't blame a shop for not wanting to fill an unknown tank with pure oxygen and then topping it off. This is more of problem than an aluminum tank blowing up because it's an older alloy.

 

[Peter_C]

Since you live in Monterey, just go to Aquarius on Del Monte and get your tanks filled from their bank system. They have always filled my tanks, which I keep in hydro and vis. My tanks have a vis sticker that states good for 40% max oxygen that also is punched for NOT O2 CLEAN. I do not want a giant Nitrox sticker (Band) on my tanks that promotes corrosion.

FWIW I only fill my tanks with 32%, and make sure they are kept clean inside.

Aquarius on Del Monte is one of the few shops I have ever been to that posts their air test certification on the wall.

 

[Bogie]

These are the first tanks that I have ever purchased.

Nitrox Ready
Cleaned and sealed at the factory
Free of hydrocarbons to a level of 40 mg per square meter

They say Nitrox Ready which I assumed meant you can go into any shop and get them filled with up to 40% oxygen mixture. What they should state is what they are not. "Not oxygen cleaned for partial fill blending". That would clarify it. Now I know but this statement would have helped.

Thanks for your comments

 

[cmuljadi]

I bought HP80 steel Worthington from Diver Dans and they want to charge extra something like 80 bucks to make it O2 ready. I took it to Anywater and they have no issue filling 32% since they know worthington is nitrox ready and I think Anywater uses pre-blend style.

 

[Chuck Tribolet]

AWS does partial pressure blending for mixes other than 32, and I believe
banks 32.

 

[zaberman1]

My suggestion is take it to take it to a shop that really knows what they are talking about (at least to get a VIP) and pay for a VIP to detect any hydro carbons with light. IF they do, get them O2 cleaned and have them put an O2 clean sticker on it. If no visible hydrocarbons are present, an O2 clean would be rather redundant. I understand their reluctance if the shop that VIP'd the tank didn't check for hydrocarbons but hey, what can you do?

 

[rstofer]

These are the first tanks that I have ever purchased.

Nitrox Ready
Cleaned and sealed at the factory
Free of hydrocarbons to a level of 40 mg per square meter

They say Nitrox Ready which I assumed meant you can go into any shop and get them filled with up to 40% oxygen mixture. What they should state is what they are not. "Not oxygen cleaned for partial fill blending". That would clarify it. Now I know but this statement would have helped.

Thanks for your comments

A fundamental tenet of marketing is to make a negative sound like a good thing! This whole Nitrox thing has been one example of good marketing after another.

40% regulators is another example. Of course they are rated for 40%. The industry decided that ANY equipment (probably excluding Titanium regulators) is good for 40%. So are all the hoses.

Wow! My new regulator is Nitrox ready! Well, so is my 20 year old Omega II. And I guarantee it never saw clean air. The compressors on those bum boats in Malaysia always were a little iffy.

Richard

 

[Jim Lapenta]

I also want to ask if any of you have seen "O2 clean" hoses? Didn't think so. Many shops have the idea that you need those god awful looking bands on a tank that say NITROX. Truth is you don't. All you need at a shop that knows what it is doing is little sticker that says the tank is O2 clean. And one for the vis if it;s not on the same sticker. Then all you need is a piece of white duct tape with the mix, MOD, and I also put the date and fill pressure on mine. Otherwise the shop trying to sell you those big stickers is just trying to make a buck. Unless you get the ones from airspeed press that say "Voodoo Gas" or "This is Not Your Tank". Those are OK in my book.