Question about my new steel tank (new to me).

[markmud]

Face palm on the "pre-blended" part by XS Scuba. But the real point is that they note the cylinder is oxygen cleaned.

Please edumacate me. Where does it say O² clean? If they are, I wasted money getting a two brand new tanks O² cleaned when they were already O² clean.

I believe they are prepped for Nitrox to 40%. Not O² clean. According to my LDS of record.

My regulators weren't O² clean when I bought them, but they are compatible with Nitrox to 40%.

What am I missing here? I was taught that there was a distinction. Furthermore, aren't tanks shipped with the valve off; therefore, they are no longer considered O² clean or VISsed for that matter? I have read that tanks are cleaned by the manufacturer to remove hydrocarbons, but does the valve have Viton O-rings verses Buna-n O-rings and Christo lube instead of silicone grease? Depends on the valve specs, right? Buna-n O-rings and silicone grease are fine to 40%.

I am not trying to be a jerk here.

Through fifteen years of dealing with nitrox, and getting pre-blended nitrox from NuVair systems (no it is not banked; they are demand systems on the boats I have been on), I have not had these issues. Are the standards different in your area? No O² clean tanks required on these boats. I think two SoCal boats do partial pressure blending, they require O² clean.

Although I do note that the differences here are much smaller at 5x for CO and 2x for CO2, vs 50x for hydrocarbons, the less crap in there the better if you ask me.

There is a person who looms very large on SB, who has written about an incident where he lent out his O² clean tanks. The borrower used someone's backyard compressor to fill them. When the owner used partial pressure blending for nitrox, the theory is the O² reacted with the hydrocarbons and created CO in the tank. I don't think the theory has been refuted. From my fourth grade education, it seems completely plausible.

What say you @dead dog, my bird of a feather? Us forth graders need to stick to gether!

cheers,
m

 

[SandyRobinson]

Please edumacate me. Where does it say O² clean...

I think the wording on the XS Scuba website could be clearer. It says the tanks are "Oxygen cleaned for use with up to 40% pre-blended Nitrox". In my way of thinking and training, the term oxygen cleaned should be reserved for cylinders where 41 to 100% O2 is being used - partial blending or deco gas. It may be more accurate to say "clean enough" or "prepped" as you mentioned. No way I would ask anyone to partial blend in these tanks.

Curiosity question for the public. My fills are generally in north Florida with banked or pre-blended nitrox. Do your shops used use these methods or partial pressure? Wondering how many of you have to keep up with oxygen cleaning of your tanks. I do not have to worry about it except for my deco bottle.

Thanks all.

 

[markmud]

Do your shops used use these methods or partial pressure?

Hi carobinsoniv,

I had one shop that partial pressure blended in Sacramento. The rest had banked nitrox. The one LDS used partial pressure blending because they had a somewhat sizeable tech community involved.

One dive site in OH uses partial pressure blending.

I had to have an O² clean tank for nitrox fills from that LDS only. I got up to 40% EANx at shops close by without O² clean.

The boats that I dived (dove?) in SoCal all had NuVair systems. For those that are not familiar with NuVair systems, the NuVair filters out nitrogen from atmospheric air. It produces EANx at a little above 1ATA. Then, it feeds its product into the intake of the HP compressor. The HP compressor compresses the EANx and fills your tank. On the boats I dove (dived) from, they did not bank nitrox, or any gas, and they did not have tanks of O².

Crew members on three boats showed me the systems and tried to explain it to me. One showed me literature from the NuVair system.

Again, there is a caveat with my post, this is a thumbnail of the process. If you find grammatical errors, spelling errors, or my nomenclature is not quite right, please don't use the cat o' nine tails on me.

cheers,
m

 

[SandyRobinson]

Hi carobinsoniv,

I had one shop that partial pressure blended in Sacramento. The rest had banked nitrox. The one LDS used partial pressure blending because they had a somewhat sizeable tech community involved.

One dive site in OH uses partial pressure blending.

I had to have an O² clean tank for nitrox fills from that LDS only. I got up to 40% EANx at shops close by without O² clean.

The boats that I dived (dove?) in SoCal all had NuVair systems. For those that are not familiar with NuVair systems, the NuVair filters out nitrogen from atmospheric air. It produces EANx at a little above 1ATA. Then, it feeds its product into the intake of the HP compressor. The HP compressor compresses the EANx and fills your tank. On the boats I dove (dived) from, they did not bank nitrox, or any gas, and they did not have tanks of O².

Crew members on three boats showed me the systems and tried to explain it to me. One showed me literature from the NuVair system.

Again, there is a caveat with my post, this is a thumbnail of the process. If you find grammatical errors, spelling errors, or my nomenclature is not quite right, please don't use the cat o' nine tails on me.

cheers,
m

Thanks Mark, If anyone knows of a spellcheck on SB, let me know. I have to read my posts about 5 times before hitting post.

 

[Scared Silly]

Please edumacate me. Where does it say O² clean? If they are, I wasted money getting a two brand new tanks O² cleaned when they were already O² clean.

As I noted from their web site:

Steel Cylinders — XS Scuba

Luxfer-Cylinders-Aluminum — XS Scuba

Through fifteen years of dealing with nitrox, and getting pre-blended nitrox from NuVair systems

Nuvair's system produces on-demand NITROX, not pre-blended NITROX. Terminology is everything.

What is missing is that this whole issue of premixed, banked, etc would go away if the !@#$ scuba industry would follow the CGA industry standards instead of making up BS.

 

[rnln]

Hi guys,
I thought I am done with tank's questions but I just discovered that my "new" tank is leaking. I had it pump to full, played with it a bit the next day and found that I had only 1800psi so thought I purged too much air out of it. I went back and got another pump to fill it up to full again, ready for the coming up dive. Left it in the garage untouched for over a week? Now it only has 800psi. Dipping it into a big bucket of water, I found that it is leaking at the over-pressure-release bolt (is it what it's called?).
Can I just go ahead and tight it up until it stop leaking?

Does the visual inspection task including checking on leak?

Good thing I didn't take it to the beach than find out that I only have 800psi in my tank :lol:

Thanks in advance.

 

[grf88]

The torque spec for the burst disk is typically between 100 and 120 in pounds. They often need to be tightened up a little but don't go crazy. If it still leaks it needs replacing.

 

[rnln]

Thanks grf88,
wow, it really needs to go up pass 100 foot lbs?
Do I have to empty the tank to tight it up? Another word, should I try tighting it with 800psi air in there? I am trying to see if I can shortcut, instead of emptying the tank tight it up, go pump, go home test leak... and may have to repeat again

 

[Ouvea]

Thanks grf88,
wow, it really needs to go up pass 100 foot lbs?
Do I have to empty the tank to tight it up? Another word, should I try tighting it with 800psi air in there? I am trying to see if I can shortcut, instead of emptying the tank tight it up, go pump, go home test leak... and may have to repeat again

rnln:

grf88 stated 100-120 Inch/Lb, not FT/Lb. Huge difference between each. At 100-120FT/Lb that's more than what you torque the lug nuts of the average sedan.

O

 

[grf88]

100 ft lbs would shear it right off.