THAT is a very interesting question! Not such a big deal with banked 32 but a really big deal for PP blenders.
Richard
No doubt, with PP blending the valve and cylinder see 100% and must be properly prepared and maintained for pure oxygen service.
Damn, all the focus is on the tank which is the least of the HP O2 issue. It's the
valve that is of most concern, not that damn tank.
If the valve is where heating will occur and it the biggest concern with HP O2. The tank is of secondary to little concern to me.
A dive shop wants to charge money to light up the inside of the tank with UV which will show them squat.. and probably ignore the most important part, the VALVE. RUN AWAY!
Frankly, if a shop requires me to have a big nitrox sticker then that shop does not get my money. (side rant )
Good point about the valve, and yes ... I'd leave that shop, either they don't know any better or they're ripping me off and I want no part of either. As far as "wraps" are concerned, proper labeling and identification of breathing media is important and needs to be considered. Frankly, when I'm getting a fill at a shop that has a single system to pump air and EAN, I analyze, even if I just ordered air.
If you walk into an ANDI shop and they start spouting "SafeAir" they are really talking about ultra pure Grade E breathing air, oxygen cleaned cylinders and oxygen built/clean valves and regulators.
Yes, it is overkill for the mainstream recreational scuba industry. Is it overkill for the technical/trimix espiring scuba diver? Maybe not.
It is not overkill for anything above 40% (well, technically it is overkill since the real "safe" figure is well above 40%), I'd even be happy with a little extra margin and be willing to make the make the break at 32%, since that gives a
ppO
2 of 1.6 at the 130FSW "sports diving limit."
I think it is better to have you equipment rigged, cleaned and upgraded for the most demanding situation you are moving toward. In this case partial pressure Nitrox blending, which is the standard ANDI method of making Nitrox fills.
For sports diving partial pressure Nitrox blending is becoming a thing of the past. For more demanding diving partial pressure is a necessity and requires oxygen service cleaning.
Is an oxygen clean cylinder and valve necessary for a Nitrox fill off a banked (i.e. pre-mixed) Nitrox supply? No, it is not necessary.
We agree.
Do ALL scuba shops that offer Nitrox, especially any percentage you might want, use banked mixes, no. Therefore having your gear oxygen cleaned and built with oxygen service parts is a good precationary measure because you might not fill at the same shop every time.
Most do, and I am much more confident getting banked NITOX than relying on shop personnel, who vary from master blenders to tank monkeys for partial pressure blending.
Physics is physics, oxygen under high pressure does weired and some what dangerous stuff. I'm not so sure that arguing aginst clean gear and cylinder content marking is such a good thing when you are dealing with the general public (i.e. mainstream scuba divers). That little peice of duct tape your write the MOD for a cylinder on might be ok for you, but what about the poor smuck resort diver that grabbs a cylinder of mix because it looks just like all the other cylinders laying around, except for that little peice of tape that got stuck to it? Mistakes in diving occur, lets promote procedures to minimize them instead of denouncing everything because it is more expensive.
I believe in good lableing, but what is the WORST thing that going to happen if the "poor schmuck resort diver" grabs a tank of 36 and goes out on a dive? If the dive is to less than 100 fsw, it's not an issue, if it's to 130 the diver should be more than a "poor schmuck" and know better; but, in any case, the diver will spike to 1.8 for 10 minutes or less. That's rather unlike to result in oxtox nor does it run run the oxygen clock very far.
...
Thal tossed out "just fill from banked 32%" This implys that cleaning your cylinder and valve is unnecessary because it is safe if you fill from a pre-mixed source.
I hope that's not what I said or implied. Please permit me to restate: If you are filling at 40% or less there is no need for oxygen cleaning or maintaining the tank and valve for oxygen service.
If you don't want to abide by the industry standard for safety, no one is going to stop you. There is no regulation or law aginst it.
What I object to is the use of "industry standards" or "insurance requirements" as a way to keep divers captive to a single supplier or to change them an extra $20 to look in the tank.