Do you check tanks for pressure and contents before you leave the shop?

[MikeFerrara]

I think Genesis does bring up a good point. I don't think "air" tanks need to be analyzed and labeled if...

the fill process is mistake proofed. I have been in manufacturing/test engineering for a long time and we don't test for something unless we think it can happen. If we think it can happen we fix the process if we can rather than adding another process (the test) which by nature adds more oportunity for screw ups and adds cost.

If getting the wrong mix is as easy as twisting the wrong valve or grabing the wrong whip and those things are easy to do then you had better test and mark. I would rather fix/avoid the poorly designed fill station than make it a requirement that everyone analyze all tanks though.

 

[Genesis]

Has anyone seen a filling station test the mix in tanks that need to be filled to check contents from the last fill?

will all dump a tank with a Nitrox mix in it before filling it.

If they know its a Nitrox tank (e.g. its banded)

However, they will also put air in a banded Nitrox tank (OCA, one hopes if it has an O2-clean vis sticker on it!) without dumping the existing mix, which means that you could very easily end up with something "other than air" in that tank.

The point is that MOST of the time this won't matter; in fact, I suspect that a mistake of this kind (e.g. either putting EANx32 into an "air" tank, or putting air in an unmarked tank that has some FO2 in it other than 21%) happens quite frequently. SOME people probably even make it happen ON PURPOSE (e.g. PP filling a tank with O2, then taking it to an unsuspecting shop to be "topped" with air) as a means of avoiding the rapacious "uptick" that most shops apply when selling Nitrox.

Without analyzing ALL tanks there is simply no way to know when it happens, because you never detect it, and absent someone either personally testing it or diving it beyond the MOD, they would be none the wiser for the experience.

Since it only takes on "rich mix" to ruin you, however, I believe its prudent to check and mark tanks at the time of fill, since I've seen exactly how easy it is for such a mistake to be made.

 

[Ziggys_Friend]

Genesis once bubbled...
I suspect that a mistake of this kind (e.g. either putting EANx32 into an "air" tank, or putting air in an unmarked tank that has some FO2 in it other than 21%) happens quite frequently. SOME people probably even make it happen ON PURPOSE (e.g. PP filling a tank with O2, then taking it to an unsuspecting shop to be "topped" with air) as a means of avoiding the rapacious "uptick" that most shops apply when selling Nitrox.

Genesis I'm shocked, yes shocked!

You're not saying someone might do the dastardly deed of filling their own tanks with 02 (like maybe 14% of volume to make EANx32) and then have it topped off with air?

I say it again, I'm shocked!

~<//><

P.S. Of course, since YOU brought the idea up, IF someone actually did such a thing I sure hope they'd have added a bit of air from another scuba tank before bringing it in to be topped off for safety sake.

 

[MikeFerrara]

Genesis once bubbled...


will all dump a tank with a Nitrox mix in it before filling it.

If they know its a Nitrox tank (e.g. its banded)

However, they will also put air in a banded Nitrox tank (OCA, one hopes if it has an O2-clean vis sticker on it!) without dumping the existing mix, which means that you could very easily end up with something "other than air" in that tank.

The point is that MOST of the time this won't matter; in fact, I suspect that a mistake of this kind (e.g. either putting EANx32 into an "air" tank, or putting air in an unmarked tank that has some FO2 in it other than 21%) happens quite frequently. SOME people probably even make it happen ON PURPOSE (e.g. PP filling a tank with O2, then taking it to an unsuspecting shop to be "topped" with air) as a means of avoiding the rapacious "uptick" that most shops apply when selling Nitrox.

Without analyzing ALL tanks there is simply no way to know when it happens, because you never detect it, and absent someone either personally testing it or diving it beyond the MOD, they would be none the wiser for the experience.

Since it only takes on "rich mix" to ruin you, however, I believe its prudent to check and mark tanks at the time of fill, since I've seen exactly how easy it is for such a mistake to be made.

If someone has a "nitrox" tank and they want nitrox int it, I only dump what I need to in order to get the mix I'm after. I analyze the existing mix, calculate what I need and only drain what I must.

If someone wants a partial tank of nitrox topped off with air it gets analyzed and logged like any other nitrox fill.

I also don't put air through the hyper filter unless I need HP air. Therefore, if someone brings me a tank with O2 in it and they don't tell me and I find out about it I will consider it attempted murder and treat them like an attempted murderer.

 

[TheDarknessLord]

I am a Nitrox Diver, so I have to...