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View Full Version : Is there a danger? Should air divers analyze thieir gas?



Splitlip
08-13-2007, 11:51
Another discussion prompted my thoughts here.

When an air diver picks up his tank or is given a tank by a charter, does he or she analyze it? From my experience the answer is no. Should it be analyzed? I think yes. Unfortunately most air divers are unaware of the potential dangers of diving air enriched with oxygen and they likely don't know what an analyzer is for nor how to use one.

At a busy fill station it is possible for an attendent to pump pure O2 into a cylinder not labled for Nitrox. In fact, some Nitrox divers get their fills in cylinders which are not labled.

Pure O2 is toxic below 20 ft. I know of an incident where in the frenzy of filling tanks during mini season, a partial blend facility pumped pure O2 in a tank and no air.
The diver who was assigned the tank did not analyze. Fortunately predive he noticed that the tank was not full and he did not dive it. It was found later that it was pure O2. It would have killed him.

Now most Nitrox divers don't trust a fill station to guarantee the 02 percentage in their tanks, why should an air diver.
I analyze avery tank I use, even if it is "air".

deepdiver47
08-13-2007, 12:03
Anything is possible. Say you get 40% nitrox put in that tank you go down on a wreck 150 ft you could be in for trouble. I'll bet they look at you funny when you check?

Warren
08-13-2007, 12:08
Newbie question.. How do you analyze it?

thesmoothdome
08-13-2007, 12:21
Most fill stations have O2 analyzers, but it's not a bad idea to have your own either. Something like this http://scubatoys.com/store/detail.asp?PRODUCT_ID=AmoxtecO2EII

deepdiver47
08-13-2007, 12:24
with an O2 analyzer, take a look at this:

http://www.scubatoys.com/store/Scuba_Nitrox.asp

WV Diver
08-13-2007, 12:59
This is why you check the qualifications and certifications of your fill station and know who you are dealing with.

I can't imagine the amount of incompetence it would take to fill an unmarked AL 80 with 100%, let alone unknowingly giving it out to a customer, not to mention who in their right mind would fill a tank with anything other than air if it was not properly designated for nitrox intentionally or otherwise.

Who was this?

TxHockeyGuy
08-13-2007, 13:11
This is why you check the qualifications and certifications of your fill station and know who you are dealing with.

I can't imagine the amount of incompetence it would take to fill an unmarked AL 80 with 100%, let alone unknowingly giving it our to a customer, not to mention who in their right mind would fill a tank with anything other than air if it was not properly designated for nitrox intentionally or otherwise.

Who was this?

Not to mention filling a non o2 clean tank with pure o2 has other possibly disastrous consequences for the fill operator (think boom for those who are not Nitrox certified). I've been considering getting an analyzer for an upcoming trip as I want to dive nitrox. I've kind of been on the bubble but the more and more I think about it the more I think I'm going to want to pick up an analyzer sometime later this week over at ScubaToys. I just wish they weren't so expensive.

RonFrank
08-13-2007, 13:18
Pure O2 is toxic below 20 ft. I know of an incident where in the frenzy of filling tanks during mini season, a partial blend facility pumped pure O2 in a tank and no air.
The diver who was assigned the tank did not analyze. Fortunately predive he noticed that the tank was not full and he did not dive it. It was found later that it was pure O2. It would have killed him.

Now most Nitrox divers don't trust a fill station to guarantee the 02 percentage in their tanks, why should an air diver.
I analyze avery tank I use, even if it is "air".

I've never seen a fill station put pure air into a NON-NITROX tank. It is a good way to.... explode! :smiley5:

Non-Nitrox divers don't use Nitrox tanks. Nitrox divers use Nitrox tanks, and they are marked. If you get a Nitrox tank as a non-Nitrox diver, than get another tank. If you are Nitrox certified, then you know the answer. NEVER dive a Nitrox tank that you have not personally verified.

Nitrox blend air is ALWAY in a different bank vs. the just air.

I don't see any valid reason for air divers to be analyzing their air.

Dive-aholic
08-13-2007, 13:49
Many shops use the same hoses for both air and nitrox. They just flip a valve to get air from one set of banks and flip it the other way for nitrox. I've seen tanks get filled with 32% when it was supposed to be air. Go below 110' with that 32% and your blowing the MOD. Personally, after reading some accounts lately of seizures occurring at ppO2 above 1.2, I adjust my MOD accordingly. If I get air fills at places where nitrox is also filled, I analyze.

Splitlip
08-13-2007, 16:11
This is why you check the qualifications and certifications of your fill station and know who you are dealing with.

I can't imagine the amount of incompetence it would take to fill an unmarked AL 80 with 100%, let alone unknowingly giving it out to a customer, not to mention who in their right mind would fill a tank with anything other than air if it was not properly designated for nitrox intentionally or otherwise.

Who was this?

The op is still around. I don't recall where the fills came from.

The tank might have been stickered "nitrox", but they don't have to be be filled with nitrox. My point is that mistakes happen and there is never a guarantee of what gas ends up in a cylinder where mixed gas is offered.

Even doctors remove the wrong limb and organs.

Less likeley to screw up in a partial blend facility I suppose, but where EANX is banked with air, it is very easy.

Splitlip
08-13-2007, 16:17
Pure O2 is toxic below 20 ft. I know of an incident where in the frenzy of filling tanks during mini season, a partial blend facility pumped pure O2 in a tank and no air.
The diver who was assigned the tank did not analyze. Fortunately predive he noticed that the tank was not full and he did not dive it. It was found later that it was pure O2. It would have killed him.

Now most Nitrox divers don't trust a fill station to guarantee the 02 percentage in their tanks, why should an air diver.
I analyze avery tank I use, even if it is "air".

I've never seen a fill station put pure air into a NON-NITROX tank. It is a good way to.... explode! :smiley5:

Non-Nitrox divers don't use Nitrox tanks. Nitrox divers use Nitrox tanks, and they are marked. If you get a Nitrox tank as a non-Nitrox diver, than get another tank. If you are Nitrox certified, then you know the answer. NEVER dive a Nitrox tank that you have not personally verified.

Nitrox blend air is ALWAY in a different bank vs. the just air.

I don't see any valid reason for air divers to be analyzing their air.

You are betting your life on the fact that the absense of a green sticker is going to protect you if you expect air? Not I.

Splitlip
08-13-2007, 16:21
Many shops use the same hoses for both air and nitrox. They just flip a valve to get air from one set of banks and flip it the other way for nitrox. I've seen tanks get filled with 32% when it was supposed to be air. Go below 110' with that 32% and your blowing the MOD. Personally, after reading some accounts lately of seizures occurring at ppO2 above 1.2, I adjust my MOD accordingly. If I get air fills at places where nitrox is also filled, I analyze.

The shops in my area which bank premix usually bank 36%. That can be more catastrophic considering the depths the local ops drop divers.
The "36%" usually varies between 35 and 37.

quarrydiver
08-13-2007, 23:00
good reason to get the nitrox cert. so you are aware of the potential dangers.

Splitlip
08-14-2007, 06:12
Pure O2 is toxic below 20 ft. I know of an incident where in the frenzy of filling tanks during mini season, a partial blend facility pumped pure O2 in a tank and no air.
The diver who was assigned the tank did not analyze. Fortunately predive he noticed that the tank was not full and he did not dive it. It was found later that it was pure O2. It would have killed him.

Now most Nitrox divers don't trust a fill station to guarantee the 02 percentage in their tanks, why should an air diver.
I analyze avery tank I use, even if it is "air".

I've never seen a fill station put pure air into a NON-NITROX tank. It is a good way to.... explode! :smiley5:

Non-Nitrox divers don't use Nitrox tanks. Nitrox divers use Nitrox tanks, and they are marked. If you get a Nitrox tank as a non-Nitrox diver, than get another tank. If you are Nitrox certified, then you know the answer. NEVER dive a Nitrox tank that you have not personally verified.

Nitrox blend air is ALWAY in a different bank vs. the just air.

I don't see any valid reason for air divers to be analyzing their air.

02 cleaned tanks don't always have nitrox stickers. Stickered tanks don't always get nitrox (unless it is 21% mix:smiley2:) and people filling tanks make mistakes.

cummings66
08-14-2007, 07:22
One of the dive shops I use uses filtered air for both regular air fills and Nitrox fills. They have a switch that goes from one side of the room to another. They take the Nitrox tanks to an area about 15 feet away and fill it with O2, then they turn that switch and fill it with air.

It's COMMON for Nitrox tanks to have no markings on them at all, many cavers and other technical divers don't mark their tanks with the big green sticker. There's usually a small tag on it saying what's in it however.

My own Nitrox tanks used to have no stickers on it, but some dive shops had issues with it so I put them on. Now some other shops have issues with that. You can't win for losing. It's like this, my VIS is due at the end of the month and I won't be diving with Nitrox until after and it will have a new O2 cleaning and all done. So I wanted regular air. This shop would not put air in because of the sticker, even after I pointed out the above facts and offered to remove the stickers. He claimed it was for my safety that he wouldn't put air in it. It wasn't compatible. Heck, it already had air in it. He was even a DM.

ParrotHead
08-14-2007, 07:42
with an O2 analyzer, take a look at this:

http://www.scubatoys.com/store/Scuba_Nitrox.asp

Great - One more thing to apply my ST Gift Card towards :smiley5:

RonFrank
08-14-2007, 11:21
My own Nitrox tanks used to have no stickers on it, but some dive shops had issues with it so I put them on. Now some other shops have issues with that. You can't win for losing. It's like this, my VIS is due at the end of the month and I won't be diving with Nitrox until after and it will have a new O2 cleaning and all done. So I wanted regular air. This shop would not put air in because of the sticker, even after I pointed out the above facts and offered to remove the stickers. He claimed it was for my safety that he wouldn't put air in it. It wasn't compatible. Heck, it already had air in it. He was even a DM.

Than find another dive shop. EVERY nitrox clean tank should be labeled. If they are not, then plan on paying for a Nitrox clean, or converting them to air only tanks.

When one wants 21% Nitrox, that shops tapes over the label (removable) indicating that the tank contains no additional O2.

In the USA, these standards are not subject to debate.

Our LDS will NOT fill a tank with Nitrox without an O2 clean sticker on it. They will NOT fill a tank with non-clean Air without removing the Nitrox stickers and labels.

One of my tanks does NOT have the big Long Green and Yellow sticker on it, but it DOES have an O2 clean sticker on it.

Anyone that pays to get a tank O2 cleaned is going to Damn well insist on an O2 clean sticker, as if they don't they will NOT be able to use Nitrox.

I've had fills done at a LOT of shops, and I have not seen a shop that delineates from these procedures.

RonFrank
08-14-2007, 11:30
02 cleaned tanks don't always have nitrox stickers. Stickered tanks don't always get nitrox (unless it is 21% mix:smiley2:) and people filling tanks make mistakes.

Who do you know that does not have the O2 clean label on a tank that has PAID to have them Nitrox cleaned? I've certainly seen tanks without the big Nitrox band, but not without the O2 clean sticker.

Any shop that puts non-clean air in a Nitrox tank is required to remove the Nitrox stickers.

These are the rules. It's in the LDS's best interest to follow them, and I have never run into a Nitrox filling LDS that fails in this regard because it can be very dangerous to fail.

Mistakes can be made. However it would be MUCH more common to screw up an O2 Clean tank by filling it with non-clean air vs. putting 100% O2 in a non-clean tank.

So are you suggesting that the diving community at large all run out and purchase analyzers and start checking their air? :smilie39:

Splitlip
08-14-2007, 11:32
My own Nitrox tanks used to have no stickers on it, but some dive shops had issues with it so I put them on. Now some other shops have issues with that. You can't win for losing. It's like this, my VIS is due at the end of the month and I won't be diving with Nitrox until after and it will have a new O2 cleaning and all done. So I wanted regular air. This shop would not put air in because of the sticker, even after I pointed out the above facts and offered to remove the stickers. He claimed it was for my safety that he wouldn't put air in it. It wasn't compatible. Heck, it already had air in it. He was even a DM.



In the USA, these standards are not subject to debate.

Anyone that pays to get a tank O2 cleaned is going to Damn well insist on an O2 clean sticker, as if they don't they will NOT be able to use Nitrox.

I've had fills done at a LOT of shops, and I have not seen a shop that delineates from these procedures.

I don't believe that to be the case.
Here is a link to Fill Express in Ft. Lauderdale.

http://www.fillexpress.com/library/fillfaq.shtml

Note the "Cylinder Contents" section. Recommended, not required.

Not trying to be argumentitive, but I think the potential for problems is possible though not likely. A nitrox diver does not trust the fill station to give the requested mix. Why should an air diver?
Note their "air fill" procedure. 21% Nitrox

Edit: Fill Express is Dive Rite Express. A major player.

Splitlip
08-14-2007, 12:13
02 cleaned tanks don't always have nitrox stickers. Stickered tanks don't always get nitrox (unless it is 21% mix:smiley2:) and people filling tanks make mistakes.

Who do you know that does not have the O2 clean label on a tank that has PAID to have them Nitrox cleaned? I've certainly seen tanks without the big Nitrox band, but not without the O2 clean sticker.

Any shop that puts non-clean air in a Nitrox tank is required to remove the Nitrox stickers.

These are the rules. It's in the LDS's best interest to follow them, and I have never run into a Nitrox filling LDS that fails in this regard because it can be very dangerous to fail.

Mistakes can be made. However it would be MUCH more common to screw up an O2 Clean tank by filling it with non-clean air vs. putting 100% O2 in a non-clean tank.

So are you suggesting that the diving community at large all run out and purchase analyzers and start checking their air? :smilie39:

The dive community can do whatever it wants. I think it is wise to analyze "air". I do. I don't own an analyzer, I use the shop's or the boats.
Please see my post just above this one.
Fill Express analyzes their own "air" fills. What does that tell us?

cgvmer
08-14-2007, 12:14
FYI: When I was in fill express renting some gear, I saw them analyze every tank they filled, including my air tanks.

BSea
08-14-2007, 12:35
I've never seen a fill station put pure air into a NON-NITROX tank. It is a good way to.... explode! :smiley5:

Non-Nitrox divers don't use Nitrox tanks. Nitrox divers use Nitrox tanks, and they are marked. If you get a Nitrox tank as a non-Nitrox diver, than get another tank. If you are Nitrox certified, then you know the answer. NEVER dive a Nitrox tank that you have not personally verified.

Nitrox blend air is ALWAY in a different bank vs. the just air.

I don't see any valid reason for air divers to be analyzing their air.
Your assuming all fill stations have banks of blended gas. That isn't true. My LDS puts pure O2 in the tank then adds 21% nitrox to give the fill desired. There is no bank fo 32% or 36%. They just bank air that is cleaned for nitox mixing. All regular tanks are filled with this clean air. So in effect they are getting 21% nitrox.

So it just depends on the fill station, and what they are set up to fill. And although I've never analyzed my non-nitrox fills, I can see that this could be something that is a valid concern. I've been places that have multiple fill whips. It would not be impossible for an overworked, operator to mix up a whip. It just takes a a minute to analyze the tank. Seems like a reasonable thing to do. Especially since more & more divers are diving nitrox.

cummings66
08-14-2007, 18:22
Than find another dive shop. EVERY nitrox clean tank should be labeled. If they are not, then plan on paying for a Nitrox clean, or converting them to air only tanks.


You misunderstood me, the sticker I am referring to is the Nitrox or Voodoo gas sticker, not the cleaning. Some shops have that sticker as part of the visual inspection sticker to make less clutter on the tank.

uzzell20
08-14-2007, 18:34
its best to anylize it yourself, but also its nice if you have a local dive shop shop you can trust, i know everyone at my shop and i know that they take pride in everything they do, i feel i am never in any trouble using them for fills

cummings66
08-14-2007, 18:39
I've never seen a fill station put pure air into a NON-NITROX tank. It is a good way to.... explode! :smiley5:

Non-Nitrox divers don't use Nitrox tanks. Nitrox divers use Nitrox tanks, and they are marked.

But on a boat when a person sees a bunch of tanks, and some of them only have the o2 clean sticker on it, no Nitrox band on it, they may accidentally grab the wrong tank. I think that's where the big scare is. I don't see it as a big possibility however, but I could see a mix up happening with a new diver who's renting tanks. An owner would never make that mistake.



Nitrox blend air is ALWAY in a different bank vs. the just air.


No, not always. I know of some shops where it's easier for them to have one bank, that bank has O2 compatible air in it. All tanks get that air, Nitrox tanks have the first step of adding O2. Economics aside, for them it's easier and has less risk of making an O2 tank dirty. In fact when they clean tanks they O2 clean every tank, only those who pay extra get the sticker and added worry. Again, they say it's easier to just treat them all as if they're using O2, so there's only one standard to follow, O2 clean.

It costs more I'm sure but that is how it's done. Everything is O2 clean. There is no dirty air anywhere around.

Splitlip
08-14-2007, 18:43
Than find another dive shop. EVERY nitrox clean tank should be labeled. If they are not, then plan on paying for a Nitrox clean, or converting them to air only tanks.


You misunderstood me, the sticker I am referring to is the Nitrox or Voodoo gas sticker, not the cleaning. Some shops have that sticker as part of the visual inspection sticker to make less clutter on the tank.

Yes. The case with mine. At most fill stations the VIP sticker is not visible once the tank is in the trough.

CompuDude
08-14-2007, 19:44
I think this is a regional issue.

Locally (SoCal, Los Angeles), few shops bank... they either PP blend into o2 clean tanks, or they have a membrane setup.

Membrane fillups are a hands-on process. Also not very easy to end up with 100%. Plus nitrox tanks are analyzed immediately afterwards, and air fills at the same shop are done with a different rig.

On boats, again, the boat is either 32% bank (and I'm diving Nitrox) or membrane, and again, that's a hands-on process that's not easily confused. We don't have a stack of tanks, each diver has their tank at their station, and it remains rigged up with their gear, in place, and gets refilled in place.

Only a few shops do PP blending around here, so not many people bother with o2 clean tanks, since 40% is the max o2 content you'll get from membrane or banked systems, and you don't need o2 clean tanks for that.

For me, I happen to always get my air fills at a local shop that doesn't even offer Nitrox. No danger of high o2 air there! The only time I take my tank to another shop is specifically for Nitrox, at which point of course I'll be analyzing it. I think most SoCal divers are in a similar situation, except for those who blend their own at home mixing stations, in which case it's all their problem.

cogrwy
04-12-2008, 22:39
Since I got Nitrox certified I have only used two local dive centers, both of which I trust. They both require Nitrox divers to personally analyze their tanks, witnessed by the filler. If I am ever fortunate enough to take a dive trip, I will have my own analyzer with me. No disrespect to out-of-town dive shops, I just choose not to take a chance.

Ohio_diver16
04-12-2008, 23:16
Call me out if I'm, "out of line," and admittedly I've yet to be NITROX certified. But isn't one of the main lessons pushed on you as a diver, "It's your responsibility!?" To err is human, and working on an overcrowded boat, or in a short-handed shop does leave one to speculate that the possibility of human error is there - But again, ultimately, just like calling a dive if need be, it's the individuals prerogative to be safe. Just my .02.

Damselfish
04-13-2008, 11:42
For various reasons, I think the odds of an air diver accidentally getting a tank of Nitrox are quite low overall. While it wouldn't hurt to analyze all tanks, I don't see it happening anytime soon, unless there is an accident that kills someone clearly traced to this occuring. I think the odds of getting a Nitrox tank with an unexpected mix are much higher.

However, I really think the OW class should cover some basics about Nitrox (and other gases.) Not the tables and all, but just what Nitrox is, why people use it, the dangers, and what to watch out for as far as not using marked tanks, or when tanks might not be marked. This would help eliminate the common confusion among new divers thinking things like Nitrox is meant to go deeper. And raise awareness among divers who might not know any better otherwise, to pay attention to what they're grabbing, and when maybe they should be more concerned and perhaps ask to see their tank analyzed, which no shop should object to.

terrillja
04-13-2008, 11:59
not to mention who in their right mind would fill a tank with anything other than air if it was not properly designated for nitrox intentionally or otherwise.


Well New England seems to be more lax as far as labeling, in fact some shops won't fill with air if there is a nitrox wrap. Generally it's pretty easy for me to get a premix nitrox fill, so I just go with that rather than O2 cleaning cylinders. Though I am thinking about getting a couple of voodoo gas stickers, partly because they talk about meeting the dark lord, so if a shop ever read it they might get a laugh.

cummings66
04-13-2008, 12:05
Another reason to analyze, if you have a steel cylinder and it has rust in it, or got water in it causing rust, you may find that in as little as a month there is not enough O2 present to support life.

There has been to my knowledge only a couple deaths related to low O2 in a steel cylinder, but it has happened.