POLL, Nitrox tank use and analyze

[DevonDiver]

offcourse NOT !
in your specific example they have no nitrox capable filling station, just a normal air compressor,
so in THAT case all tanks are safe to use as AIR..

So what happens on the rare occasion that a guest diver brings their own nitrox tanks onto that boat.. but only marks them with a bit of tape (that may fall off, or may not be recognised by other customers)?

...because the only difference between that nitrox tank...and any other air tank on the boat is what? A piece of tape?

feet and meters.. you can label your MOD in micrometers if you want,
it is YOUR tank, your name, and your % O2 label on the tank too,
I prefer to just write the % and nothing more, since I use a computer on ALL dives no matter what,
so my MOD is handeled by my computer, I did verify its calculations match my book of nitrox visdom,
if my computer brakes down, I dont dive, or dive ultra conservative after tables

The point being... would a non-nitrox trained diver understand what that label meant?

Would it deter them from accidentally using it... if the cylinder was to all other specifications identical to the air tanks that they help themselves to on the boat?

 

[RonFrank]

With most things, I let it slide. If I have to use a a crappy wetsuit (cold) because I rip a drysuit seal for example... But when it comes to what I breath I NEVER do a trust me dive with Nitrox. I will take the word of a close friend (not a stranger), but my gas is checked....

 

[Randy43068]

Often I don't actually test it personally, however, I witness the test and go from there.

 

[RonFrank]

Hmmm all this speculation over personal tanks...Or tanks that are checked out to the individual. The reality is that personal tanks and tanks checked out to an individual are Not going to be then grabbed by folks by mistake. Sure it can happen, but if the guy grabbing someones tank doesn't realize it the guy who owns/rented the tanks should.

Then there is a Nitrox sticker labeling the tank. Your tanks go side by side in your space. If you do not have room for the second tank, the boat generally has a method for keeping track. Heck a lot of boats make you write down tank numbers and they check that.

The bottom line is there are a lot of things that ops do to prevent uses from mixing up the tanks. If you are hell bent on screwing up its possible, but not with my tanks!

 

[Mossman]

Hmmm all this speculation over personal tanks...Or tanks that are checked out to the individual. The reality is that personal tanks and tanks checked out to an individual are Not going to be then grabbed by folks by mistake. Sure it can happen, but if the guy grabbing someones tank doesn't realize it the guy who owns/rented the tanks should.

An example of how it could happen is if the diver with the unmarked nitrox tank decides to sit out the second dive for whatever reason and takes a nap.

Then there is a Nitrox sticker labeling the tank. Your tanks go side by side in your space. If you do not have room for the second tank, the boat generally has a method for keeping track. Heck a lot of boats make you write down tank numbers and they check that.

The reason why this is an issue is become some tanks don't have nitrox stickers labeling the tanks, just a piece of masking tape that could go ignored. You are over-generalizing about how the tanks are stored on the boat. There are lots of different types of dive boats out there and lots of different ways to store tanks on them.

The bottom line is there are a lot of things that ops do to prevent uses from mixing up the tanks. If you are hell bent on screwing up its possible, but not with my tanks!

A dive op that supplies the tanks and sets up the divers' gear on the tanks, etc., will hopefully be making sure each diver gets the appropriate tank. But mistakes can happen.

The issue is more likely to crop up on self-service dive boats popular in California, Florida, etc., where the dive boat is merely supplying a ride to the dive site and divers either bring their own tanks or arrange to rent them from the boat. If there are a lot of new/tourist divers renting tanks from the boat and other divers bringing unmarked nitrox tanks (except for a piece of masking tape) that sufficiently resemble the boat's tanks, there is definitely the potential for confusion.

 

[RonFrank]

I have dove a few different boats out of Venice/LA/San Diego. I have dove a bunch of boats from Jupiter to the Keys (FL). I've borrowed tanks from friends. I've rented tanks from Dive Shops. I've rented tanks from the boats. I'VE had Steel 100's, steel 130's, steel 75's and of course AL80's. I have had tanks with Nitrox stickers from top to bottom, and Nitrox tanks with little in the way of markings. I've been on crowed boats, and empty boats. I've been late and almost missed the boat.

What I have never had is people using my tanks by mistake. I won't let it happen, and honestly I've never had someone try to use my tank unless we agreed that what they were going to do.

Maybe I am an anomaly, maybe I'm lucky but I don't think so. You can try and convince me that this happens all the time, but that is not my experience, not once. My experience is that most folks are not diving nitrox, and if they are, they are careful. In CA so many divers dive their own tanks it's hard to find rentals on some boats....I had no idea... but you think those folks are going to get their tanks mixed up?

Tell me I am wrong but my experience says otherwise, and it involves hundreds of dives likely half or more deep and on nitrox.

 

[Mossman]

What I have never had is people using my tanks by mistake. I won't let it happen, and honestly I've never had someone try to use my tank unless we agreed that what they were going to do.

Maybe I am an anomaly, maybe I'm lucky but I don't think so. You can try and convince me that this happens all the time, but that is not my experience, not once. My experience is that most folks are not diving nitrox, and if they are, they are careful. In CA so many divers dive their own tanks it's hard to find rentals on some boats....I had no idea... but you think those folks are going to get their tanks mixed up?

Many California dive boats occasionally host dive shop groups from out of area and will supply tanks on request. California is probably a bad example, though, because these boats also usually have on-board compressors, so it's only one tank per diver.

Where it's just a ride to the dive site sort of boat in Florida, however, some boats will provide tanks for divers without them (lots of visiting divers to Florida that don't bring their own tanks) and lack on-board compressors, so each diver will have two tanks for a two-dive trip.

Now I know you are ever-vigilant and would never let anyone use your tank accidentally, but let's take a less vigilant diver. Maybe the diver gets seasick, or has some vertigo or something from the first dive and decides to sit out the second dive. He takes a nap since there's not much else to do on a dive boat when you're not feeling well and diving makes you tired. Napping during a surface interval is hardly a phenomenon and it's likely no one would bother to wake him up if he's indicated he's sitting out the next dive.

So now the tourist divers are getting ready for their second dive, and one of them notices his second tank is empty or has a low fill. That diver spies your unmarked nitrox tank that looks the same as all the others and decides, heck he'll never know 'cause he's sleeping, and swaps tanks with yours. Excuse me, not yours, I meant the diver who is less vigilant than you. For all the tourist diver knows, you've rented the same tank he has because they look the same, except for that piece of masking tape with some numbers on it. He has air, so you have air. You're not diving the second dive, so what's the worry?

He grabs your tank, dives, and dies. (Not you, of course, because you are ever-vigilant, I was referring to that other, less-vigilant diver who got seasick and took a nap.)

All it might have taken to save a life is one sticker with NITROX boldly displayed in green and yellow. That's all.

No one says "this happens all the time". Lots of dive accidents don't happen all the time. But dive accidents that are preventable by simple cautionary measures are stupid accidents. And this sort of accident certainly can happen.

 

[JS1scuba]

This has been an interesting thread. Let me toss in my $10 bucks worth. I've authored four books and a few dozen papers on this topic.

When oxygen enriched air was introduced to recreational divers in the late 1980s the standard of operation what that provided by the NOAA Diving Program. That standard required the following:

Oxygen Enriched Air Cylinders be:
a: cleaned for oxygen service if mixing was from pure oxygen and air
b: yellow in color with a green crown
c: 2" letters under the crown with the word NITROX or ENRICHED AIR NITROX
d: Cylinder contents label indicating DATE, Oxygen %, MOD at 1.6 atm, Users Initials

For Analysis they required the gas to be analyzed by two "in-line" oxygen analyzers that were calibrated at no more than 2lpm with AIR. The same sample device was to be used to sample the oxygen enriched air.

This was not overly difficult to do. It took a little prep and dedication of cylinders and required a proper investment in analysis equipment.

Once Nitrox entered recreational diving arena the "industry" made some modifications to this by concensus between the two "nitrox" agencies at the time. ANDI and IAND (Now IANTD) and then TDI, NAUI and PADI and SSI followed soon along. (PADI messed around with the 1.4 / 1.6 mess but 1.6 is the true MOD. )

The above was changed only so that the cylinder did not need to have a green crown and could be other color so long as the cylinder had a "wrap with a 1" yellow band top and bottom with a 2" band of green with the words NITROX or ENRICHED AIR NITROX on it.

This standard is still in place today. As cylinder were used with mixes other than nitrox the labeling expanded.

For Oxygen: Cylinders were to be dedicated to 100% oxygen with 2" letters of the word OXYGEN either around the cylinder head or down the trunk of the cylinder.

For Trimix : a Cylinder Wrap indicating SPECIAL MIX plus analysis.

In the mid 1990s the WKPP instituted their own in-house labeling system for their own projects. It was unique and quite efficient. They wanted minimal infomation on the cylinders but requred them to be dedicated:

2" high numbers at BASE of cylinder indicating the MOD of the gas in the cylinder: 20, 70, 130, 190, 230, 300 etc.
1" high numbers on the CROWN of the cylinder indicating the MOD of the gas in the cylinder.
Cylinder Contents tape on crown of cylinder with Mixture and initials.
For doubles it was 2" high numbers of the MOD on the left and right cylinder with Contents tape on crown.
for oxygen the word OXYGEN had to run along the trunk of the cylinder as well.

All of the above methods also require a valid Visual Inspection Sticker as well.

This became a widely used method. However many dive centers because of their agency affiliation still require a cylinder contents wrap for "recreational" nitrox cylinders as that labeling convention is part of their agency materials for gas mixing and standards of operation. It also clearly differentiates them from air cylinders.

In my own stable of cylinders we have our "recreational nitrox" cylinders with wraps and all else are with the MOD at base approach on dedicated cylinders.

In some locations you will find a modification to the NITROX at the top of the cylinder in that they put it at the bottom - this was first done in 1998 when I installed a nitrox system at Toucan Diving in Bonaire. The first 50 tanks we put lables on the top got trashed in the first week of operations on boats with BCS going on and off 6x a day. So we move the label to the bottom. This became used all over the Caribean fairly quickly.

Whatever method of labeling you use it must be CLEAR and CONCISE and one that someone other than you can understand easily. To that end using one of the two STANDARD methods of labeling would be most appropriate.

As to Analysis.

Bottom line is this. As a user you are to either analyze the cylinder personally or witness the analysis prior to using the cylinder. If you are not comfortable with an analyzer then ask to be shown how to use one. It's not that difficult. And, in fact that few minutes it takes to do it will provide you with a pause in your planning process.

There have in fact been accidents caused by a diver breathing a mixture that was improperly labled or where they inadvertantly used a wrong mixture. Accidents happen. The process of proper analysis and labeling is a step in the right direction for the diver to be aware of her mixture prior to diving so they can make the appropriate plan for the dive.

When it comes to diving with gases other than air you must be vigilant to your safety and others around you.

Regards,

 

[lowviz]

Agree. Interesting path that this thread has taken.

Total non-issue where and how I dive, but I'm now sensitized to the fact that if I ever get onto a vacation boat (no disrespect) I'll buy a few of the green and yellow stickers beforehand just to keep from having an issue with anybody. I always thought that the green and yellow banners were just brag stickers. No prob, I can abide. But WTF, an MOD rating actually means something important underwater, that one ain't coming off.

 

[lowviz]

...//....Whatever method of labeling you use it must be CLEAR and CONCISE and one that someone other than you can understand easily. To that end using one of the two STANDARD methods of labeling would be most appropriate. ....//....

I'm taking this as the definitive post on this thread. Many will disagree, but this is my new norm.