Clarifying Stage Bottle Markings vs Deco Bottle Markings

Stage Bottles are generally a larger volume Aluminum bottle (80cft/11L) that we fill with the same gas as our backgas for that particular dive. In other words it is a standardized bottom gas that is safe to breath at the deepest depth you will be diving and is really an extension of the “back gas.” It is always breathable during the dive and therefore there is no risk of switching to it even if by accident.

Therefore it is filled, analyzed and marked the same as you would the backgas. A stage however is rigged differently than the backgas as it has a single first and second stage regulator and therefore is not sharable. You can donate it because of the 40" hose but eventually the OOA diver must end up on your long hose as the stage is not designed to be sharable. That being said, they are always used first (before the backgas) leaving the backgas as the donatable and sharable source or "bailout." Therefore in UTD we treated the stage as part of the backgas (including volume calculations) and therefore there no permanent marking necessary. Remember they are safe to breath at any depth.

So let's look at some of the reasons why we do not mark the stage bottles with permanent markings

They are safe to breath at max depth.
They will not be taken deeper they they can be breathed form an PPO2 point of view and/or and END point of view as they are the same as backgas.
Switching to them is not dangerous at point during the dive.
They are always filled and used with the deepest standardize gases.
They are filled with a different standardized mixes for different dives and depths.
They are used first from the beginning of the dive and therefore you are not “switching” to them during the deco .
By not marking them you are reducing the confusion with deco bottles
If you were to mark them which PPO2 do you use ? (Industry std 1.4, UTD/DIR short duration dive 1.2, UTD/DIR long duration dive 0.7 or traditional 1.6)
Historically MOD stickers were used to indicate max operating depth of the bottle based on O2 content not on Narcotic depth. So a 100'/30m marking for Nitrox 32% is confusing as it safe to breath from a O2 perspective but because of our Narcotic belief we limit it to that depth. Remember it can be breathed at 111'/33m if using 1.4 or 132'/40m if using 1.6 and 39'/11m for 0.7 or 90'/27m if using 1.2. See the issues here. O2 is far more risk than narcosis. There is no real narcosis MOD stickers
Why mark a stage bottle? A Deco Bottle is makes sense to permanently mark. Why? Because generally it can and is carried deeper than the mix will allow one to breath it safely from an PPO2 point of view. Meaning the O2 content in that bottle is unsafe to breath beyond a certain depth and therefore that depth should be clearly visible on the tank and when switching to it is dangerous and therefore done as a team and your teammates can clearly see the bottles markings. Generally the accepted PPO2 for a deco bottle is 1.6 and therefore needs to be clearly marked for both the diver and the team mate. Whether you are using it as a travel or just strict as a deco bottle, you need to permanently mark it because you will be carrying it deeper than it is safe to use.

To summarize, UTD's position is that we do not permanently mark our “Stage” bottle with an MOD sticker (our initials are fine) as we fill and analyze them with the same bottom gas as the backgas that we are using for that dive. If the gas in the bottle is different than that of the backgas, then we considered it to be a “Deco” bottle and should be treated accordingly. Remember, the bottle is consider a deco bottle if the gas contents contained in the bottle has a PPO2 greater than 1.6 at depth. A “Deco” bottle is fill, analyze and Permanently Marked with the MOD sticker that indicates the max depth the bottle can be breathed with a PPO2 of 1.6. So, in UTD we have a 240’/72m bottle, 190’/57m bottle, 120’/36m bottle, a 70’/21m bottle and an Oxygen (O2) 20’/6m bottle. These are our standardize “Deco” mixes.

I sincerely hope this clarifies UTD’s position on Stage Bottle markings.

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Comment by Peter Steinhoff on June 7, 2010 at 5:45pm: Hi Andrew and everybody else!

I have though about this a lot and I've found that many people are actually confusing MOD with gas content.

MOD is a safety measure, a cross check, to give your buddy a second chance to save your life should you make a mistake identifying the proper bottle and start breathing from it. It's not a gas content sticker. It doesn't in itself represent a particular gas, a maximum PO2 or maximum END. It only represents the maximum operating depth for that bottle.

Removing that safety check on a stage bottle doesn't sound like something that will increase safety in any way or shape. Sure, in many cases the stage bottles might contain the same gas as your doubles but that is not always the case. And if you own several stage bottles, each containing different gases, you would increase the risk of bringing a shallower bottle with your instead of the one you intended - even for a simple dive.

The mix up might happen on the boat, it might happen when you load your car, it might happen because you are in hurry. Hopefully you would catch it before starting to breath from the bottle under water but if you don't, your buddy can't catch it. There is no one to correct your mistake. And what would the benefit consist of? Convenience on land?

If the regular MOD stickers are too hard (and/or expensive) to change on different dives using the same stages then just use regular Avery L4775/L4774 polyester labels instead. Sure, they won't hold up as long as commercial MOD stickers but they hold up pretty good anyway and they are not hard to replace.

Of course Andrew, you are free to decide whatever you choose for UTD, but I hope you might reconsider this in the future as I think non-marked stage bottles might actually open up for more "breathing the wrong gas"-scenarios and not less.

Take care.

Peter

Comment by Andrew Georgitsis on May 13, 2010 at 10:27pm: Rich

There is a UTD standard and that is no permanent stage marking as the only thing needed and used to identify what the gas contents of it is the analyzation and the analyzation tape markings and one should not the rely on the MOD stickers on the side as it is confusing.

Andrew

Comment by Nick Ambrose on May 13, 2010 at 11:44am: Well, I can see Andrews point. You cannot put 21/35 in that 190 bottle and then use it as a stage because it's too narcotic.

You also can't just put 18/45 (which would work for a stage) because thats not the correct 190 deco gas....

Comment by Richard on May 13, 2010 at 10:53am: MOD is the depth the gas is trying actively to kill me. Not 1/3rd of an ATA extra narcosis. The exception being 32% (100ft) because 111ft is just silly.

Considering you have a 157 pages of standards & proceedures so far, it seems a bit of a stretch that you can't come up with a standard MOD labeling scheme. For instance, UTD's MODs are listed on page 137 and 21/35 is even currently shown as 190ft.

Comment by Andrew Georgitsis on May 13, 2010 at 10:40am: Rich

What I am resistant to is introducing into the community even more confusing markings for people to try to figure out. The idea of keeping the bottles clean and free and any unnecessary markings is important to me. That is why we remove nitrox and trimix markings.

As a side note: In your image below the 190 bottle, I assume is OK to use at 190'/57m. Although from your example your gas selection of 21/35 in that bottle is not... It may be O2 wise but not narcotic wise. The narcotic formula of 1-Fhe * ATA gives 21/35 at 190'/57m a narcotic value of 4.3 ata or 110' which I am not willing to accept as a standardize breathable gas. It should be 18/45 in the tank. So which is it in that tank for tomorrows dive 21/35 or 18/45. Oh and if it is 18/45 then what PPO2 did you mark because according to your earlier post it should be 1.4 however on your dive tommorow you will probably keep it 1.2. SEE THE CONFUSION. . However a 70'/21m bottle marked is clearly nitrox 50.

Comment by Richard on May 13, 2010 at 10:23am: The huge exception you are missing is when you get the wrong one passed to you off the boat. Yes we dive 21/35 to 150ft (using BG + a stage) and then 32% in a stage for a second dive. Then repeat the next day with the same set of doubles because there aren't any fills available. That second stage is not breathable on the first dive. It amazes me how resistant you are to be able to buddy check & verify gases easier and at any time. Not to mention the inconsistency with established cave practices. Really for zero value except to be different and contrarian.

Properly labeled cylinders for tomorrow, analysis tape on crown & MOD on the sides.

Comment by Nick Ambrose on May 13, 2010 at 10:22am: OK, at the risk of making this (even more) tortured, lets take a real example maybe.

You are in mx at the nohoch main entrance and want to dive the Blue Abyss (even though recently a shorter way opened up)

so it's 11,00 feet double scooter, double stage dive as far as I am aware, at an average of maybe 18-22 feet of depth.

Then you hit the abyss, and all you know here is that it disappears down to 200+

You want to explore the abyss.

Do you now really do the shallow portion of the dive on unmarked 15/55 or 12/65 stages, just to avoid confusing those bottles with any stages you need for the deep portion (since you are diving AL8s you will need deep stages)

I agree this is an edge case, but it's a real one.

Comment by Andrew Georgitsis on May 13, 2010 at 12:31am: Richard quoted "The logical answer to mark your stages so when I pass one to you: 1) your buddy can readily confirm that you are breathing a suitable gas at any time and 2) you get one (of potentially many) that won't kill you."

Richard, I completely fail to see your logic in the above quote. Once again ALL Deco is labeled as it is carried deeper than can be used and will kill you if breathed at max depth or depths greater than marked. ALL stages are NOT labeled because they can be breathed at all depths and you should not be going beyond your desired MAX depth, same as your backgas, and therefore by default of not being marked, you can breathe at any depth as they will not kill you. See... the logic here. They CAN BE BREATHED AT ANY DEPTH THEREFORE NO WARNING or MARKING NEEDED. They are breathable.

By your logic above we should then also MARK our backgas tanks with "WHITE DUCT TAPE" on the tanks and sharpie mark (Black permanent marker) the MOD so that "your buddy can readily confirm that you are breathing suitable gas at any time" :) Your logic of marking bottom gas just does not make sense to me.

Andrew

Comment by George K. Watson on May 12, 2010 at 9:43pm: Modulo Nick Ambrose's comment,

"The logical answer to mark your stages so when I pass one to you: 1) your buddy can readily confirm that you are breathing a suitable gas at any time and 2) you get one (of potentially many) that won't kill you"

The stages are marked. By not being marked. It's pretty simple, really.

Comment by Richard on May 12, 2010 at 12:31pm: Talk about spurious logic. The gentleman I went halibut spearing with on Partridge Bank last weekend had a puffy jacket-like BC and tank boots on his double 100s. And some wacky hose lengths too. He has his shit together, so none of it fazed me in the least because I knew he wasn't going to go tox on me because of it.

The logical answer to mark your stages so when I pass one to you: 1) your buddy can readily confirm that you are breathing a suitable gas at any time and 2) you get one (of potentially many) that won't kill you.

You (AG) obviously feel strongly about what the DIR community consensus considers labeling laziness - as evidenced on the DMX thread for instance. Sad that minty fresh UTD Tech2 students will need to be told that some of the UTD standards are not "best practices". GUE has some "unique" practices which don't work for us here either, so you are in good company.

I suppose I'll need to discuss to mark a bottom stage anyway, so its not a big deal to address the why's at the same time. So far everyone sees the value and none (except you AG) see a drawback to (e.g.) ppO2 1.4 labeling with mailbox letters or white duct tape & sharpie.