Permanent MOD markings on tanks

In an accident analysis thread, a participant made a point that permanent markings and not temporary markings should be used to identify scuba tank contents.

I believe this practice got kick started with the WKPP project and it proved to be a safe way (combined with operational procedures) to execute complex dives involving various travel, bottom and deco mixes.

Many people seem to have adopted this practice only partially. While diving at Ginnie and Peacock mostly in the last couple of years, I saw tanks with all sorts of MOD that made me believe they were not dedicated tanks. At Ginnie, in my last two trips, I noticed stages with MODs from 70 feet to 130. I rented myself a 100 foot tank that was not filled with EAN 34.

My practice when cave diving (single gas + o2) is to analyze all main, stage and deco bottles when the gear is setted up (on stages, I analyze when ready to install my regulator). On Caribbean dive trips, I analyze, mark and log analyses as per recreational standards.

Am I alone feeling that permanently marked tanks are not dedicated in real life?

I own enough tanks to permanently mark them for all the gases I use. Al80s are cheap. I believe that if one is going to be doing dives involving multiple tanks, its worth the cost to buy and dedicate tanks for each specific gas.

I also analyze at the fill station. I don't take a tank out of the fill area that isn't analyzed, taped, and marked with the o2 content, date, and my initials.

There is only two pieces of information I need on a tank when I dive and that is my name and the MOD.

Any more than that is unnecessary and can lead to confusion whilst diving.

They are placed on the tank using a Permanent Black Wide-tip Marker after the tank is analysed.

If need be, with solvent the markings can be easily removed, and new markings placed on the tank (or refresh the old ones as needed by running the black marker on top of the existing writing).

My favourite place to mark the tanks is on the neck nearer to the valve.

Not exactly DIR, but it works (for me).

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Originally Posted by PfcAJ

I own enough tanks to permanently mark them for all the gases I use. Al80s are cheap. I believe that if one is going to be doing dives involving multiple tanks, its worth the cost to buy and dedicate tanks for each specific gas.

I also analyze at the fill station. I don't take a tank out of the fill area that isn't analyzed, taped, and marked with the o2 content, date, and my initials.

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Same here.


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interesting thought Gianaameri.

My bottom mix tanks have no permanent markings regarding content. They could be anything from Nitrox to Air to Hypoxic. My stage tanks have permanent MOD markings (one on side of tank and another at neck) and are filled only with the gas for that MOD. My deco tanks are likewise permanently marked in large numerals (and the word "oxygen"). The exact percentage on all of them is marked on duct tape. Of course they all get analyzed just before diving them to verify actual contents, including CO analyzer. It's what I was taught to do by TDI and the NACD (except the CO, I added that after the brandon accident).

skip

When people talk about MOD markings, I have learned that they don't necessarily mean the same thing. MOD is determined at a particular pO2. Some people mark their tanks for MOD at 1.4. Others at 1.6. I even know someone who marks his for 2.0. For this reason, my tanks do not have permanent markings. Gaffers tape and a Sharpie work fine. Most of the time I only label the mix and can do the math in my head. If I do mark MOD, they are marked "[email protected]". If I lend a tank or swap with someone, I want them to know.

Now everyone can feel free to tell me what a moron I am.

Ken, I don't think that is a moronic method at all.... At least with duct tape, you analyze the gas, write down your findings, with the date and time....A TANK MISSING DUCT TAPE???? ANALYZE IT AGAIN !!!!!! It seems to me, permanent MOD markings that you placed on a tank 2 or 3 years ago might get ya killed

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Originally Posted by cavediver256

Ken, I don't think that is a moronic method at all.... At least with duct tape, you analyze the gas, write down your findings, with the date and time....A TANK MISSING DUCT TAPE???? ANALYZE IT AGAIN !!!!!! It seems to me, permanent MOD markings that you placed on a tank 2 or 3 years ago might get ya killed

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permanent markings will not kill anyone, no matter how old they are. of course the whole point of permanent markings is that those tanks have appropriate mix in them at all times; the whole point of permanent marking is that the gas within is also of "permanent" mix. period. I think the current incident, thinking you put air in a tank that actually had O2, is a good indication of the trouble you can get into by NOT using permanent markings and following through. No good to mark a tank DECO or OXYGEN 20, then putting air in it and noting it on tape that comes loose in travel or water! The permanent marking is not the problem here.

I've never trusted duct tape or sharpie on tank. I only know that was the mix or MOD at some unknown past time (unless date is included and maybe psi too). so if using nonmarked tanks that may have any mix in them it's best to add date it was last analyzed, psi it had at that time, and mix as well. I don't like marking them with percentage alone (or ppo2) - I am very comfortable knowing that my permanently marked tanks will always be filled with a mix that is good to the indicated MOD (e.g, 20, 70, 100, etc.). I always analyze prior to a dive to verify the mix is indeed acceptable to the indicated MOD, but I can't really see a downside to the permanent marking other than loss of ability to use that same tank for any mix, any MOD.

Whether one uses permanent markings or not, I think we can all agree that marking the MOD, and the Percentage of O2 (and He if trimix), AND analyzing at some point close to dive time to verify contents, is essential and proper gas management. Last year, Brandon died because the contents were not analyzed for CO and taught us all to pay attention to that gas as well. Now Carlos is gone due to a failure to analyze the mix for oxygen content! Brandon followed best practices and taught us a new best practice. Now another diver failed to follow well-established gas management recommendations in terms of knowing for sure what you are breathing and marking the tank accordingly and has got us all talking about what we think is best practice in tank markings and knowing your mix. An experienced cave and technical diver made a simple mistake and paid the ultimate price. Let's hope that his death spurs us all to reconsider and reevaluate our tank analysis and marking practices and thereby saves lives.

I first thought that "complacency" as a new guideline for cave divers was a crock - seemed like it was a catch-all that was covered already by the other guidelines. Now I'm not so sure. Perhaps it does deserve it's own place in the list.

skip

I have dedicated deco/stage cylinders for depths to 245'. All cylinders dedicated for below 130' have my name and MOD on the side of the cylinder and MOD with the mix on the neck permanently marked. From 130 and shallower, except oxygen, have my name and MOD permanently on the side and I use duct tape with a sharpie to put the MOD and mix on the neck as I will accept mixes that are a little off for shallower depths. All Oxygen is permanently dedicated for O2 and the cylinders are green so they can not be confused as anything other than O2.

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Originally Posted by mtherr

In an accident analysis thread, a participant made a point that permanent markings and not temporary markings should be used to identify scuba tank contents.

I believe this practice got kick started with the WKPP project and it proved to be a safe way (combined with operational procedures) to execute complex dives involving various travel, bottom and deco mixes.

Many people seem to have adopted this practice only partially. While diving at Ginnie and Peacock mostly in the last couple of years, I saw tanks with all sorts of MOD that made me believe they were not dedicated tanks. At Ginnie, in my last two trips, I noticed stages with MODs from 70 feet to 130. I rented myself a 100 foot tank that was not filled with EAN 34.

My practice when cave diving (single gas + o2) is to analyze all main, stage and deco bottles when the gear is setted up (on stages, I analyze when ready to install my regulator). On Caribbean dive trips, I analyze, mark and log analyses as per recreational standards.

Am I alone feeling that permanently marked tanks are not dedicated in real life?

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I apologize for still being in the "kiddie pool" end of cave diving.

But I ALWAYS use duct tape markings on my tanks.

1. I am usually using rental tanks when in Florida. What possible advantage is there in a "perment marking" over my OWN handwriting?
2. I prefer having the tank marked with the EXACT ppO2 mix in the tank after each fill.
3. The duct tape is in MY handwriting, with today's date. If it is NOT my writing, AND today's date- I don't breath it!
4. I have never had duct tape come off a tank or the (permenent marker) writing become smeared or unreadable.
5. I remove tape and remark the tank EVERY time it is filled.
6. I feel that there is LESS chance of error on my part, if I have a marking pen in hand while I am analizing the tank (as opposed to trying to fill the tank with the gas mix specified on the permenent marking).
7. I ALWAYS re-analize the gas mix on dive site to confirm that the duct tape marking is correct.
8. My opinion is that the concept of "permenent markings" began with the WKPP style mass dive operations where dozens to hundreds of tanks were in use, and not necessarily filled by each working diver himself (herself).

+1
Not everybody lives nears caves and has lots of tanks.
I'm not at all worried about duct tape coming off.

I use my black marker on rental tanks, and then remove it b4 returning them.

Why use any tape or sticker when you can write directly on the tank with indelible markers?

Duct/gaff tape is non-sense.

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Originally Posted by gianaameri

Duct/gaff tape is non-sense.

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Duct tape w/ Sharpie pen is fine, especially for tanks that see different PO2s. My dedicated 100% O2 has a decal.

Seriously, this duct tape/no duct tape argument is becoming as silly as some of the BM/SM arguments.

I mean...if you've GOT to slap some duct tape on it and write a MOD, do it.

I think the moral of the story here is to mark the MOD on your tanks and check the analysis. If you're going to be in town for a week and renting tanks, slap some tape on the bad boys, write the MOD, remove it when your done.

Taking a tank past its labeled MOD doesn't make any sense. Why bother even having a sticker on there?

I have found a tape I like better than duck tape for my labels. It is called hurricane tape and is made out of vinyl. It will take a permanent marker and not smear once dry. Plus it will peel off and not leave a residue on tank as the duck tape. Comes in rolls as duck tape and different colors. As a side note when I was teaching trimix I suggested to the student the second stage mouthpiece which was connected to there O2 bottle should be put into something like a Octo keeper. This makes the diver have to remove it before it can be used. Having tanks panted green, using a green hose or green second stage is fine if you can see it.


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Let's be clear, MOD markings are just that, a DEPTH marking. MOD markings can be permanent or temporary and devote that tank to an appropriate mix for the specified depth. MOD markings are large, usually 3" numbers, that can easily be seen by a diver AND his buddy during gas switches. MOD markings require no calculation underwater and tell a diver AND his buddy that a particular bottle can be used at any depth shallower than the MOD.

This is NOT the same as a gas analysis, which should be done prior to using any bottle. The gas is analyzed well in advance of the dive (usually at the dive shop) and the date, pressure, and contents are recorded. This should be written on either analysis tape or duct tape and placed near the neck of the tank. The analysis should be compared to the MOD markings prior to the dive and not relied on during the dive. Only the MOD marking needs to be referred to during the dive.

Skip, at home, I have 13 tanks and I agree with you, dedicated tanks are good. BUT I would never trust permanent markings on tanks that I do not own. Actually, I saw too many tanks for all sorts of MODs diving to believe that everyone is disciplined in dedicating specific mix to specific markings. I feel safe when analyzing the tank right there at the dive site when the rigging is already mounted. I am sure that there is no mistake. I also analyze my O2 bottle to make sure that this is the deco gas. Most of my Florida dives in the last 7 years are with rented tanks. I sometimes get tanks with MOD markings or deco tanks without markings... I only trust me and my analyzer. And if I have a long way to go, I also analyze at the dive shop prior to leaving. I believe that Duct tape is good too if it has my initials and if I was in control of the tank the whole time after it was filled. If the tank went in other's hands (like stopping a rental, returning it to the shop, letting someone else use it, etc.), the markings mine or not do not mean anything to me.

But back to my initial question... I am glad that some local divers have dozen of tanks and are well disciplined to manage their tanks... but is this rigorous enough that we could rely on permanent markings on any cylinder? I don't believe so... and I think permanent markings on tanks that are not self managed may not be helpful at all.

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Originally Posted by cavediver256

Ken, I don't think that is a moronic method at all.... At least with duct tape, you analyze the gas, write down your findings, with the date and time....A TANK MISSING DUCT TAPE???? ANALYZE IT AGAIN !!!!!! It seems to me, permanent MOD markings that you placed on a tank 2 or 3 years ago might get ya killed

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Same here after dive redo the tape. I also mark the tape when I check for CO. I only permanently my O2 bottles

Sure they are. When I went to Italy to dive, tanks had big ass MOD labels on the side, and I had my analysis sticker on the neck. Same as here in Florida. You still have to analyze your gas, even if the tank has a MOD sticker on it...

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Originally Posted by vicp

Duct tape w/ Sharpie pen is fine, especially for tanks that see different PO2s. My dedicated 100% O2 has a decal.

Seriously, this duct tape/no duct tape argument is becoming as silly as some of the BM/SM arguments.

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BM/SM does not kill (just two different styles).

Taking into account that all divers make mistakes, given the recent fatality, and others as well, we need to adopt a methodology which reduces the possibility of error.

The only way I see it is for the gas to be analysed by the diver himself every time the SCUBA tank leaves the garage/shop and for the MOD (i.e. gas switch depth) to be permanently marked by the diver on the tank (duct/gaff/any tape is not permanent).

At any rate that is what I do.

The moment the SCUBA tank goes back into the garage/shop, it needs to be analysed by the diver himself again when it thereafter goes out of the garage/shop and permanently marked by the diver again with the correct MOD.

Renting tanks changes everything. I have two tanks with bottom mix, four deco tanks. One for 20 feet, one for 70 feet, one for 100 feet and one for trimix deco. The 20, 70 and 100 are marked, the trimix deco is not. The bottom mix is not marked. For these I use duct tape. I also use duct tape on the deep deco tanks to provide a specific o2 percentage (not pp02), as in 35.3% on the 100-foot tank for example. This does not take a lot of discipline or a lot of tanks. I do partial pressure blending of nitrox and trimix at home, and whatever is available on the road (almost everywhere has pp blending, but 32% is also good for 100-foot tank). The 70-foot tank may have 45% or up to but no more than 50%. The actual percent is on duct tape. The point is that no matter the actual mix in a permanently marked tank, I know it's breathable at, but no more, than marked depth. Really, I don't see this takes any more discipline than any other aspect of cave or technical diving. you plan your dive and dive your plan, you mark your tanks, fill them as marked, and dive them as marked. I don't loan them, I do sometimes let others dive them, but I would never trust the contents if they were with another diver overnight or longer.

I can't imagine that a technical or cave diver would not have the tanks needed to do the planned dive, would not have analyzed the tanks just prior to the dive, no matter what markings are on it, or would rent tanks and not analyze them and mark accordingly. I don't think anyone is suggesting that. The notion of permanent markings on rental tanks is a rather off-point discussion. I too would not trust any tank, no matter the markings, that I did not personally fill and/or analyze and not merely analyze, but do so just prior to the dive no matter the temporary or permanent markings.

some buddies ask me why I'm analyzing a tank at the dive site, after I also analyzed it at the dive shop that filled it. My answer is that even I might have made a mistake earlier that same day. If I cannot get my analyzer to agree with the shop analyzer, I change the dive plan or cancel it until the discrepancy is explained and actual content determined.

Relying on permanent markings "on any cylinder" as you say is not wise. Relying on personal cylinders with permanent markings is also not wise. The real issue is analyzing every tank before every dive and marking it so you know and can verify what you are breathing during the dive. There are many ways to accomplish this. I like having permanently marked tanks and have no difficulty in making sure the content fits the permanent marking. I'm pretty sure my buddy also appreciates the 3" MOD numerals.

The current situation is a diver who "thought" he put air in a oxygen deco cylinder. The cylinder must have been marked for oxygen deco or it would not be called an oxygen deco cylinder or would have no markings at all - some cylinder that could have any percentage up to 100%. This is the problem at hand. marking cylinders for MOD and always analyzing to ensure it is the mix for that MOD, whether the markings are permanent or not, is the way to avoid this tragedy. not marking cylinders, not analyzing before the dive, relying on memory of what you thought you did at some time in the past, is not the way to avoid this tragedy.

I have learned that my memory is not as good as permanent markings on tanks. I have learned that I need reliable external supports to be safe (the tank marked 100 is always always always safe to 100 feet and no deeper). And I've learned that even with such external support I still need to double check contents by analyzing before every dive, no matter what my memory tells me. Memory is a liar, a seductress, a well-wishing hope, a voice in your head that leads you to mistaken assumptions. Memory is not trust-worthy.

skip

Lets face it, doesn't matter how you mark your tanks, or even if you mark them at all ..... Permanently, Duct Tape, tank color, regulator color, hose color or memorizing serial numbers for the appropriate tanks at depth.... when it comes to pulling a regulator off a tank, opening the valve, and taking a big old deep breath, IT IS YOUR ASS THAT IS GOING TO HAVE TO LIVE (OR DIE) with the decision you have just made!!!!!

Come on guys, do we have to beat this dead rotten smelly ass horse again?????

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Originally Posted by cavediver256

when it comes to pulling a regulator off a tank, opening the valve, and taking a big old deep breath, IT IS YOUR ASS THAT IS GOING TO HAVE TO LIVE (OR DIE) with the decision you have just made!!!!!

Come on guys, do we have to beat this dead rotten smelly ass horse again?????

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Amen brother

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Originally Posted by cavediver256

Lets face it, doesn't matter how you mark your tanks, or even if you mark them at all ..... Permanently, Duct Tape, tank color, regulator color, hose color or memorizing serial numbers for the appropriate tanks at depth.... when it comes to pulling a regulator off a tank, opening the valve, and taking a big old deep breath, IT IS YOUR ASS THAT IS GOING TO HAVE TO LIVE (OR DIE) with the decision you have just made!!!!!

Come on guys, do we have to beat this dead rotten smelly ass horse again?????

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Yes we do. And again and again for as long as any one cave diver forgets to do so and dies because of it. That death means we need to beat the horse again. and again. and again. until no one dies ever again from breathing the wrong mix and the wrong depth. when that happens we will then be free from beating the dead rotten smelly ass horse... until it happens we need to keep beating.

skip

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Originally Posted by skip

Yes we do. And again and again for as long as any one cave diver forgets to do so and dies because of it. That death means we need to beat the horse again. and again. and again. until no one dies ever again from breathing the wrong mix and the wrong depth. when that happens we will then be free from beating the dead rotten smelly ass horse... until it happens we need to keep beating.

skip

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Well Skip, just how are you going to prevent someone from doing something so irresponsible???? I am sure each and everyone here has heard this #### over and over again....from our training to threads just like this one, and YET someone else goes right out and does the same thing..... I am open to suggestions as to how you would prevent another tragedy. Should we make a few laws that prevent this, stop selling anything other than air and make it illegal to dive below 30ft ????? I believe that EVERYONE is responsible for his or her own decisions, and if you are irresponsible enough to breathe the wrong gas at the wrong depth in a cave, we shouldn't even call it a cave fatality, we should call it what it is.

We prevent it by education. Keeping in the front of people's minds. Its REAL easy to die from breathing the wrong gas, and it happens all the time. Clearly something isn't right, and people need reminding.

a feeling of quiet pleasure or security, often while unaware of some potential danger! This sure seems to come to mind.

I would never go so far as to say permenant markings will prevent deaths either. I remember a damn good diver expiring in 2011 who had permenant markings and it sure didn't help him but the above definition of complacency would have.

Duct tape, black mark, mailbox stickers, spray paint or pink fingernail polish will not make a difference if the diver does not read and/or analyze the contents.

It either piss poor training or plain not paying attention that kills. Oh and then there is foolish mistakes would would most likely derive from the other two or both.

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Originally Posted by PfcAJ

We prevent it by education. Keeping in the front of people's minds. Its REAL easy to die from breathing the wrong gas, and it happens all the time. Clearly something isn't right, and people need reminding.

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AJ, if people at this level of the game need to be reminded to analyze their gas and mark their tanks PROPERLY, should they be participating in this sport at all ?????

I'd like to say 'no, they shouldn't', but I also understand that people make mistakes. Everyone does. Understanding that people do and will continue to make mistakes reinforces the need to be vigilant and remind each other to slow down and go through the steps/process. Think, for a second, of how the last few 'wrong gas' fatalities happened. Not following the procedure. Something so simple, yet it has cost how many lives?

A 'screw it, let darwin sort it out' mentality is sloppy, intellectually lazy and gets us no where.

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Originally Posted by PfcAJ

.............intellectually lazy and gets us no where.

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Well I would think "intellecutally lazy" is the reason for this thread if nothing else........

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Originally Posted by PfcAJ

I'd like to say 'no, they shouldn't', but I also understand that people make mistakes. Everyone does. Understanding that people do and will continue to make mistakes reinforces the need to be vigilant and remind each other to slow down and go through the steps/process. Think, for a second, of how the last few 'wrong gas' fatalities happened. Not following the procedure. Something so simple, yet it has cost how many lives?

A 'screw it, let darwin sort it out' mentality is sloppy, intellectually lazy and gets us no where.

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You are right,the human factor is huge. Testing gas,marking tanks,and in water verifying that you have the correct tank are all essential,but somehow this slips by us and the results are costly. It really sucks that accidents make us more vigilent in something that there should never be a shortcut. Maybe the buddy system needs to be extended to testing each other's tanks to verify things? I know some guides who will test the person they are taking tanks,maybe it is worthwhile to save the sad job of pulling a buddies body out of the cave.

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Originally Posted by mtherr

But back to my initial question... I am glad that some local divers have dozen of tanks and are well disciplined to manage their tanks... but is this rigorous enough that we could rely on permanent markings on any cylinder? I don't believe so... and I think permanent markings on tanks that are not self managed may not be helpful at all.

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I'm not sure I understand what you mean by "manage their tanks." The entire point of MOD markings is to rely on them and them only in the water. The analysis before the dive verifies that the contents match the MOD markings and that it can be relied on. That's the system. It makes no difference whether they are your tanks or not.

I guess I'm the only one who also labels his second stages. All bailout cylinders have small tags at the second stage as well as the QD with the mix. I try to position them so they stick up right in front of my eyes and I see the mix before I stick it in my mouth. Yes, it has the potential to be mislabeled, but that's why I am meticulous about it.

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Originally Posted by skip

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I can't imagine that a technical or cave diver would not have the tanks needed to do the planned dive, would not have analyzed the tanks just prior to the dive, no matter what markings are on it, or would rent tanks and not analyze them and mark accordingly.

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Then you have no imagination.

Hi all,

I think it is a great thing, that we all try to make diving safer and discuss these accidents in order to learn from them.

I dont believe that this is solely to do with cylinder markings though.
I am in general a firm believer of dedicated tanks - and i do have fixed MOD's on all my deco and stage cylinders ( MOD stickers at the sides near the bottom and permanent markers 4 times around the cylinder neck ) but this is just how I do it - I think there are many ways that would work, and when I travel I am perfectly happy using differnt methods. One thing i would never skip is my personal analyses marking at the neck of the tank! a peace of duct tape with the date of the analyses, the exact content and MY signature. If a tank for some reason dont have this information, i dont breath it!

But what is even more important than the cylinder markings ( as long as they are marked ) is the switching procedure! and that our buddy confirms the switch! I know a lot of us says, of cause! we always do this - but it would have saved Jim and probably also the Ginnie accident, and most other switching accidents!.

What I learned from this accident ( the way i think it happened ) is that this could just as well have happened to me! I am extremely anal about switches under water, really check and re-check switches. make the entire team check EVERY single cylinder drop - is it the right cylinder? is is closed ? so you know what your team mate is breathing and have on him at every single point of the dive.

BUT I can imagine not being as anal about the starting stage, we are all good divers, in a place with multiple tanks and scooters - and we are on the surface! who makes a mistake here ? sure we check and make sure, but not as through as at the other stages at the dive - i guess we dont expect an error on this stage of the dive, we are eager to get going, and truth be told often it is pretty uncomftable being to long on the surface with tons of cylinders and multiple scooters, so everybody is fairly eager to hit the trigger, and our procedures are made in a world of no gravity! some of them are pretty hard to do at the surface.

But imagine - you are a good diver!, you are going to do whatever major dive, maybe even an exploration dive.
You are at the surface, loaded with gear laughing with your team joking of how much line you are going to add, and you know - that it requires all your focus to get to the end of line with enough gas to actually explore for a while. your focus is at the goal not on the travel there.
you pull the wrong reg from the stack of cylinders, but it is hard to see from pile of cylinders under your arm, and you just managed to clip everything on - it is 40 deg and you are a bit warm.
you yell at your buddy to see if he is ready, and with a laugh he gives you the 1-2-3- GOGOGO and you hit the trigger !and you never look back before you tox

this shouldent happen! we all know that it should not, and that we should have caught it ourself and our buddy should have caught it - but i could so see the scenario happen.

The dive starts and ends at the surface! I for now will be way more anal about my "surface switch" from now on - this is a dangerous one, as I am actually carrying oxygen during this switch!

ok and I have now learned that this has nothing to do with the current devils cave accident, I am sorry for speculation! and acting without correct information :( the rest of my post i think still makes sense though :-)

I started this thread after reading a comment to the effect that permament marking was important and temporary markings were a bad practice. My reaction to this comment was negative because I am pretty sure that permament markings are not universally respected. This thread has nothing to do with the Accident analysis discussion.

I understand that some participants really dedicate tanks for mixes and this is good. I did the same way before it became a practice to mark tanks with numbers (I used -- in mid 90's -- to have a Yellow tank with yellow face Jetstream for EAN 32 deco mix, Red tank with black Jetstream for EAN 50 deco mix and green O2 marked with green hose and green taped Sherwood second stage for O2). My back gas was accessed with Scubapro regs. I would never mix these things up when I was doing that.

However, this works when you have your own stuff, you controll it and others are not using it. This practice was also capital in ensuring safety for the WKPP project, I am sure.

But as a user of temporary tanks while travelling, permament markings have no meaning to me. I rely to in shop and on site analyzes. Temporary markings are used to make sure I dive with the tanks I analyzed on Carabean trips. While I used to do more complex dives when I was younger, my dives now are pretty much all single-mix nitrox dives with O2 decompression.

Thanks all for partiipating and I would like more discussion around how to ensure proper permanent marking or how to disable it if not reliable (for example, should I put a cover on marked tanks when I rent a tank while travelling)?

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Originally Posted by mtherr

I started this thread after reading a comment to the effect that permament marking was important and temporary markings were a bad practice. My reaction to this comment was negative because I am pretty sure that permament markings are not universally respected. This thread has nothing to do with the Accident analysis discussion.

I understand that some participants really dedicate tanks for mixes and this is good. I did the same way before it became a practice to mark tanks with numbers (I used -- in mid 90's -- to have a Yellow tank with yellow face Jetstream for EAN 32 deco mix, Red tank with black Jetstream for EAN 50 deco mix and green O2 marked with green hose and green taped Sherwood second stage for O2). My back gas was accessed with Scubapro regs. I would never mix these things up when I was doing that.

However, this works when you have your own stuff, you controll it and others are not using it. This practice was also capital in ensuring safety for the WKPP project, I am sure.

But as a user of temporary tanks while travelling, permament markings have no meaning to me. I rely to in shop and on site analyzes. Temporary markings are used to make sure I dive with the tanks I analyzed on Carabean trips. While I used to do more complex dives when I was younger, my dives now are pretty much all single-mix nitrox dives with O2 decompression.

Thanks all for partiipating and I would like more discussion around how to ensure proper permanent marking or how to disable it if not reliable (for example, should I put a cover on marked tanks when I rent a tank while travelling)?

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Allow me to help then.

WKPP (and DIR, GUE, TDI, IANTD, IART... apologies if I forgot to include the rest) got it wrong.

SCUBA cylinders, rentals or personal, should bear no gas markings and no stickers whatsoever to start.

The diver analyses the gas and with a permanent marker places on the tank neck his name and the MOD (meaning the diver chosen gas switch depth) of the gas mix.

So, for example, Carlos (a hypothetical diver) buys a new Alu80 cylinder and then he fills it with O2.

He then analyses and writes on the neck with a black permanent marker "Carlos" and "6M" (or "10F" if feet he uses as unit of measurement).

Weeks later he decides to use Air instead of O2.

He takes his Alu80 tank and wipes off with a bit of solvent the "6M" and empties the tank and fills it with Air.

Then Carlos analyses his tank to confirm it contains Air and marks it "66M" (the name "Carlos" is still there, so no change there).

When Carlos returns from his dive - having breathed Air and not O2 - he stores his tanks in the garage.

Next time Carlos picks the tank up, he repeats the process and before the Alu80 leaves the garage he makes sure the tank is analysed and the correct MOD is permanently placed on the tank neck.

Unfortunately, somebody a long time ago decided to do it differently, and then somebody else decided to do it a little more differently as well, and where we are now is tanks with far too much information and stickers of all kinds when all we need on the tank is 2 pieces of information: name and MOD.

Quote:

---

Originally Posted by gianaameri

Allow me to help then.

WKPP (and DIR, GUE, TDI, IANTD, IART... apologies if I forgot to include the rest) got it wrong.

SCUBA cylinders, rentals or personal, should bear no gas markings and no stickers whatsoever to start.

The diver analyses the gas and with a permanent marker places on the tank neck his name and the MOD (meaning the diver chosen gas switch depth) of the gas mix.

So, for example, Carlos (a hypothetical diver) buys a new Alu80 cylinder and then he fills it with O2.

He then analyses and writes on the neck with a black permanent marker "Carlos" and "6M" (or "10F" if feet he uses as unit of measurement).

Weeks later he decides to use Air instead of O2.

He takes his Alu80 tank and wipes off with a bit of solvent the "6M" and empties the tank and fills it with Air.

Then Carlos analyses his tank to confirm it contains Air and marks it "66M" (the name "Carlos" is still there, so no change there).

When Carlos returns from his dive - having breathed Air and not O2 - he stores his tanks in the garage.

Next time Carlos picks the tank up, he repeats the process and before the Alu80 leaves the garage he makes sure the tank is analysed and the correct MOD is permanently placed on the tank neck.

Unfortunately, somebody a long time ago decided to do it differently, and then somebody else decided to do it a little more differently as well, and where we are now is tanks with far too much information and stickers of all kinds when all we need on the tank is 2 pieces of information: name and MOD.

---

Mod stickers also tell the tank monkey what mix should be in there. Not to mention their obvious use of showing a buddy what you are breathing (which worked in Carlos' case, but was ignored).

I have no issue using tape to cover the 9 and writing a big fat 5 in it if I'm going to Indian and putting 150 gas in a 190 bottle. Just whatever you do, fix or cover the mod before filling.

When you get filled, tape the valve off after analysis. If there's no tape, recheck your gas.

Quote:

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Originally Posted by jj1987

Mod stickers also tell the tank monkey what mix should be in there. Not to mention their obvious use of showing a buddy what you are breathing (which worked in Carlos' case, but was ignored).

I have no issue using tape to cover the 9 and writing a big fat 5 in it if I'm going to Indian and putting 150 gas in a 190 bottle. Just whatever you do, fix or cover the mod before filling.

When you get filled, tape the valve off after analysis. If there's no tape, recheck your gas.

---

I put the analyser at the base of the tank if the tank needs analysing, so when I pick the tank up I can see the analyser and remember to use it.

I do not agree though on the "theories" (i.e. DIR...) whereby the onus is placed on the buddy to verify the gas the other diver is using.

The decision to dive is of one person only - the diver.

The stuff which goes in the mouth is for one person to decide and put it in the mouth - the diver.

If my buddy breathes O2 instead of 12/88 - he made a mistake and it has got nothing to do with me. Same if I were to make that mistake - it is my responsibility to make sure that what I put in my mouth is good for me.

So, in the case of Carlos (the hypothetical diver I made up in this thread), if he is my buddy and puts in his mouth an O2 reg instead of an Air reg - his mistake and no moral responsibility on my part. I have to worry already about what reg I am putting in my mouth, that I should not have the additional task loading to check/baby-sit everybody else.

Now, I see all the times people strapping on 3 tanks and putting behind and around their neck 3 hose and 3 regulators and I wonder - how the hell this guy does not make a mistake and take the wrong reg? (if he does, his problem for sure).

So, what I do, because I make all sorts of mistakes, like forgetting to put my fins ON and start the dive with no fins (fully loaded with 4 tanks, a rebreather, a scooter, and a back-up scooter...), I put a woman's short nylon sock on the O2 2nd stage.

It protects it, and if I put the O2 reg in my mouth by mistake it will feel "different."

For the record, the onus is not on the buddy in the DIR system. We're all grown ups, and its the divers responsibility to know why he or she is breathing. The buddy check is an additional layer. A verification. It is not the sole method.

Looking at the MOD sticker before you put the reg in your mouth is the only sure fire way. Matching gas to MOD is done pre-dive, on the surface, at the fill station. A tank doesn't leave till it has been analyzed and the analysis matches the MOD, and a tank doesn't get a reg without a current analysis sticker. Period. Colored regs, MOD tags on hoses, all go right out the window the second you need to borrow something. The MOD sticker is the only fixed thing in the entire equation.

Quote:

---

Originally Posted by gianaameri

I put the analyser at the base of the tank if the tank needs analysing, so when I pick the tank up I can see the analyser and remember to use it.

I do not agree though on the "theories" (i.e. DIR...) whereby the onus is placed on the buddy to verify the gas the other diver is using.

The decision to dive is of one person only - the diver.

The stuff which goes in the mouth is for one person to decide and put it in the mouth - the diver.

If my buddy breathes O2 instead of 12/88 - he made a mistake and it has got nothing to do with me. Same if I were to make that mistake - it is my responsibility to make sure that what I put in my mouth is good for me.

So, in the case of Carlos (the hypothetical diver I made up in this thread), if he is my buddy and puts in his mouth an O2 reg instead of an Air reg - his mistake and no moral responsibility on my part. I have to worry already about what reg I am putting in my mouth, that I should not have the additional task loading to check/baby-sit everybody else.

Now, I see all the times people strapping on 3 tanks and putting behind and around their neck 3 hose and 3 regulators and I wonder - how the hell this guy does not make a mistake and take the wrong reg? (if he does, his problem for sure).

So, what I do, because I make all sorts of mistakes, like forgetting to put my fins ON and start the dive with no fins (fully loaded with 4 tanks, a rebreather, a scooter, and a back-up scooter...), I put a woman's short nylon sock on the O2 2nd stage.

It protects it, and if I put the O2 reg in my mouth by mistake it will feel "different."

---

Wow, I didn't know this mentality still existed

Quote:

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Originally Posted by tursiops

+1
Not everybody lives nears caves and has lots of tanks.
I'm not at all worried about duct tape coming off.

---

I have never had duct tape come off by itself. I definitely have a finite number of cylinders.

Quote:

---

Originally Posted by Pavão

Wow, I didn't know this mentality still existed

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Which part of this do you agree or disagree with? I don't think I'm quite as far as "everyone for themselves" but I also don't analyze my buddies tanks... I let him do that.

Quote:

---

Originally Posted by bletso

I have never had duct tape come off by itself. I definitely have a finite number of cylinders.

---

i have
it doesn't stick to shot blasted tanks

Quote:

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Originally Posted by LiteHedded

i have
it doesn't stick to shot blasted tanks

---

or in tannic water

I am in the old school pool.

My only O2 tanks are two al 40's marked O2, are only used for pure O2, and have either a specific sherwood or OMS reg on them.

Deco tanks from 130' up are not permanently marked but have current lablel and mix and only use a dacor reversible second stage on them with sherwood O2 cleaned first stages that can be used on the O2 tank in an emergency. (The switch would be made UW only if necessary. In other words I would not start a dive with the same type of reg on my O2 and 130 or less bottle)

Stage tanks are labeled with current mix and only get an apex stage reg.

Back (or side) gas is labeled current mix and only get my primary use regs on them.

I have enough tanks and regs such that on my worse day I know what reg is in my hand. Could I still screw it up? Of course I could.

Quote:

---

Originally Posted by mer

or in tannic water

---

or on any tank.

It sticks, but then it can come off, and it does come off (if you are a cave diver and actually cave dive).

The only way to make it permanent is to take more than a full turn around the tank so that the Duct/Gall tape sticks on itself and is tight around the tank...

BUT y'a all missing the point:

What is the point to use Duct/Gall tape if you can write with a black permanent marker on the tank itself?

Are people afraid the tank gets hurt if you write on it directly?

Somebody had the not so bright idea to use Duct/Gall tape once upon a time and nobody has since then asked "Why? What is the point?"

Quote:

---

Originally Posted by gianaameri

or on any tank.

It sticks, but then it can come off, and it does come off (if you are a cave diver and actually cave dive).

The only way to make it permanent is to take more than a full turn around the tank so that the Duct/Gall tape sticks on itself and is tight around the tank...

BUT y'a all missing the point:

What is the point to use Duct/Gall tape if you can write with a black permanent marker on the tank itself?

Are people afraid the tank gets hurt if you write on it directly?

Somebody had the not so bright idea to use Duct/Gall tape once upon a time and nobody has since then asked "Why? What is the point?"

---

You lost me there...

Write on the tank? My luxfer would never forgive me

Quote:

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Originally Posted by Garth

You lost me there...

Write on the tank? My luxfer would never forgive me

---

Take a frigging black permanent marker and write on the tank.

Give me a couple of moms. and will post some pics.

Quote:

---

Originally Posted by gianaameri

Take a frigging black permanent marker and write on the tank.

Give me a couple of moms. and will post some pics.

---

Here ya go:

http://www.rebreathermallorca.com/vi...pmtanksafe.jpg

Ducttape and a wide tip marker works for me. I do too many different styles of diving to permanently mark a tank with MOD.
My tanks are all permanently marked with my name and my own tank numbers (inventory control), but my MOD may change depending on the dive I do.

I analyze and mark all content on my tanks before leaving the dive shop as well. This way they have a chance to fix it before I leave if something is not right.

Quote:

---

Originally Posted by gianaameri

Here ya go:

---

I think you're on to something here, particularly for traveling divers, but would suggest larger numbers and placement so that your buddy can easily see them at gas switches.

Quote:

---

Originally Posted by jcr

I think you're on to something here, particularly for traveling divers, but would suggest larger numbers and placement so that your buddy can easily see them at gas switches.

---

I used to have large number DIR style stickers on the side of the tank (still got a box of them). Eventually, they get destroyed in a cave environment, so I stopped putting them back on.

If people feel like they need a buddy to confirm their gas, I guess they can paint bigger numbers with the permanent marker wherever they want.

Still, stickers or big numbers on the side of the tank in a cave will need refreshing.

This was my bail-out tank on an early wreck expedition (72 is in meters):

https://sphotos-a-ams.xx.fbcdn.net/h...454_8733_n.jpg

A fellow diver in a separate post asked for "proof" that Duct Tape falls off tanks. Not sure if he was making a joke or was serious, but all who cave dive know that Duct Tape is not a permanent marking and it comes off and it can and does fall off in a cave environment - be that during transport or during the dive. The only exception is if you wrap it tight and on itself all around the tank (but what is the point of writing on Duct Tape when one can write directly on the tank with a black permanent marker???)

As "proof" (in case he was serious) I put forward the permanent markings made from cave diving on my O2 rebreather tanks and side-mount tanks. The cave has taken the paint off (you can imagine what happens to a silly piece of Duct Tape after carrying tanks up and down the dry-section of a real cave - not a tourist one - and actually using it cave diving... real cave have restrictions too!).

Other divers raised the issue about tanks being stolen at Ginnie by drunk divers. I had my tank stolen once, and since then I permanently mark the bottom with whatever spare can of spray paint I can get my hands on when a bit of re-painting is due (the color from the last can is so ugly I really do not think anybody will want to steal my tanks... rebreather tanks and rebreather cannister bottom section also regularly anti-theft spray marked/painted).

http://www.rebreathermallorca.com/video/safety/tan1.jpg
http://www.rebreathermallorca.com/video/safety/tan2.jpg
http://www.rebreathermallorca.com/video/safety/tan3.jpg
http://www.rebreathermallorca.com/video/safety/tan4.jpg
http://www.rebreathermallorca.com/video/safety/tan5.jpg
http://www.rebreathermallorca.com/video/safety/tan6.jpg

Your whole anti-duct tape theme is killing me. Yes, duct tape comes off. That is the point for me, and pretty much everyone I dive with. It does not simply fall off in the course of our dive. It is removed after EVERY dive. We place it on the neck of our tanks and write the mix as analyzed, the date, and our initials. We do this at the fill station. When we get to the dive site we verify the markings again to make sure that we grab the correct tank that we just analyzed. If need be, we re-analyze the tank and place a new piece of tape on the tank. It is not meant to be permanent. That is what the big ass MOD sticker on the side of our DEDICATED tanks is for!

I am not saying your way is wrong, or going to get you killed. However, you seem to have an over zealous zeal and hard on for assuming what we are doing is wrong. Yet, you can point out no truly logical flaw in our method. Well except for saying someone died doing it. Well that someone failed to follow those rules. The rules were not broken, they were simply not followed.

I still use the large DIR type sticky back labels, 70 ft, 100 ft, etc. I then also use painters tape (comes off easily with no residue) to mark psi and mix %'s. The psi and mix%'s are for me, the large permanent markings are for my buddy to verify. I also have the DIR labels at the top of the tank around the neck where I can look down and see the MOD. I follow the hose from second stage (with my hand) to the tank and my hand ends up right at the MOD markings. But I also have dedicated stage and deep deco tanks and do not ever put gas in them that would violate the MOD. I may have different mixes, but none that violate the MOD (the 70 ft tank may be EAN50, or it may be 50/25, or 25/25, for example). The painters tape tells me the mix and is put on at the fill station, where I analyze the gas. The tanks are then analyzed again pre-dive on site to verify the marking or to replace the tape if it came off in transport. At that time I write it in my wet notes with the dive plan (and contingencies) and program the percentages into my computers.

If the tape comes off during the dive, who cares? I usually remove it before the dive anyway. At this point the exact %;s are in my computers, and on my wet notes, and the MOD is there for me and buddy to see and verify during the dive.

I could write the percentages on the tank with a sharpie, and have when no tape available. It is easily "erased" by scribbling fresh sharpie ink all over it and rubbing with paper towel (or a thumb). It says it's permanent and it is until you scribble fresh sharpie ink over it and rub it off before the ink dries. Personally, I prefer the DIR MOD labels on the neck because it is so much easier to read (black numerals on white background that shines when a light is put on it), especially when it's dark silty water.

skip

Quote:

---

Originally Posted by JamesK

Your whole anti-duct tape theme is killing me. Yes, duct tape comes off. That is the point for me, and pretty much everyone I dive with. It does not simply fall off in the course of our dive. It is removed after EVERY dive. We place it on the neck of our tanks and write the mix as analyzed, the date, and our initials. We do this at the fill station. When we get to the dive site we verify the markings again to make sure that we grab the correct tank that we just analyzed. If need be, we re-analyze the tank and place a new piece of tape on the tank. It is not meant to be permanent. That is what the big ass MOD sticker on the side of our DEDICATED tanks is for!

I am not saying your way is wrong, or going to get you killed. However, you seem to have an over zealous zeal and hard on for assuming what we are doing is wrong. Yet, you can point out no truly logical flaw in our method. Well except for saying someone died doing it. Well that someone failed to follow those rules. The rules were not broken, they were simply not followed.

---

Carl Spencer died in the Fatal Brittanic expeditions following the rules you set out.

A "Team" dive to that level of expertise and professionalism allowed for a mismarked tank to actually make it into the water and kill a Team member.

The system you describe in your post is weak because a single diver error creates a failure point for the whole Team.

You end up with a dead body to recover (the diver who breathed the mismarked tank). Dead body recovery (or near dead recovery) is fraught with risk, not to mention in a cave environment that the dead body can be the cork in the bottle which blocks your only exit).

A system which uses only permanent tank markings is more solid than a system which uses temporary markings (in part or in whole).

I use painters tape to mark the analyzed mix. They have lasted several "rough" dives with no problem. It's all about placement (around the neck). They come off easy when I desire them to change, so I use them all the time.

Works for me, maybe not for you. So long as the tank is properly marked, who cares how it's done?

Quote:

---

Originally Posted by gianaameri

Carl Spencer died in the Fatal Brittanic expeditions following the rules you set out.

A "Team" dive to that level of expertise and professionalism allowed for a mismarked tank to actually make it into the water and kill a Team member.

The system you describe in your post is weak because a single diver error creates a failure point for the whole Team.

You end up with a dead body to recover (the diver who breathed the mismarked tank). Dead body recovery (or near dead recovery) is fraught with risk, not to mention in a cave environment that the dead body can be the cork in the bottle which blocks your only exit).

A system which uses only permanent tank markings is more solid than a system which uses temporary markings (in part or in whole).

---

OMFG! Do you read and comprehend what everyone, including yourself is saying? How are my tanks NOT permanently marked? It ALWAYS has the MOD in BIG ASS numbers on the side of the tank. The tank NEVER gets filled with anything that violates that MOD. In fact, I would state that your permanent marker way, is by your own admission, a temporary way of marking a tank. You yourself state that if you want to put a different gas in the tank, you simply erase the markings and change them. I never change my MOD stickers because I don't put a different gas in them. You can not seem to get that through your head.

I understand what you are saying about a mistake by me, well multiple mistakes by me, could jeopardize the team. However, that has absolutely NOTHING to do with the marking of the tanks. That has to do with the the failure to properly follow established rules. So, if group analysis is the answer, then marking the tanks your way or mine, will not make one juicy tasty little morsel of a difference in the outcome.

Quote:

---

Originally Posted by Tegg

So long as the tank is properly marked, who cares how it's done?

---

If it is "permanent" - any system is fine.

Sticky tape is never permanent.

I'll post some pictures of my bail-out tanks when I get them back from the cave (now in safe storage in the cave awaiting for the next dive).

I stage them and leave them staged underwater for up to 10 days of cave diving.

The haloclyne is so corrosive that it strips the paint off and it will eat into the metal if left long enough.

The cave was originally marked with directional arrows by Martin Farr - made of aluminum.

All such directional "old style" arrows are gone. Eaten up by the cave.

What works works, but it has to be permanent, and it all depends also on the diving you do.

I prefer a system which works all the times in all environments including when I leave my tanks unattended and some drunk or idiot or wanderer has come across my tanks (no sticky label, nothing he can mess up with).

Quote:

---

Originally Posted by JamesK

So, if group analysis is the answer, then marking the tanks your way or mine, will not make one juicy tasty little morsel of a difference in the outcome.

---

If your MOD marking is permanent, it is fine.

Why do you want to add to it a piece of Duct Tape with information you believe to be relevant which can come off and/or be source of confusion?

Quote:

---

Originally Posted by gianaameri

If it is "permanent" - any system is fine.

Sticky tape is never permanent.

I'll post some pictures of my bail-out tanks when I get them back from the cave (now in safe storage in the cave awaiting for the next dive).

I stage them and leave them staged underwater for up to 10 days of cave diving.

The haloclyne is so corrosive that it strips the paint off and it will eat into the metal if left long enough.

The cave was originally marked with directional arrows by Martin Farr - made of aluminum.

All such directional "old style" arrows are gone. Eaten up by the cave.

What works works, but it has to be permanent, and it all depends also on the diving you do.

I prefer a system which works all the times in all environments including when I leave my tanks unattended and some drunk or idiot or wanderer has come across my tanks (no sticky label, nothing he can mess up with).

---

Like I said... if you dive in acid water and leave the tanks there for extreme amounts of time, then modification for how you mark tanks is needed. If one is carrying a tank into a cave and not leaving it there for extended periods of time, then the method I use would work fine.

Either way, people should do what works for them in the environment that they dive. Pretty simple.

BTW, I have left my tanks in water both salt and fresh for long times and found that my painters tape held just fine. (several days)

Quote:

---

Originally Posted by gianaameri

If your MOD marking is permanent, it is fine.

Why do you want to add to it a piece of Duct Tape with information you believe to be relevant which can come off and/or be source of confusion?

---

I don't add the MOD to the duct tape. I add the the actual mix percent, the date I analyze it, and my initials. This is done as a verification that tank has been properly analyzed and when it was last analyzed.

Quote:

---

Originally Posted by gianaameri

If your MOD marking is permanent, it is fine.

Why do you want to add to it a piece of Duct Tape with information you believe to be relevant which can come off and/or be source of confusion?

---

For stage cylinders below 130 feet the MOD is on the side and the neck of the cylinder. For 130 and shallower I use duct tape on the neck which I explained in an earlier post. Another reason for the permanent marking for the deeper stages is that the ascent rate is fast and the stop time short and critical. Shallower the ascent is slower and an extra minute or two to pull a cylinder to check MOD if the neck marking was missing is not an issue. With stages below my SM cylinders I can see the neck by pulling the cylinder down a bit. With top mounted stages I need to pull the top clip to get them out enough to see the neck. For top or bottom I can't see the side of the cylinder without pulling both clips and moving the cylinder in front of me.

If I am mixing 32/whatever for 130 feet and it comes out to be 29/whatever I will go with that mix however I want to know what the percentage came out as and plan the schedule accordingly. Anything deeper than 130 feet and it comes out on the numbers or I will remix until it is right.

This is just how I do it and feel comfortable with the system. Exactly how cylinders are marked is not what I believe to be the main problem. Taking a cylinder marked for a shallower MOD than it is planned to be used is one of them. Not analyzing any cylinder to confirm the mix before the dive is another. Agreeing to dive with a teammate that has done either or both of the first two is a third critical error. I have enough cylinders that some of them may not be used for over a year or so. Even with the MOD markings and analysis on them I would recheck both pressure and mix before using any of them.

One last thing that we now always do it check everything for CO. That is something that should be added to everyone's procedures IMHO.

Quote:

---

Originally Posted by JamesK

I don't add the MOD to the duct tape. I add the the actual mix percent, the date I analyze it, and my initials. This is done as a verification that tank has been properly analyzed and when it was last analyzed.

---

Then you store it till you next use it and you and your Team/Buddy go diving without re-analysing that tank?

Quote:

---

Originally Posted by Bobby

One last thing that we now always do it check everything for CO. That is something that should be added to everyone's procedures IMHO.

---

You should consider checking for CO2 as well because the better and proper filtering systems would convert any CO from the compressor into CO2.

So, depending on the filtering system, and if you have one of the better ones, if your compressor produces CO, you will find no CO in the tank, but excess CO2 (above 0.03 - 0.05%).

Quote:

---

Originally Posted by gianaameri

If your MOD marking is permanent, it is fine.

Why do you want to add to it a piece of Duct Tape with information you believe to be relevant which can come off and/or be source of confusion?

---

Quote:

---

Originally Posted by JamesK

I don't add the MOD to the duct tape. I add the the actual mix percent, the date I analyze it, and my initials. This is done as a verification that tank has been properly analyzed and when it was last analyzed.

---

Hopefully he finally understood what everyone is telling him. ;)

Quote:

---

Originally Posted by gianaameri

Then you store it till you next use it and you and your Team/Buddy go diving without re-analysing that tank?

---

No. I do not store full tanks. I get my fills the morning of the dive 90% of the time. If I do it before hand, they get re-analyzed before the regs go on as I am gearing up for the dive. However, having the tape there shows the days the fills were done.


Sent from my iPhone using Tapatalk 2

Quote:

---

Originally Posted by gianaameri

Then you store it till you next use it and you and your Team/Buddy go diving without re-analysing that tank?

---

Negative. Analyze it again.

My usual routine is to analyze it, date it, and it if doesn't get used with a day or two of the analysis (date is marked on the tape), it gets re-analyzed.

Me, tanks get analyzed right before I dove the at the site or before assembling my kit at the dock. I do this regardless of when I filled the (that morning, last week, whatever) the old analysis label comes off and a new one is attached.
All deco tanks have permanent MOD stickers. And everything has my name sticker on it.

Quote:

---

Originally Posted by gianaameri

If it is "permanent" - any system is fine.

Sticky tape is never permanent.

---

A couple years ago, I rented two 40 cuft oxygen tanks from a dive shop in cave country. In addition to all the usual permanent markings, I added a couple duct tape labels to the tanks. I marked one tank "MEDICAL" and the other tank "DECO" so that I was keeping one tank in reserve for medical emergency only.

I had intended to remove my duct tape when I returned the tanks, but I obviously forgot. Because a year later, when I went back to rent two O2 tanks again... there were my two tanks, still marked "MEDICAL" and "DECO", in my handwriting.

I have never had tape accidentally peel off a tank, and any tape that survives a YEAR in cave country rental service is "permanent" enough for me.

Quote:

---

Originally Posted by gschaut

I have never had tape accidentally peel off a tank, and any tape that survives a YEAR in cave country rental service is "permanent" enough for me.

---

The duct tape we use around here (European "TESA" brand) is so durable, a lot of folks use it to protect the bottom of their (bootless) doubles against damage of placing them on the ground.
There is absolutely no way these labels will ever come off on their own. Also they are white, which is perfect contrast for black lettering. What might (and probably will) rub off is the sharpie labeling, which is a good thing, since it forces us to re-analyze and re-label.

Quote:

---

Originally Posted by nakatomi

The duct tape we use around here (European "TESA" brand) is so durable, a lot of folks use it to protect the bottom of their (bootless) doubles against damage of placing them on the ground.
There is absolutely no way these labels will ever come off on their own. Also they are white, which is perfect contrast for black lettering. What might (and probably will) rub off is the sharpie labeling, which is a good thing, since it forces us to re-analyze and re-label.

---

Some buddies from Holland I dived with last year had carbon fiber tanks and put Duct Tape all around them to protect them in the cave.

Duct Tape stuck on itself and run around tight the whole tank does not come off (for Duct Tape lovers).

Carbon fiber tanks, really? I've only used the in aircraft for O2 bottles. Just threw two away as a matter of fact, you don't hydro those, when they expire, they go in the trash. Bet they were buoyant as the devil too, how did they sink them, wrap the tank around several pieces of lead?

Quote:

---

Originally Posted by gianaameri

You should consider checking for CO2 as well because the better and proper filtering systems would convert any CO from the compressor into CO2.

So, depending on the filtering system, and if you have one of the better ones, if your compressor produces CO, you will find no CO in the tank, but excess CO2 (above 0.03 - 0.05%).

---

Dude, you work so hard in an attempt to prove superior intellect and you accomplish the exact opposite.

Quote:

---

Originally Posted by a64pilot

Carbon fiber tanks, really? I've only used the in aircraft for O2 bottles. Just threw two away as a matter of fact, you don't hydro those, when they expire, they go in the trash. Bet they were buoyant as the devil too, how did they sink them, wrap the tank around several pieces of lead?

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Many people use them on their rebreathers, especially rEvo folks. Why not pose your question in the relevant forum?

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Originally Posted by a64pilot

Carbon fiber tanks, really? I've only used the in aircraft for O2 bottles. Just threw two away as a matter of fact, you don't hydro those, when they expire, they go in the trash. Bet they were buoyant as the devil too, how did they sink them, wrap the tank around several pieces of lead?

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Yes, they were backmounted double carbon fiber tanks (not for rebreathers) and the diver split them in two separate side-mounts because a. his isolator valve leaked, and b. they were easier to carry up and down and in and out the caves we were diving.

He had them wrapped in Duct Tape to protect them.

I did not pay attention to how much lead he was using, so I have no idea. He had some fine dives with them no problem (other than for the silly isolator configuration).

I think he was using a wet-suit (almost 100% sure he had no dry-suit off the top of my head).

He had the carbon fiber tanks wrapped in Duct Tape because they'd get destroyed in the cave otherwise.

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Originally Posted by a64pilot

Carbon fiber tanks, really? I've only used the in aircraft for O2 bottles. Just threw two away as a matter of fact, you don't hydro those, when they expire, they go in the trash. Bet they were buoyant as the devil too, how did they sink them, wrap the tank around several pieces of lead?

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Most Fire Dept SCBA tanks are carbon fiber. But FD uses them because they are light, in water they would have to be VERY buoyant. FD service hydro's carbon fiber tanks every 3 years, and trashes them after 15 years of service.

I remember my teacher telling us all about it after he became certified as a Georgia volunteer firemen.

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Originally Posted by gianaameri

You should consider checking for CO2 as well because the better and proper filtering systems would convert any CO from the compressor into CO2.

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How do you check for CO2 in your tank?

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Originally Posted by rongoodman

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Originally Posted by gianaameri

You should consider checking for CO2 as well because the better and proper filtering systems would convert any CO from the compressor into CO2.

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How do you check for CO2 in your tank?

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CO2 cells do exist, one RB manufacturer monitors CO2, but I haven't seen a CO2 tester for tanks. I thought though that the "better" filtering systems absorbed CO2, I wasn't aware they could convert CO into CO2?

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Originally Posted by a64pilot

CO2 cells do exist, one RB manufacturer monitors CO2, but I haven't seen a CO2 tester for tanks. I thought though that the "better" filtering systems absorbed CO2, I wasn't aware they could convert CO into CO2?

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The Liberty Mutual site ( http://www.libertymutualgroup.com/om...=1138364693273 ) says the following:

"Carbon Monoxide (CO) Contamination
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CO (a colorless, odorless gas) ranks as the most dangerous compressed air contaminant. Headaches, dizziness, unconsciousness and death can result from exposure to elevated CO levels. High-pressure compressors are often equipped with a catalyst which converts CO into much less toxic CO2. Both CGA G-7.1 Grades D and E (the most widely recognized SCBA air quality grades) list a 10 ppm maximum CO content. If a good air supply and a properly functioning, efficient compressor are in use, CO levels will be less than 1 ppm. Detectable CO levels above 1 - 2.5 ppm are abnormal and require further investigation.

Carbon Dioxide (CO2) Contamination
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Normal CO2 levels in outdoor air (i.e. 200 - 400 ppm) or indoor air (i.e. 500 - 2,500 ppm) are not considered hazardous. However, compressed air with CO2 levels that are within the "indoor air range" can create problems in SCBA applications. Some compressors are equipped with filters to reduce CO2 levels. CGA G-7.1 lists a 1,000 ppm maximum for Grade D and a 500 ppm maximum for Grade E air. High CO2 levels in SCBA tanks can produce many of the same symptoms as CO poisoning (see above). In addition, high CO2 levels increase breathing rates, which shorten SCBA usage time. One of the most common causes of SCBA air quality failures is excessive CO2 content."

But it seems a bit counter-intuitive to convert a gas that is hard to monitor (CO2) into a gas that is easy to monitor (CO).

Sent from my ASUS Transformer Pad TF700T using Tapatalk 4

I knew an automobile Cat converted CO to CO2, but that takes really high temps, I didn't know it was done in a breathing gas compressor, wonder if it's a platinum type of cat, and how it works?

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Originally Posted by rongoodman

How do you check for CO2 in your tank?

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I use a CO2 Monitor ( http://www.temc.it/en/diving/de-ox-b...oxide-analyzer )

Same sensor I have used in my rebreather for CO2 inhale side detection.

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Originally Posted by a64pilot

CO2 cells do exist, one RB manufacturer monitors CO2, but I haven't seen a CO2 tester for tanks. I thought though that the "better" filtering systems absorbed CO2, I wasn't aware they could convert CO into CO2?

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I use these filters for my compressor: http://www.lawrence-factor.com/Purifiers/Hyper.asp

They contain Monoxycon ( http://www.lawrence-factor.com/Libra.../Monoxycon.pdf ) which oxydises CO into CO2.

This is a good article on compressors/filtration: http://scuba.club.anu.edu.au/gear/co...rs_Article.pdf