Mistaken identity: travel and deco gas mixup

[ErikH]

Also permanently marking tanks for MOD (in addition to analysis tape) could help.

In this case it didn't, because tanks are user for different gasses, MOD labels are put on the tank when they were analysed. Keeping the same tanks for the same mix would help. But I already have too many of them

 

[CuzzA]

So have you determined a solution for your crew to prevent this from happening in the future?

 

[lv2dive]

Which is why I said *permanently* marking tanks with MOD could have helped to prevent the problem. [emoji4]

My SO and I have over a couple dozen stage and deco bottles (40s and 80s) all with permanent MOD markings. (And yes, we do actually use then all!). I do understand keeping up with maintenance gets to be hassle, never mind the space issues! So I realize permanent markings may not be practical for everyone.

An alternative I've used when I've not had access to rentals with MOD stickers on vacation, is to make my own. A thick sharpie and blue painters tape or white/light-colored Duct tape along the bottom of the tank to mark the MOD before getting it filled if possible works pretty well. Just a thought!

I've found the discussion on the thread interesting. This isn't an issue I would have expected to surface with a team conscientious about analyzing their gas, so I sincerely appreciate the sharing of the story.

In this case it didn't, because tanks are user for different gasses, MOD labels are put on the tank when they were analysed. Keeping the same tanks for the same mix would help. But I already have too many of them

 

[Centrals]

The tank was incorrectly labelled. Therefore it was NOT mistaken identity, it was simply human error.
If you have a lot of tanks to analyse and label etc etc, the content of each tank has to be verified again by a third party. Tedious, yes but safety first.
I always analysed all the tanks that I was going to use and labelled with my own name and the MOD. Never ever relied on someone else to do this.

 

[ErikH]

Which is why I said *permanently* marking tanks with MOD could have helped to prevent the problem. [emoji4] [...]

The tank was incorrectly labelled. Therefore it was NOT mistaken identity, it was simply human error.
If you have a lot of tanks to analyse and label etc etc, the content of each tank has to be verified again by a third party. Tedious, yes but safety first.
I always analysed all the tanks that I was going to use and labelled with my own name and the MOD. Never ever relied on someone else to do this.

Permanent marking might work most of the time, but I guess in my case (where tanks are shared quite often between friends) correctly labeling BEFORE filling instead of afterwards might reduce some risk.
All the tanks were analysed directly after filling by myself and contents were written on a label (not tape) attached by rubber band to the valve. I consider this one of the bigger problems, as it is too easy to remove and too difficult to read. MOD markings were not on the tank yet at this point. The diver who made the error analysed his own tanks as well - but switched the two tanks when marking with MOD and analysis label. So in this case 'Always analyse your own tanks' failed anyway.

[...] I've found the discussion on the thread interesting. This isn't an issue I would have expected to surface with a team conscientious about analyzing their gas, so I sincerely appreciate the sharing of the story.

This is exactly why I put the story online and I hope it might safe a reader from making the same mistake.

So have you determined a solution for your crew to prevent this from happening in the future?

- Fill tanks with correct MOD label already in place
- Use taped labels for filling instead of rubber banded ones (need to mark them anyway with fill instructions)
- NEVER analyse and label more than ONE tank at a time, unless it's a twinset

Thanks all for your contribution and dive safe!

 

[Centrals]

deleted.

 

[Reku]

Like quite a few others here. I keep the analyzer on the tank until after it has a label and I do another analysis at the site before the tanks go into the water. It's quick fast and painless and makes sure I don't die.

 

[bradells]

There can be a simple solution ... one that I've done for quite a while now.

1. See a tank?

2. Grab a piece of tape ... Slap it on there.

3. Test pressure, and write it on the tape.

4. Test O2, write it on the tape.

5. Initial and date.

6. See another tank?

7. Repeat steps 2-6 until you have enough tanks for the day.


I test pressure before O2 as sometimes, very rarely, O2 has been added, but not topped off in the pile of tanks. Easy to see that it is not at pressure yet, and you don't have to deal with mostly pure O2 or analyzing and then finding out it isn't close to full ....


On charters, it's 'simple' enough to remember 2-3 tanks worth of numbers (especially with very talented mixers to hit w/in .1%/1bar everyday PP blending), but when the sometimes too helpful staff see you analyzing, and turn your back, sometimes ... they may just grab your tank and are down the dock before you label it ......



BRad

 

[beester]

Next time you do ressel, what you can do is drop the 50% (MOD21) stages a bit further in closer to where you dropped the "travel" gas (32%). If you take the shallow circuit and get to the 2nd T you can swim a bit further (very close to were it drops of first from 23m to 30m) and drop there (about 350m). If you take the deep route after first T, you can do the same, there are some sections which are a bit deeper (bottom) than 21m but the ceiling is 18m/19m so if you stay close you stay within MOD.

Couple of advantages:
- If you swim out on "travel gas" you can basically drop travel and 50% at the same spot saving time. (because 40-50m further the cave drops below 30m in any case).
- If you scooter in you don't need a travel gas 32%, it takes about 15-18 minutes to get to the shaft with drops, so you can scooter in on 50% and switch to backgas or bottom stage at that point. Gaining time and reducing workload (1 less stage).
- If you swim out doing deco on 50% this profile will match your normal deco profile and give you some time before the little spike were you go above ceiling for a moment at the first T (7m, and usually you are then still on the 12m-9m decostop in runtime).

Coming to your near miss... YIKES!!!! Glad you dropped early, this could have turned ugly very fast.

My procedure to avoid above is following:
- My O² and 50% stages are permamarked. If someone wants to lend them (happens often enough) and they need to use them for something else they need to tape over the permamarkings. After returned I empty them anyway.
- My other stages are not permamarked but are marked before filling with MOD on both sides using tape.
- Before stages are filled they get a tape with the to be filled content (MIX= 32%), then after filling an d analysing this is completed (MIX=32%, A: 31.8% D:13 JAN). Avoiding any mistakes. I know what needs to be in the stage because of mod labels and label already stating MIX %. The O² check just confirms this.
- Before I mount regs on the stage setting up for the dive I analyse again and sign the label off with my signature. So I know before I put on the regs that fills are good and matching mods.

Dangerous stuff this stage diving ;-)

 

[bl6394]

I guess I don't get the debate... I'm personally responsible for analyzing and labelling any gas I breath. I have my own O2, CO, and Trimix analyzers to ensure that I can always do this. I personally analyze each tank and label it appropriately (duct tape works fine for this), and confirm which gas I'm breathing during the dive.

If somehow the tank is outside of my control and the mix could be adjusted - I will confirm the analysis and labelling again before I breath it.