I see people here from all sides of diving each getting a different message out of this fatality. Its a very tragic fatality, and gas issues can be very scarythey are impossible to test for without specialized equipment, and divers as a whole tend to be very trusting of their dive shop. Its scary to think that they could make a mistake, and we dont want to believe that we can make a mistake.
I dont think communal tank use is very common, Im used to seeing divers get assigned to a tank(s). Gas testing is not covered in OW classes, so I guess OW only divers are trusting the shop or dive master to provide them the proper mixture.
Ive also never seen someone take a tank from someone else, especially if assigned to a set of tanks. The nitrox label probably wouldnt help: if they dont know what it is, its easy to assume its just the name of a shop, or a cool looking sticker.
You can limit the use of your technical tanks by using DIN valves in the primarily yoke world, and by leaving stage kits on the tanks. Additionally, putting a label with your name over the mouth of the valve might help them to realize they are grabbing the wrong tank. The example given on a 80% mix should have the MOD marked (deco tanks should always have the MOD, since that mixture is less likely to change than a stage) and it should have had a stage strap, making it difficult for someone to grab accidentally.
As far as mixups somewhere in the system that accidentally provide someone with a tank with the wrong mixture
the only solution is to analyze your tanks.
When it comes to the nitrox sticker, it is not a solution at all. Air is a nitrox mixture. Probably the better term for what we call nitrox is enriched air nitrox, which designates that you are talking about something other than air.
The nitrox sticker doesnt give you any information at all. Its like putting a sign that just says hill on a ski slope. The skier still has to analyze the hill to determine if its safe to ski down, just like a diver still has to analyze. Since there is the potential for personnel errors or mechanical breakdowns to put an EAN mixture into an unmarked tank, even the unmarked tanks should be analyzedjust because there isnt a sign saying the slope is a black diamond doesnt mean its the bunny slope. However, the people who are supposed to stay on the bunny slope arent taught how to analyze a hill. Of course, its not very often that a non-nitrox trained OW diver grabs a nitrox mixture and dies, and thats not what happened here, either.
Even labeling with a percentage of oxygen is not the complete solution. That label means nothing as soon as the tank is out of your sight, and sometimes sooner! Think of it like a for sale sign on a house. Could it be that the realtor put the sign up in front of the wrong house? And what if the house sells and the person hasnt taken the sign down yet, is he or she going to be happy finding strangers peeking into windows to see if theyd like to make an offer?
The best solution for tank labeling is a label that goes over the valve opening, so that any usage of the tank means the label is removed and destroyed. However, since the opportunity still exists for the sign to be put in front of the wrong house it is still not a complete solution.
The only solution that really works is to analyze before each dive. Even then, you could have a faulty analyzer, and setting up a group of multiple cells that use voting logic is expensive.
Many divers dont dive that often. If they owned an analyze, the cells might die between each trip, and most divers dont want the hassle of buying a limited-life product before every dive trip. Even if they did, they could easily forget to order the cell until its too late.
The better solution is analyzers on the boat. But youll have plenty of people who dont know how to use it, and it could take a significant amount of time to get all the tanks analyzed between each dive. The units will also probably get ruined quickly in the boat environment.
I dont have any statistics to show how rare this type of death is, but I think that shows how rare this type of death might be. Its very tragic when it happens, but I cant recall that many fatalities due to either o2 or CO in breathing gases. While I would love for everyone to analyze before every dive, Im sure we have plenty of technical divers who dont analyze, especially for CO.
My o2 cell has been dead for months now, and I have several tanks that arent analyzed. After this tragedy, Im thinking I should probably remedy that before my next dive trip, and Im sure Im not the only one. I know in the grand scheme of things, o2 cells arent that expensive, but its one of those things that is easy to put off when your gas supplier knows you by name and you develop some sort of trust with them. The real lesson here is, dont trust anyone, not even yourself and your memoryanalyze yourself with your own well kept analyzer, and label yourself, in a way that minimizes the risk of someone using your tank or for your label to get outdated.
I know we see people on here posting about designing contraptions for scuba divers for different classes
I think it would be very nice to see a very cheap and reasonably accurate o2 sensor that could be used on the 1st stage or 2nd stage of an existing regulator setup. It would need to be cheap, lets say $10, and last for a while. I dont think you need an LCD readout, something color coded maybe, or a tri color LED, I dont know. Something that would tell people something like this is air, this is EAN and this is deco. That would be enough information for someone trained on air to realize the tank is not air and they should not dive it, and for someone trained on deeper diver to realize they were about to breathe a deco mix. Of course, even with something like that, Im sure people would make mistakes, and it wouldnt stop CO deaths at all
but I think knowing your PO2 is one advantage that rebreather divers have over OC, and it would be great if there was a simple way for OC divers to know their PO2 or some rough estimate.
