Near reg failure - all ok

[Kimela]

On a recent dive trip, on the very last dive of the trip, I noticed my regulator began to breathe hard at the end of the dive. I wrote a message to my dive buddy that it was breathing hard, but since we were right below the boat and I still had over 1000psi left I didn’t worry about it too much. I experimented to see if it breathed harder if I was vertical or horizontal and noticed it would change, but it wasn’t consistently worse in any position. Back on the boat I couldn’t get my regulator off my tank without assistance. I enlisted another diver’s help, thinking my hands were too wet or I was too old and feeble – but he couldn’t get it either. Got the dive guide involved and he was checking to make sure the tank was fully off (it was) and reg was purged (it was). So as one person was purging, the other was loosening the reg off the tank. When it finally came loose, the tank spewed a cloud of white powder that settled like white chalk on the tank and everything around it.

I’ve since learned that the white stuff was aluminum oxide and that this probably happened because a previous diver had breathed the tank down too low, and it got refilled without anyone knowing. Evidently, my reg was breathing hard because the filter in it was doing its job as expected. The dive op cleaned my reg and (I assume) changed out the filter. When it comes to my gear, I’d rather not leave it up to chance, so I’ve already sent it out for servicing.

I’m curious about a couple of things. Why does letting a tank get too low result in this situation?

I have an air analyzer – haven’t used it in a while – but would it have detected this problem? Would aluminum oxide have shown up as a toxic substance in the air?

Someone elsewhere mentioned that if this had happened at depth it could have resulted in a complete out-of-air situation very quickly. Assuming that is true, would I at least experience ONE breath of hard-breathing before going OOA? I’m guessing my lizard brain is now fully alerted for hard-breathing to signal a threat, so I’ll notice subtle changes in how my reg is breathing. Will there be one breath – or is there the possibility I could go OOA without notice if this were to happen in the future?

When refill stations get the tanks back I’m guessing they do NOT check the air pressure before refilling. So how can this be prevented or predicted or … anything?

 

[rx7diver]

On a recent dive trip, ...

When refill stations get the tanks back I’m guessing they do NOT check the air pressure before refilling. So how can this be prevented or predicted or … anything?

An oxygen analyzer (nitrox analyzer) would NOT have detected this issue.

Maybe when you went head down, the powder (or slurry) entered first the valve's dip tube, and then your regulator.

Yes, it's possible you might suddenly have NOT been able to get a breath at depth. This is where having an attentive buddy who has consummate buddy skills is a good thing.

One of the most valuable things I learned early on in my open water training is just how long a relaxed diver can go without breathing, even after he/she has done a normal exhalation.

rx7diver

 

[Trace Malinowski]

When I worked as a dive instructor in the Caribbean, we would have 40 - 50 cylinders filled and ready to load in the morning and afternoon. Once we tied up from the two-tank afternoon dives, we'd start filling. We just hooked up as many as we could as fast as we could. A cylinder could have been empty or may have even contained water and we wouldn't have discovered it until it was a problem.

 

[davehicks]

Nothing you could have done to prevent this. The only thing you might have done differently is to end the dive as soon as it started getting difficult too breathe.

 

[johndiver999]

Wow, good lesson. If your life support equipment isn't working right, you should abort the dive and figure out what is going on. You are lucky is happened shallow, because if it happened at depth, the required gas flow requirements could have made it very hard to get air from the reg. I guess the filter was so damn clogged that it held a slug of high pressure air and made the yoke super tight. It had to be terribly clogged to do that.

This was not from one person letting a tank get low. This is caused by negligence on the part of the tank owner and not doing VIP's on a reasonably frequent basis. It will take a while for that much corrosion to occur. I would have demanded that the operator spot me a $100 or so for the reg over haul. I would personally be running clean water through all the second stage hoses as well.

I've never had that happen, but it is another reminder to be careful and one more reason why I love my pony bottle You can do everything right and still need a pony bottle.

 

[MaxBottomtime]

Oxidation happens inside an aluminum tank when water enters it. This can only happen when the tank is empty, not low, or when being filled from a poorly vented compressor, such as one on a boat. There is a chance that other tanks from that boat are also oxidized. I would insist on VIPs immediately.

 

[Kimela]

I would personally be running clean water through all the second stage hoses as well.

When I sent in my reg I wrote up exactly what happened - and have spoken via phone - to make sure they understand just how extensive the need for cleaning may be. I also want to make sure my hoses are in good working order.

 

[lowwall]

This is exactly what the dip tube is supposed to prevent. Either the tube was missing or there was a shocking amount of corrosion in this tank.

Either way, someone needs to be opening these tanks and checking what's inside them.

 

[Kimela]

Nothing you could have done to prevent this. The only thing you might have done differently is to end the dive as soon as it started getting difficult too breathe.

This is such an interesting issue and learning experience for me. When the reg began to breathe hard I actually thought "well, this is the second trip I've used this reg on and I remember Roger saying he didn't think it would breathe as easily as the old one" and I actually wondered if my head was playing games with me. Then I realized the breathing was like a wheezing, and knew it wasn't in my head. When it happened I had been shallow enough, long enough that my safety stop was complete - no reason to panic - but if it had happened on one of the dives we were at 80-90ft ... yikes.

So this is when I rethink just how far away from my buddy I'm comfortable being. Might be revisiting this.

 

[Trace Malinowski]

Either way, someone needs to be opening these tanks and checking what's inside them.

In my experience, managers never venture into the fill shed or dock. The staff never knows who exactly is in charge between captains and instructors of different specialties and seniority. If you do anything beyond the basics that no one told you to do, you won't get paid for your time, and you might even get in trouble for doing it.