After 41 years I almost bought it today...

[Seabear70]

Aluminum will corrode. It's not actually Rust Fe2O3 but instead Aluminum Oxide Al2O3. And it could produce crud in the tank...

 

[wolf eel]

[Aluminum will corrode. It's not actually Rust Fe2O3 but instead Aluminum Oxide Al2O3. And it could produce crud in the tank]

I know. But what I am trying to figure out is what would cause this?. I know the answer to that Bad air or moisture.

I work with Al in many different applications and still with out something then you have no reason for crud. I guess a hot fill will cause friction which in turn could cause the wall to flake maybe but I still do not understand how come I have never had anything fall from a tank ( I have owned about twenty if not more by now) Is it because I never let them go dry or because I never leave them open to let mice in or ? Al needs a catalyste and air is not it. Dry air I mean.
Cheers
Derek

 

[Seabear70]

I know. But what I am trying to figure out is what would cause this?. I know the answer to that Bad air or moisture.

I work with Al in many different applications and still with out something then you have no reason for crud. I guess a hot fill will cause friction which in turn could cause the wall to flake maybe but I still do not understand how come I have never had anything fall from a tank ( I have owned about twenty if not more by now) Is it because I never let them go dry or because I never leave them open to let mice in or ? Al needs a catalyste and air is not it. Dry air I mean.
Cheers
Derek

Ok, I know people get sick of me talking about my commercial experience, but I'm going to reference something that I ran into back then. When going into the water on surface supply, you need to have a non-return valve on the dive hat. The reason is, and I know a guy who lived through this, if the hose is cut near the surface while you are at any depth, the gas escaping from the hat can rip your face of or even vacuum out your lungs. Needless to say, we checked that Valve before every dive. We were all told that this is a one in a milion chance, and if we dove for 20 years we would be unlikely to ever see a non-return valve fail.

I have seen four of them fail on check out. It is unlikely that those four would have resulted in an injury, but who knows.

The point is that even if there is a infintessimal chance that something could go wrong, there is a chance that something could go wrong. Perhaps there was a small flaw in the tank that would never show up under normal inspection, perhaps that flaw allowed a small section to corrode by allowing very dry, though still having some moisture, to circulate arround it. Who knows?

I doubt we'll ever have more than theories about what caused this.

 

[wolf eel]

[you need to have a non-return valve on the dive hat. The reason is, and I know a guy who lived through this, if the hose is cut near the surface while you are at any depth, the gas escaping from the hat can rip your face of or even vacuum out your lungs.
I have seen four of them fail on check out. It is unlikely that those four would have resulted in an injury, but who knows.]

I agree.

The check valve can fail. It only takes a hair to allow air to pass. Commercial gear (i am) goes through more abuse then rec gear. It gets dirty as we become more complacent and we as Commercial divers get wet and stay wet longer which in turn takes the unknown and makes it less unknown. In the case of the check valve you check it and yes they fail from the test not at depth. (Or not that I have heard of)

I agree ****e can happen and when it does it comes on fast. I not only still work surface (hooka) and tank but I still have not had crud as to say in my tank.

Bad air or moisture both being diver or shop errors. The tank if taken care of should go on for years and never have trouble.

But i agree with you fully.

Cheers gone diving

Derek

 

[Laurence Stein DDS]

Did you look at the SPG when it wasn't delievering gas?? did you try a breath after you ascended a bit... there are a few things I oculd think of that would cause what you describe... One thing that is a slight possibility is that the valve was only cracked.. given time on the boat it would have read full pressure, and given you several breaths.. I try and teach my OC students to take a few test breaths on the surface WHILE looking at their spg, a valve thats only partially open will see the needle dip a bit then rebound.. Its usually the old salts that tend to get complacent, but as in your case your experience that also saved your butt.

I would also check your IP, if it is seriously off you can get some strange problems.. if its too low some regs are very hard to get gas from...

I was on a boat where a diver was complaining his reg "didn't feel right" I took a breath and it seemed very hard, same with his octo.. I hooked up an IP guage and it was 25psi, thats not a typo 25psi....

DrBill,

I'm inclined to agree with padiscubapro. A cracked tank valve is exactly what led to a personal rescue about 10 years ago.

I had to rescue an experienced divemaster from 8O feet. He rushed up to me with the two biggest eyes I've ever seen. Then he removed my second stage after not being able to clear my AirII (he had nothing to exhale and was unfamiliar with the purge). I knew it was coming and switched to the AirII with no problems.

We made a slow, safe ascent with a safety stop. Later he was found to have salt water in his lungs and spent some time in the Curacau hospital next to a corpse.

When we checked the diver's gear, we found that the tank valve was only turned slightly. Enough to give a pressure reading but not enough to supply the first stage at depth.

To this day, I check my SPG and VENT the entire system to read zero and then repressurize just prior to the dive. It is possible to check the SPG, turn off the valve and still show a full tank when starting the dive. When checking the air supply, I always look at the SPG, inhale and look for a pressure drop. An open valve will not move. A cracked valve will dip and return. A closed valve will dip and hold.

We have all been trained to do this but until it happens to you or a buddy you might not see the real necessity. It turned out that the rescued diver's buddy asked me following the dive, "What does it mean when the guage dips and returns?" I told him it means he was really lucky.

You mentioned remembering that you checked you guage. Do you remember when you checked the gage? Was it when you first assembled the system to make sure you tank was full? Did you only crack the valve to pressurize the system (been burned by too many blown "O" rings?)? I think we all have done something like this at some time.

Certainly checking the reg out completely is warranted and service so close to a failure is suspicious.

It is amazing you didn't lose it.

Regards,

Larry Stein

 

[drbill]

The tank valve was fully open to put that question to rest. No question about that. Believe me, I checked it (both before entering the water and after surfacing). In fact, the SPG showed 3200 psi topside (if I remember correctly) and I do test by taking a breath or two from the reg or inflating my BCD while watching the SPG.

I think SeaBear70 is right- we can propose theories on why this happened, but we can not at this point find verifiable answers.

Doc

 

[kwesler]

As a matter of post problem protocol, should we leave our gear set up EXACTLY as it was when the incident occured? Or try and trouble shoot ourselves, accepting the disturbance of "crime scene"? Opinions?...

 

[Seabear70]

Here's the rule of thumb...

If someone died, don't mess with there gear, wait for the professionals to come and look... In my area, I guess you'd wait for me. It's a small town...

If no one died, follow the wishes of the diver who had the problem. If He/she wants to know why their gear malfunctioned, I'll help them try to figure it out. And I'm certainly not going to stop them from trying to figure out why they almost died.

 

[kwesler]

Here's the rule of thumb...

If someone died, don't mess with there gear, wait for the professionals to come and look... In my area, I guess you'd wait for me. It's a small town...

If no one died, follow the wishes of the diver who had the problem. If He/she wants to know why their gear malfunctioned, I'll help them try to figure it out. And I'm certainly not going to stop them from trying to figure out why they almost died.

makes sense...I guess it the lesser of two evils to accept the fact that you may inadvertently eliminate the chance of finding the issue, in exchange for trying to find it yourself, with all the advantages-like diving the equipment again asap.

Ken

 

[mccabejc]

Dr. Bill,
It's fascinating that you did a CESA from 60-70 feet. Wow. And as I recall you said you started with your lungs half full. Did you actively expell air the entire time, or "aaahhh", or just keep your airway open?