Pony Bottle Flooded- Best Approach?

[Drew Sailbum]

Hey Dr. Bill...ideally the LDS dive shop (which I know all too well and not too crazy about) should be using a di-electric silicon when re-assembling your brass/steel valve to your AL tank. It's Dow Corning 111.

My money is on this one. I have seen many tanks develop the problem you describe, and I suspect bimetallic corrosion. Take a close look at the threads and seating base of the valve and I´ll bet you see some small spots where the brass is showing through. When that hits the tank in the prescence of a little salt water it just eats away the tank causing lots of little pits like you described.

The solution, as Mr.X said, is to be absolutely sure that tanks in service like yours are given the benefit of lots of TLC and the good lubricant, DowCorning 111 (aka Molycote 111). The tiny amount of salt water that always seeps down as far as the tank neck o-ring will start corroding a new tank unless the sealing lubricant has the properties of DC 111.

 

[redacted]

My money is on this one. I have seen many tanks develop the problem you describe, and I suspect bimetallic corrosion. Take a close look at the threads and seating base of the valve and I´ll bet you see some small spots where the brass is showing through. When that hits the tank in the prescence of a little salt water it just eats away the tank causing lots of little pits like you described.

The solution, as Mr.X said, is to be absolutely sure that tanks in service like yours are given the benefit of lots of TLC and the good lubricant, DowCorning 111 (aka Molycote 111). The tiny amount of salt water that always seeps down as far as the tank neck o-ring will start corroding a new tank unless the sealing lubricant has the properties of DC 111.

I can see how this may impact the ease of removing the valve. But how does it effect the sealing of the tank and the valve by the tank o-ring. Does the pitting occur that far (over 1/2 inch) away from the points of contact?

 

[wreckchick]

I have another guess...

Check the valve to see if it's cock-eyed. If a tank gets dropped on it's head it can warp the valve to the point where it won't seat correctly at the neck. If it's the tank, it will fail hydro. If the tank passes hydro, put a brand new valve on it and see what happens.

Rachel

 

[boogeywoogey]

Is there a comedy section here for complete arses......if so.....I will happily join it with Dr Bill and many others..

1. Look after your kit and your kit will look after you - Dr Bill's priceless moment, letting his pony fill with water...

2. Only let a qulaified technician handle your gear and take it apart - my priceless moment..dismantling technical equipment at the kitchen table and not being able to put it back together again.....


3. Please tell us your daft stories....


boogey

 

[drbill]

Boogeywoogey- Are you suggesting I took the tank apart before it flooded? Not so... only my LDS during visuals or o-ring replacements has taken it apart. I took it apart AFTER recognizing it was flooded.

Took it in to the LDS I bought it from originally today. It turns out there is significant pitting on the o-ring seat. Probably due to the fact that the &((%^*&) bottle would leak, emptying out the air to a level where water was pushed in through the faulty neck seal.

The LDS offered to sell me a replacement at full cost that was already 17 months into its five year hydro period. No thanks. A second LDS offered to sell me a damaged bottle... at full price. No thanks. I'm waiting for the 19 I ordered!

 

[Web Monkey]

19's are small and cheap. I wouldn't waste another minute on a troublesome "anything" that I was counting on to save my life. Enjoy the new tank.

Also, you might want to put a short hose and SPG on it so you won't go diving with an empty tank again. If you don't want to go for a gauge and hose, you can use one of the tiny screw-in "button" gauges. At least you'll be able to see roughly how much gas it contains before you use it.

Terry

Boogeywoogey- Are you suggesting I took the tank apart before it flooded? Not so... only my LDS during visuals or o-ring replacements has taken it apart. I took it apart AFTER recognizing it was flooded.

 

[drbill]

Web Monkey- I usually check the pony with a gauge at the shop before I leave each day. When I'm on the dive boat they normally top it off anyway. I agree that a gauge on the pony reg is a wise idea.

 

[boogeywoogey]

Hi Bill,

Apologies, no that was not my suggestion that you took your pony apart...but that might have at least been an excuse for a situation that should not have happened.

I just chuckled to myself at the funny things that happen when you don't want them to....that was all.

I did manage to piece together my manifold and valves by the way.

boogeywoogey

 

[drbill]

No apologies necessary since I misinterpreted your statement, boogeywoogey. That darned tank has been more of a nightmare than a life saver since I had to test it every time to make sure it still had air in it. My LDS couldn't figure out why new o-rings wouldn't seal it (at least not for long). Good riddance and I'm looking forward to my 19 arriving.

Bill