Tank / Gauge Failure

You didn't have the valve tightened up enough. The pressures these tanks hold , just the slightest small void will blow the o-ring at the neck. I use 90 durometer o-rings when replacing the valve , and finish tightening the connection with a rubber mallet. What size tank is that ? I have extra 0-rings for the larger tanks with the 7/8 -14 unf valve. If so, pm me and I'll send you a couple.

When I did an inspection of the inside of my scba tank I just hand tightened the valve and had no problem.

Was that a replacement o-ring or ..............? I haven't had to crank down on any of my valves for a non-leaking seal either......yet. That's with brand new o-rings correctly sized. Just hand snugged with a dab of silicone grease on the o-ring's mating surfaces. I did have a bottle gauge seal let go, though. Wife and cats didn't respond well to that

My gauge crapped the bed and I'm waiting for a replacement.

You're only suppose on hand tighten the valves on carbon fiber tanks

I have to take back what I said earlier about a leaky gauge seal. I assumed it was the gauge because I had just reinstalled it before the leak occurred. Wrong! The valve to tank O-ring let go right behind the gauge just like the OP's. Are these a common size in mm? My calipers say 18mm ID x 3mm CS on the blown out ring and valve stem. No spares on hand ....

what brand of tanks and valves are these problem children, that can't keep an o-ring in it's groove?

Mine is a Tuxing 2L bottle with a cheap Palm Beach Air valve.

I found an O-ring in my Leshiy 2 reseal kit that fit the valve stem and bottle groove closely. Snugged the valve up firmly by hand and pumped it up to 300b last night. It's held pressure so far .......

Bulging o-rings indicate one of three possible issues.
The o-ring is undersized for the application.
The valve hasn't been tightened down enough.
The durometer of the o-ring is too soft for extreme high pressure use. Most high pressure o-rings are Buna 70 or Buna 90.

I think Humdinger has the Humdinger of an answer here. Cheapo soft O-rings are a very likely suspect. I suspect a soft O-ring is the failure we see here. The failure our OP experienced is extrusion, I'd recommend getting the correct O-ring from the tank manufacturer. The valve being loose on the tank would produce the same failure type, harder O-rings resist extrusion better. That had to be loud and scary when that happened. I plan on filling my CF tank inside a really heavy duty plywood cabinet. I can monitor pressure at the compressor.

Sumpin’ ain’t right here. In the enlarged photo below of the OP’s valve and tank neck I see metal on the valve displaced and what almost looks like a roll pin end view.

rcs9250 said:

Sumpin’ ain’t right here. In the enlarged photo below of the OP’s valve and tank neck I see metal on the valve displaced and what almost looks like a roll pin end view.

View attachment 499858

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I think the o-ring blew out farther and the roll pin is just ice built up

kayaker said:

I think the o-ring blew out farther and the roll pin is just ice built up

Click to expand...

I ain’t buyin’ that. Something was under the valve flange when it was tightened. Maybe the O ring was the wrong size or something. I have installed literally thousands of scba and scuba valves and O rings in hundreds of industrial applications and never ever had an O ring extrude like that. We aren’t getting the whole story here.

Yup I think the O-ring is just blocking the view making it appear a chunk of metal went with it. The fitting above looks frosty as well. Scary stuff imagine your hand being there when that let go. Have worked with compressed air for a lot of years professionally, I have a healthy respect for 3-4 atmospheres, I reckon that respect should be 10 X for HPA compressors and tanks, esp. when manufactured by folks with zero liability exposure. Play careful guys.

I have had o rings pop out like that on a Ninja tank. It was caused by the valve not being tightened down enough. I let the air out, fixed the o ring and refilled. The tank/regulator worked fine after that. It wasn't a big deal.

To tight ! Looks like you might have to junk the tank . Take it apart you will know soon enough .