Oh no! My 72s are too small for tech classes! :(

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Rol diy

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In really old valves the burst disk was actually a lead plug that was designed to soften in high temps and then pop out. Those were used more in O2 valves than the scuba industry.
Seems That's more for in a fire than overpressure...
Didn't fire sprinklers do the same thing?
 

Wibble

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they are a federal requirement for all pressure vessels.
When they burst there is no shrapnel, just a loud noise and a very cold valve. They burst by being punctured by a needle. They are consumable devices and must be replaced. It's a sporty experience I've witnessed 3x in the last decade. Usually from valves that did not have them replaced at hydro time since they do wear out over time from constant cycling, though one was from a 2250psi burst disc *designed to blow around 3300psi* being installed on an AL80 for some reason which are filled to about 3500psi to cool to about 3000 and it went off. That caused me to jump.

The history goes back to boiler explosions at the turn of the last century and they are required on all pressure vessels regardless of use. In the EU they are required for pressure vessels for the same reason however they are actually banned on breathing vessels which is a nice exception they've made. Unfortunately I do not see that happening in this country.

Outlined in the image below as "one-piece safety" though there are 3-piece designs.

thermo_features__48043__07773__47130.1541452236.1280.1280__52132.1587243078.jpg
Thanks for that explanation. Very informative

Didn’t know it is a pin.
 

jtsfour

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Years ago I picked up my LP 108 doubles at a South Florida shop where they were filled to service pressure for a routine deco dive. The person who filled them told me that he had detected a slight leak in my burst disk, and he had fixed it. I assumed he meant he had used a wrench to tighten it.

Two months later I was at Cave Adventurers in Marianna, Florida, and I left them at the shop to be filled for a day of cave diving. When I came back, the shop was a mess. It looked as if a tornado had gone through it. "What happened here?" I asked. "Didn't anyone tell you?" someone asked in return.

It seems that the South Florida tank filler who "fixed" my burst disk had replaced the whole thing with a new disk suitable for a low pressure tank.

So if you want to know what it is like when a burst disk goes, just ask anyone who was at Cave Adventurers that day. I am sure the tale will be one to remember.
It’s stories like this one that makes me paranoid about any regular dive shop touching my stuff.
 

boulderjohn

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It’s stories like this one that makes me paranoid about any regular dive shop touching my stuff.
What is a regular dive shop? The shop that replaced my burst disk filled trimix tanks and was the most popular tech diving charter in the area.
 

tbone1004

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Thanks for that explanation. Very informative

Didn’t know it is a pin.
Not in most new valves. It’s an industrial carry over on some old valves and the last one that I had go was one of them so that’s what was in my head
 

PfcAJ

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I would LOVE to see one of these moving part pin burst disk things.

I’ve been in possession of a lot of old valves. USD, Dacor, both J and K and ever once seen what you’re describing.
 

Tracy

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I would recommend they find a different instructor. Anybody that allows al80s but not steel 72s has no real idea about gas volumes.
 

Diving Dubai

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Somebody shared a video several years ago from, IIRC, a dive shop security camera showing a burst disc let go. The tank knocked stuff over and spun around making a mess. It was impressive.
back in 07, when I was newly minted, my GF and I were on a dive. I was in the water, she was just about to make a giant stride - I mean literally starting to move, when the burst disc went. One of the crew reacted at the speed of lightning and grabbed her stopping her jumping. They changed her tank and calmed her down...

In the UAE all our AL cylinders were DOT and had burst disks, but our Steels were EU and didn't thankfully. It's a crap idea
 
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