Legality of "cave fills"
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Wookie
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If I was a certified cave diver that enjoys the benefits of "cave fills"...... which I am not....... I would ignore this thread and let it just go away.
Burst discs are rated to blow at the test pressure of the cylinder. Not very accurate devices though
They make a mess if they blow when the cylinder is in a water bath
Also make a mess if a storage bank (350 bar 50L) cylinder burst disc goes when the cylinder isn't secured. They spin around like a break dancer and take out everything in their path. Strangely fun to watch
They make a mess if they blow when the cylinder is in a water bath
Also make a mess if a storage bank (350 bar 50L) cylinder burst disc goes when the cylinder isn't secured. They spin around like a break dancer and take out everything in their path. Strangely fun to watch
Capt Jim Wyatt
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I have never seen so many people get off the floor as fast as when a burst disc blew in a tank at a dive shop. It was upright on a tile floor and had the old-style burst disc holder that blew air at right angles to the axis of the tank. It fell over, of course, and then rolled until the air stream was parallel with the floor. Then it started to spin at high speed and bounce off other stuff, zig-zagging around the room. Everyone climbed everything in sight to get out of the way. (Me? I jumped up onto the corner of a glass display case.) It was pretty amazing to watch, but not fun. Also amazing is just how well motivated people can climb just about anything. It was lucky that it pretty much stayed on the floor because it never happened to hit anything that could launch it.
The new style holders that fire in opposing directions are *much* safer when they blow. Noisy, but not exciting. Sometimes, boring is better. This is why we're taught not to accept the old-style disc holders when doing a VIP.
Don't assume that a cylinder behaving like that will stay on the floor. The write-up on how a firefigher was killed when one went airborne is pretty sobering. https://www.cdc.gov/niosh/fire/pdfs/face201810.pdf
But if the burst disk nut is in place, the tank _will_ just sit there (making lots of noise).
The guys at this fire dept decided to drain their (full, out of hydro and corroded) scuba tanks by removing the burst disk nuts. What happens when one does that is not exactly what I'd call an "accident".
I'm just saying that once it starts converting potential energy to kinetic and physics takes over, regardless of how it got that way, it's not a safe assumption that a moving cylinder will remain at floor level, especially if it hits something and causes additional damage (like shearing off the valve).
So you'd put a higher-rated disk on an LP intended for cave-filling? Just enough to cover the pressure of the cave fill, or substantially higher?
The risk of doing that is that the tank itself blows, but that's a risk you've assumed when you overfill it. On the other hand, if you weren't going to cave-fill it deliberately, presumably you'd be want a burst disk appropriate for its rated pressure, right?
(Keeping in mind they're imperfect.)
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