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Post by cnotthoff on May 22, 2019 10:44:52 GMT -8
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Post by nikeajax on May 22, 2019 11:02:08 GMT -8
GULP!  What a crummy way to go... JB |
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Post by nikeajax on May 22, 2019 12:19:19 GMT -8
Holy cats: I inadvertently left that page open on my web browser. I'm wondering just how long it took to fly around the station like that: three or four seconds?
YIKES! I'm sure our friend John will have something to say...
JB
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Post by technidiver on May 22, 2019 14:32:51 GMT -8
Remind me not to empty my tanks like that. Not a good idea to go through the burst plugs while the tank is standing.
TD
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Post by SeaRat on May 22, 2019 17:03:00 GMT -8
Charlie, I've never even heard of someone trying to relieve pressure through the burst disc. That would seem problematic to me, as these discs have that copper plate in place. This is not like an overpressure relief valve, where turning it a few turns lessens the spring tension and the ORV can vent. With the burst disc, it's always been a go/no go situation whereby it either bursts or doesn't. Unscrewing the burst disc won't seem to work until it actually is out, and then you have not only the cylinder rolling around, but also the stem of the burst disc becames a projectile itself and could be shot out with enough force to also kill someone. Yes, secure the cylinder, but the burst disc has usually three ports on it too, so keep out of the plane of all three of the ports. But then, you cannot be at 90 degrees either, as it might become a projectile too. Now, it would seem that a better means might be to secure the cylinder, then unscrew the holding nut (bonnet) to the valve stem with a big wrench until past the O-ring, and let it vent that way.  IMG_1043 by John Ratliff, on Flickr I'm talking about the large nut that holds the on-off stem in place in the lower left of this photo. John PS, looking at the photo I posted, that may not work either, at least on this AMF Voit valve. This is because of that pesky O-ring on the stem on this valve. I'll look at my USD valves and see. As I recall, the USD valves have a nylon disc that seats the top, and a gasket on the nut, and that's what I'm talking about unscrewing until past that nut gasket. On the Dacor "Low Boy" valves, this is called the "valve retainer" and "retainer gasket." |
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Post by SeaRat on May 23, 2019 6:02:19 GMT -8
I've been looking at my valves, and diagrams, and reading this study, and it appears that the valve in question is a Sherwood valve. I haven't gotten my Sherwood valve opened yet, but I did want to point out one thing. One of my earlier Sherwood valves has a plastic boot on the end to cover up the area of the valve that allows us to take the valve apart. Because of this, these valves may be more suseptible to corrosion, as washing the valve off with fresh water would be more difficult.
John
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Post by vance on May 23, 2019 9:48:06 GMT -8
I once saw a huge cylinder fly around and ricochet off bulkheads and machinery for what seemed like an eternity. It happened in the engine room of one of the destroyers I was stationed on. The thing was a comparatively low pressure, 150lb CO2 fire extinguisher cylinder! It made dents in the bulkheads and broke machinery. No one was badly hurt.
I never want to see that again, much less a cylinder filled to 3000 psig going off.
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Post by snark3 on May 27, 2019 12:02:50 GMT -8
There's a thread about draining tanks with stuck valves on the VDH website(Why its a good idea to wash your gear in fresh water). The consensus there was not to loosen the burst disc retaining bolt, but to drill a small hole (1/16" MAX) through the burst disc.
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Post by nikeajax on May 27, 2019 13:07:38 GMT -8
Skip, ya know, I was thinking maybe that's how it should be done, but I didn't want to say'ny thing just in case I had faulty logic! John once sent me a story about some guy who'd tried to take the valve off of a medical tank filled with pure Oxy... Super-duper-extra-bad idea! I think he used a chain wrench to get it off: the heat from the friction caused a big explosion and took his arm off. Man that story had a BPF(butt pucker factor)of 8--grizzly!  JB |
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What a crummy way to go...
