How to install valve?

[hockeymulder]

I'm going to put a 300 bar din valve (don't know which one yet) on my low pressure PST 104. Currently I have a yolk valve. Is there anything special I need to do besides draining the tank, unscrewing the old one and screwing in the new one?

About what pressure will the burst disk blow at on a 300 bar din? Just in case my local shop happens to accidentily overfill my tank.

 

[Padipro]

Personally, if the tank is cleaned for nitrox I'd let the LDS replace the valve because it needs to be cleaned for O2 service first. If it's not a Nitrox tank, if you can get the valve off in the first place, some of the tank valves I've had just wouldn't unscrew, I'd replace the O-ring and lube the threads before reinstalling the valve.

If I remember right the burst disk on one of the 300 BAR valves I have said 3800 PSI. But others may be different. Some people, like cave divers, double up on burst disks so there is no way the disk will fail during a dive, or overfill. Could be very dangerous if the shop isn't aware of that and isn't used to dealing with cavers. If the valve is used, again IMHO, I'd have the dive shop replace the valve and overhaul it while they're at it replacing the burst disk just to be safe.

Scott

 

[pescador775]

Hockey, a '300 bar' valve from (Japanese mfgr) may include a 5250 psi burst disc. Some manufacturers, like Sherwood use 4800 psi. These limits are set for 3500 psi WP tanks-- IOW, high pressure tanks. However, there are only a few high pressure tanks which accept a 3/4" valve so the valve manufacturers typically use lower rated discs in valves of the type that you intend to use. This is because they do not anticipate that these '300 bar' valves with the long socket and 3/4 inch neck will actually be used at high pressures, certainly not 300 bar. When inspecting the valve, be aware that some manufacurers mark the WP on the disc plug and some mark the BP, a big difference. Personally, I use 4800 discs on anything ranging 2400-3500 WP. Put a light coat of Krytox on the O ring, seat the valve with a wrench using enough torque to make metal to metal contact. Do not over tighten or tighten with mickey mouse tricks like striking the valve stem with the palm of your hand.