firemedic8082
Contributor
I have a Faber LP95 and I recently got a convertible valve for it, when I took it to my LDS he changed the burst disc to a 2400 psi disc before filling the tank. My question is if this is the normal rating for an LP95 tank.
LP95 Valves
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The burst disk for 2400 psi tank should be rated at 4000 psi:
Burst Disk for 2,400 psi [VP-416] - $9.98 : Tech Diving Limited, a subsidiary of Scuba Training and Technology Inc.
NorthWoodsDiver
Contributor
I would assume a LP 95 is rated to 2400 psi +. in which case the + means plus 10% so technically that LP95 should be rated for regular fills to 2640 (or so). when a tank in hydro tested its filled to 5/3's its rated pressure. 2400/3=800 X 5=4000psi. so that tank is tested to 4000psi every 5 years. So it should be considered safe to 4000psi however you can add conservative-ness if you wish and add any burst disc you like below 4000.
If you ever get into more advanced diving and find a dive shop that will do it you can ask for a "cave fill" which is more like 3500psi in a LP tank. In which case you'd want that 4000psi disc at a minimum. This isn't necessarily legal or safe but its practiced in some areas and well documented on this site and others.
If I were you I would invest in a plug for anywhere between 3500-4000psi to minimize the risk of that 2400psi disc going by mistake. Burst discs are not exact nor predictable...
If you ever get into more advanced diving and find a dive shop that will do it you can ask for a "cave fill" which is more like 3500psi in a LP tank. In which case you'd want that 4000psi disc at a minimum. This isn't necessarily legal or safe but its practiced in some areas and well documented on this site and others.
If I were you I would invest in a plug for anywhere between 3500-4000psi to minimize the risk of that 2400psi disc going by mistake. Burst discs are not exact nor predictable...
First, a rupture disk rating is controlled by the hydrostatic test pressure of the cylinder, not the working pressure. A "+" rating gets you nothing extra on the burst disk value, nor does the lack of a "+" rating cost you anything.
Second, you may have a HP cylinder with a hydro test pressure of nearly 6000 psi but your valve manufacturer only rates his POS K valve to 4500 psi. Hmmm...guess which pressure controls?
Third, some manufacturers label their burst disks based upon the burst pressure, some based upon the cylinder working pressure. Don't assume that a plug labeled 2400 means it's designed to blow at 2400 psi.
Without getting into the merits of double disking, if you're going to do it, you should make sure that the fill station operator knows what you've done and let him decide if he is willing to risk filling it. Anything less is dishonest and deserving of a punch in the nose - and the forfeiture of your tank.
Second, you may have a HP cylinder with a hydro test pressure of nearly 6000 psi but your valve manufacturer only rates his POS K valve to 4500 psi. Hmmm...guess which pressure controls?
Third, some manufacturers label their burst disks based upon the burst pressure, some based upon the cylinder working pressure. Don't assume that a plug labeled 2400 means it's designed to blow at 2400 psi.
Without getting into the merits of double disking, if you're going to do it, you should make sure that the fill station operator knows what you've done and let him decide if he is willing to risk filling it. Anything less is dishonest and deserving of a punch in the nose - and the forfeiture of your tank.
OP
firemedic8082
Contributor
Thanks guys.
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