Burst disc question

[DiverTim]

I just recieved a brand new USD solid manifold that has never been used. I plan to mount twin steel 72's on it with a pressure of 2250psi. The burst discs state 5000R on them. Is this a correct disc or do I need another disc and how do I go about changing them? Thanks, Tim

[luis]

That sound like a burst disk for 3000 psi tanks. The hydro pressure for the 3000 psi tank is 5000psi.

Burst disc for a 2250 psi should be 3750 psi (the same as the hydro test).

Burst disc should release at the hydro test pressure with an allowable tolerance of +0%, -10%.

You can either have a good LDS replace them or you can do it yourself. You can buy them from a couple of on line shops. You need to know what size. There are two normal size threads.

When you install a new burst disc you need to tork it properly or it may release at an lower pressure. I don't have the tork values with me, but I can get them if you need it.

[pescador775]

Almost any shop should have the disc. More likely, they will sell a kit containing all new parts. Insert the gasket and then the other parts, the disc and plug. Northeast Scuba Supply will sell just the discs if that is what you want. The correct disc may be marked with the WP or the BP. Like Luis said, if it is marked with some odd number like 3700 interpret that as the burst press. I have never used a torque wrench to do this and see no need for it. Mainly, leaks arise when the gasket is miss-placed. It needs to go in first. As to torque, using a socket be very careful not to over tighten because brass is soft. The plug is 3/8-24, same as the LP plug in a regulator. Use a 1/2 inch socket. Test for leaks.

[pescador775]

I have an additional thought on this. If you don't have much experience with spinning wrenches it might help to use a torque wrench. Beg, borrow, etc. Most of the small torque wrenches are graded in pound inches and have 1/4 inch drive. If you don't have access to sockets to fit the small drive then an adapter would be necessary to fit a 1/2 inch, 3/8 drive socket to the wrench. Adjust the torque wrench to 60 pound inches. Adapters are common items at auto parts or hardware stores, or should be.

[1969ivan1]

Or you could just put the disc in with a wrench like most of us truthfully do.

[DiverTim]

I used to wring off bolts , but now I tend to be alittle less intense. I have a few torque wrenches....wish I had them years ago! Thanks, Tim

[JES]

.... When you install a new burst disc you need to torque it properly or it may release at an lower pressure. I don't have the torque values with me, but I can get them if you need it.

When you get a chance please post the torque valves for us.

[DiverTim]

Really, I've read between 50 to 120 in lbs, although 60 in lbs is 5 ft lbs and I would think that is plenty, but I really do not know. Tim