Burst Disk Questions...

[BobK]

I got mine from EE in High Springs (only thing I ever bought there). I use them in all my steel cylinders but as others have said, not in my aluminum cylinders.

Be aware that if you currently have one piece burst disk assemblies you're going to have to buy the three piece assembly parts in order to use the SS burst disks.

I just use one piece 7250 PSI burst disks in my steels. Always the correct ones in the aluminums, I think those are ~ 4500 PSI.

[cavediver27]

Be aware that if you currently have one piece burst disk assemblies you're going to have to buy the three piece assembly parts in order to use the SS burst disks.

I just use one piece 7250 PSI burst disks in my steels. Always the correct ones in the aluminums, I think those are ~ 4500 PSI.

I've been using them for years in all of my Thermo manifolds; takes one ss no-blow and one nylon washer per valve.

[outofayr]

Do 2640 tanks only have 4500 discs (if original)?

Actually, they have 4000 psi discs if original (remember a 2640 tank is actually a 2400 tank with a 10% overfill).

Brian

[BobK]

I've been using them for years in all of my Thermo manifolds; takes one ss no-blow and one nylon washer per valve.

So you use an SS burst disk, then a nylon washer, then the one piece burst disk assembly with some copper burst disk in place ?

[cavediver27]

So you use an SS burst disk, then a nylon washer, then the one piece burst disk assembly with some copper burst disk in place ?

No, it's way simpler than that.

Here is how it goes: The nylon washer goes in first, then the ss no-blow and then tighten down the standard factory bolt, that's it. There is no copper burst disc used, that's what the no-blow is for.

[DA Aquamaster]

BUrst discs are designed to blow in a range between the test pressure and 10% below the test pressure. In other words for a 3AL 3000 psi tank, where a 5/3rd test pressure is used, the burst disc would blow between 4500 and 5000 psi.

For an exempt 3442 psi tank with a 3/2 test pressure, the disc should blow between 4650 psi and 5160 psi.

So in effect, if you put in a burst disc intended for a 3442 psi tank, it will have a minimum 800-1000 psi margin over and above what you'd get on a cave filled 2400 psi tank.

If you want overkill use a burst disc intended for a 4350 psi (300 bar) tank. It will be rated for between 6500 and 7250 psi.

It does not really matter where you dive, if you rinse the valve after salt water dives and change the burst disc every 5 years when you hydro test the tank, you will never encounter a burst disc failure.

[Sludge]

if you rinse the valve after salt water dives and change the burst disc every 5 years when you hydro test the tank, you will never encounter a burst disc failure.

Ding, ding, ding, ding, ding! We have a winner!

[chilldive]

No, it's way simpler than that.

Here is how it goes: The nylon washer goes in first, then the ss no-blow and then tighten down the standard factory bolt, that's it. There is no copper burst disc used, that's what the no-blow is for.

Sometimes the copper burst disk is attached to the factory bolt. In that case you need to peel it off before putting back in with the ss disk and nylon washer.

[chilldive]

It does not really matter where you dive, if you rinse the valve after salt water dives and change the burst disc every 5 years when you hydro test the tank, you will never encounter a burst disc failure.

Or you can put in a SS disk and never worry about it. I personally have about 20 tanks that I maintain myself on a regular basis, so it's one less thing to deal with and one less thing to worry about.

[cavediver27]

It does not really matter where you dive, if you rinse the valve after salt water dives and change the burst disc every 5 years when you hydro test the tank, you will never encounter a burst disc failure.

Not sure about your "you will never encounter a burst disc failure" as they do fail and have failed and will fail again. Is it common? No, but it happens.

The reason I use no-blows is that I absolutely will never have a burst disc failure. Just one less potential failure point.