Burst Disk Questions...

[IowaCaveDiver]

I am swapping a few valves around and setting up some tanks I picked up and a few questions popped into my head I wasn't too sure of. I would imagine that the majority of cavers either double disk or plug their burst disk ports on the valves/manifolds to enable them to get those lovely north florida fills... so here are my questions:

-Double disk best practice.... could you use two older disks together "safely" assuming the are resting one right on top the other with the indentation from previous use going the same direction (hey, i'm on a budget here...) i'm thinking i could salvage some disks from the old k-valves i'm replacing?

-if you're doubling up disks, do you have to worry about the burst rating of the disk you're using.... I would guess (i'm not a physicist) that if you had two 2250psi burst disks it would take double the pressure to burst them... hence 4500psi? Again, i majored in english in college not math nor science.

-do many of you just replace whatever stock disk is provided with a single 5500psi burst disk?

-I pulled an old dacor valve off a steel tank I picked up and upon examining it noticed a port at a 45degree angle facing downward just below the valve knob. Looked like a burst disk port and the port that the actual burst disk was in looked as thought it were probably a j-valve and had been converted. I pulled the lower odd plug and found the equivalent of an HP port. I tried the plug (it isn't a burst disk plug) in the burst disk port and it fit perfectly... it had an oring on it for sealing. So this got me to thinking... could i just use this instead of a burst disk and plug? Then it got me to thinking... why not just use a normal regulator port plug? I pulled one out to find that a LP standard size (scubapro in this case) fits perfectly into several of my valves burst disk port.... can I get away with just putting one of these suckers in there?

I would imagine the only place you might run into issues pumping tanks with valves doctored up like this would be at a local dive shop... most cave outfitters wouldn't give it a second look.

What else besides doubling up standard disks are people using to eliminate the worry of blowing a disk while getting a fill? Unless I learn differently, i'll probably just stick to doubling up to new disks in each valve i set up, however if a more cost effective method is available that is just as "safe"... i'm game.

[Sludge]

Ever considered burst disks rated for the pressure at which you plan to use them? I have "3500psi working pressure" disks in all my manifolds. "3000psi working pressure" disks in my stages.

[Line Squirrel]

Please don't double disk...

Double "disking" is akin to a solid plug...by doubling up a couple 3K disks (for example) will not blow at 6K, probably much much higher. The problem is, nobody really knows when it will go, at this point, it's unpredictable.

The plug (or nut) that holds the disk in place is designed with a sharp edge on it that is intended to cut the copper disk at a specific psi (depending on the thickness of disk course). By doubling up the disk, the second disk isn't "seeing" that sharp edge, it's seeing a much larger radius...if you can call .00? rad large.

I hope this makes sense...

[cavediver27]

Ever consider ss "no-blows"? Lots of us using them.

[Line Squirrel]

Ever consider ss "no-blows"? Lots of us using them.

Never heard of them....what are they?

[Jason B.]

Never heard of them....what are they?

Stainless steel burst disc replacements that do not blow - hence the name, no blows.

[mfascuba]

Stainless steel burst disc replacements that do not blow - hence the name, no blows.

I run them in all my steel tanks, they are great! In AL, I use the rated discs.

Mark

[chilldive]

SS disks work good. No worry about a disk bursting while on a dive. For out of the water, if the pressure builds too much due to heat, etc, the valve o-ring will rupture before the tank does.

[IowaCaveDiver]

now that you mention it, I had heard of the SS disks... where can you get them? I don't exceede rated pressure on aluminums, but steels I think it is common practice, at least in this area, to fill LP steels to 3600-3800psi.

[cavediver27]

now that you mention it, I had heard of the SS disks... where can you get them? I don't exceede rated pressure on aluminums, but steels I think it is common practice, at least in this area, to fill LP steels to 3600-3800psi.

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.