Burst disc failure leads to over $2000 in property damage

[CuzzA]

@CuzzA , based on what you saw, do you think the newer burst disc assemblies with the 3, 4, or 6 radial holes would allow an accident like this to occur? In your post you mention the cylinder leaving the ground.

I believe it had 3 ports on it. To be clear the cylinder didn't take off like a rocket, but the force was so strong that it basically left the ground and did a flip landing on the value which broke the valve handle.

Aside from the noise, I was pretty shocked at how violent it gave way.

 

[scagrotto]

the new burst discs shouldn't allow this since the gas comes out the side of the plug.

It's not simply venting through "the side of the plug" that prevents this sort of problem. When pressurized gases escape from a container in only one direction there's force in an opposing direction that, if we were rocket scientists, we'd call thrust. Venting through the side, the end, or any other place simply determines the direction of thrust. The resulting acceleration in the opposite direction is what caused the OP's misfortune. OTOH, if the escaping gas is vented in multiple directions the forces can be balanced, so that there's no net thrust and therefore no acceleration.

A single hole, no matter where it is, will create an unbalanced force. Multiple holes that are evenly spaced and in the same plane won't.

Edit: If the disk ruptures in any kind of confined space the resulting air currents might still produce interesting results. I'll guess that's what happened in the incident related by CuzzA.

 

[tbone1004]

@scagrotto correct, I should have said sides instead of side. That said, even if it were to come out of a singular side of the plug, since it is off center, it would likely start to spin instead of lift since the force isn't coming out directly on the axis.

 

[claymore]

I had a burst disc go on an AL 30 when it was standing in the garage bungied to a shelf with my other tanks and never moved as far as i could tell. I believe that there are two types of Burst Disks. 3 piece type, washer burst disk and retaining bolt and the 1 piece type which has all the pieces blondes together as one unit. They are not interchangeable between valves.

 

[2airishuman]

Newer valves usually have a raised circular collar around the burst disc plug. I have wondered what effect this has on the thrust produced when the disc opens, since it would redirect the movement of air outward in, more or less, a single direction.

 

[tbone1004]

@2airishuman i think that's more to protect it from getting knocked around on that side of the valve. The modular valves have it sticking out the back since that side port is for the manifold

 

[NAND]

Learnt from this incident report.
Thanks so much for sharing this!!

 

[2airishuman]

@2airishuman i think that's more to protect it from getting knocked around on that side of the valve. The modular valves have it sticking out the back since that side port is for the manifold

I realize that's the purpose (combined with making the valve easier to handle), but I wonder about the side effect on thrust.

 

[guruboy]

I had a burst disc go on an AL 30 when it was standing in the garage bungied to a shelf with my other tanks and never moved as far as i could tell. I believe that there are two types of Burst Disks. 3 piece type, washer burst disk and retaining bolt and the 1 piece type which has all the pieces blondes together as one unit. They are not interchangeable between valves.

(emphasis mine)

That last bit is not correct. You can use either a 1-piece assembly or a 3-piece system in any valve as long as you get the correct size.

 

[2airishuman]

That last bit is not correct. You can use either a 1-piece assembly or a 3-piece system in any valve as long as you get the correct size.

I agree with guruboy and could post some sample photos. There are two sizes of burst discs in widespread use. Each of these is available in both 1-piece assemblies and the (older) 3-piece system. The 3-piece system is available flush, with a single outlet and slotted drive, as in the cylinder involved in the accident -- or in the multiple outlet, hex drive arrangement that protrudes from the surface of the valve somewhat.

The larger system is used by Sherwood/Genesis valves with most other brands using the smaller size.