Burst disk burst pressures

[PeteS]

There was a thread about this a while ago, but I went away without many answers. That may be because there are just no acceptable answers, but I figured it was worth raising the topic again in case someone might shed some further light on this.

It would be wonderful to have a chart that showed bursting pressures for different materials and diameters.

If it was possible to calculate the bursting pressures for different diameters of a material based on testing at one diameter. It would become feasible to test a bunch of materials for one diameter and them calculate the rest of the table. That or just use a formula to calculate the burst pressure for the desired diameter.

So, does anyone know what the relationship is between burst pressures for a given material at different diameters? I may be wrong, but it seems like this ought to be something that would lend itself to calculation.

[Ragnarok]

Completely off the top of my head, my assumption was the burst pressure would be calculated/estimated by:

Ultimate shear strength of disk material * disk thickness * 4/ disk diameter

However, that's assuming the disk failure is a material failure at the circumference - and I'm not sure that's a sensible assumption. I haven't really ever worked with burst disks much myself, but I know I've seen a lot of pictures of disks failed in the centre...

Also, it doesn't account in the slightest for how well the disk holder actually grips or supports the disk - and that's such a big factor that any look-up chart would be useless. Still, if you want to make a very rough assumption, burst pressure will be approximately proportional to material strength and disk thickness, but inversely proportional to disk diameter.

[jakethebeast]

From my experiences, I have noticed that it´s not always what people say. As an example, people here told me that 10mm dia disk cutted from the side of a beercan with 10x and 45cl chamber wouldn't burst. In my test, it bursted just fine.

So id say just experiment, that's the best way to accomplish these things

[jakethebeast]

edit: OOPS, havent got used to the new forum yet, sorry

[jackssmirkingrevenge]

So id say just experiment, that's the best way to accomplish these things

Given all the variables as rightly pointed out by Rag, I would have to agree.

[PeteS]

So id say just experiment, that's the best way to accomplish these things

Given all the variables as rightly pointed out by Rag, I would have to agree.

I was afraid that would be the answer. I figured it was worth asking though.

Thanks for the replies.

[wyz2285]

I used to have a table for bursting pressure of aluminium foil at 1/2 inch and 3/4 inch diameter. Lost it a while ago, it's terrible choice for high mixes. It's pretty linear though, like one layer holds 5 psi and 2 layers hold 10 (for the same diameter)...