SpudFiles

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.

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.

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

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

jakethebeast wrote: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.

jackssmirkingrevenge wrote:

jakethebeast wrote: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.

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)...