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New burst disk idea ?

Posted: Mon Feb 09, 2009 10:42 pm
by trigun
I was at home depot the other day and saw they sold pvc sheet. It is fairly thin so it seems like a good burst disk. Has anyone else ever tried to use this material?

Posted: Mon Feb 09, 2009 11:05 pm
by starman
Is that the shower pan material? I have some of that as well. That stuff may be stronger than you think.

It's going to depend to the area of the burst disk opening. Because it's fairly thick, you aren't going to be able to use more than 1 layer at a time. Therefore, you're stuck with the burst point of 1 layer and that may be too high for a 1x combustion in a 2" burst opening.

I don't know for sure though...just speaking from rough recollection.

Posted: Mon Feb 09, 2009 11:18 pm
by trigun
I think we are discussing the same material yes. It does seem tough so for a hybrid it would ? I guess it is time to spend more $ then and test it

Posted: Mon Feb 09, 2009 11:59 pm
by starman
trigun wrote:I think we are discussing the same material yes. It does seem tough so for a hybrid it would ? I guess it is time to spend more $ then and test it
Assuming your chamber will reasonably seal, cut a 2" disk and tighten it in front of a male cam lock on your cannon.

Fire it at 1x and see if it bursts. If it doesn't burst, don't worry, your cannon won't explode...just a little out rush of warm air when you open your vent.

If you have a compressor and a psi gauge you can attach temporarily, you can do the same thing by filling it with air and watch the gauge until she pops.

Posted: Tue Feb 10, 2009 12:08 am
by trigun
i think i am goin to call myself your apprentice from now on ! After reading your triple thunder article i relized that it can contain explosions without blowing up. As for the hybrid it is a 1.5" union and i can just use the gun itself to test it then.

Posted: Tue Feb 10, 2009 2:13 am
by starman
trigun wrote:As for the hybrid it is a 1.5" union and i can just use the gun itself to test it then.
I wouldn't be as quick to be containing hybrid explosions, although a properly built hybrid should be able to do it....just gives me the hebee jebees thinking about it... 8)

It will be much safer to do compressed air tests with layers of material. That way you can roughly extrapolate a per layer burst level and therefore high pressure levels for your particular opening.

Humm..apprentice huhhh. I hope you're willing to work for peanuts.... :wink:

Re: New burst disk idea ?

Posted: Tue Feb 10, 2009 1:34 pm
by jimmy101
trigun wrote:I was at home depot the other day and saw they sold pvc sheet. It is fairly thin so it seems like a good burst disk. Has anyone else ever tried to use this material?
I've never seen sheet PVC at Home Depot. What section was it in and how thick is it?

Some Home Depots have PVC moldings used for exterior home trim. Sometimes they have a useable shape, like 4"x0.75"xmany feet long. Great stuff for gun mounts, tripods etc. though kind of expensive.

Posted: Tue Feb 10, 2009 1:49 pm
by starman
He's talking about the PVC shower pan liner material. Here's an Oatey product example and is .040". Home Depot (at least my local one) offers it in bulk form from large 4' and 6' horizontal spools and sells it by the foot in the plumbing section.

Posted: Tue Feb 10, 2009 2:07 pm
by D_Hall
starman wrote:Because it's fairly thick, you aren't going to be able to use more than 1 layer at a time.
I'll bite.... Why not?

Posted: Tue Feb 10, 2009 2:13 pm
by starman
D_Hall wrote:
starman wrote:Because it's fairly thick, you aren't going to be able to use more than 1 layer at a time.
I'll bite.... Why not?
...while using his camlock...starts getting a little too thick to lock it down. A different burst disk holder design could be a different story.

Posted: Tue Feb 10, 2009 2:33 pm
by john bunsenburner
maybe the cut offs from pool constuction liners could be used as a cheeper alternative. I think it is nearly identical but cheeper as there should be left over parts (nearly) for free.

Posted: Tue Feb 10, 2009 10:21 pm
by D_Hall
starman wrote:...while using his camlock...starts getting a little too thick to lock it down. A different burst disk holder design could be a different story.
OK, I saw you speaking of a cam lock but didn't see him talking of such. I figured you were just suggesting a design but I now gather that you simply have knowledge of his design. Gotcha.

Posted: Tue Feb 10, 2009 10:26 pm
by trigun
He is speaking of my combustion cannon "Herminator" that uses camlocks

Posted: Tue Feb 10, 2009 10:35 pm
by starman
Yeah sorry for the confusion, I was thinking "Herminator" configuration while we were discussing this because that was his assumed cannon of record, at least on my part...before today that is... :?

Posted: Wed Feb 11, 2009 11:55 am
by psycix
D_hall wrote:I'll bite.... Why not?
Because burst disks with that burst pressure/diameter are usually made out of sheet metal; mostly because this will not be ridiculously thick and can be locked in easier.