leaky burst disc

[JDP12]

Hey all, i was pressure testing my hybrid for leaks today, but i noticed something bad- air was escaping past my soda can burst disk. I hadn't tightened the union very much, so i think that might be part of the problem. My union is orientated the same way as SB15's on his handheld rifle if that is a piece of information you need.

also, i was PMin SB15 and he recommended adding an aluminum washer after the burst disc for more clamping power. I was just wondeirng since i don't have access to large metal drill bits or a milling machine, and i don't want to spend $30+ for one bit that i'll never use again, if i could make that out of plexiglass? I think i should be able to, but i'm not sure. I think the combustion would be quick enough so that the plexiglass doesn't warp, but what do you guys think?

Thanks for your help with both of my questions

[SpudBlaster15]

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[DYI]

Using aluminum foil instead of soda can disks will probably be easier, as well as cheaper. In a 1.5" union, 32 layers of aluminum foil will usually survive 400-450 psi. In a 1" union, more than twice that. And with only a butyl rubber gasket they seal nearly perfectly, even at 400+ psi.

[JDP12]

hmm yea i just can't figure out why its not sealing, SB15, do you think its somethin to do with the union orientation?

UPDATE: K i tested it with aluminum foil and with the union flipped, still leaked. do you think adding that disk would help SB15?

[noname]

If you don't have a rubber washer in the union, it's obviously gonna leak. If you do have one, try getting another so you have one on each side of the disc.

[JDP12]

oh i want one on each side?

I have one on one side, but not on the other... Hmm i'll add a rubber piece to my 1/4" plexiglass washer im making.. I think 1/4" should hold up fairly well (plexiglass that is)

[SpudBlaster15]

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[spanerman]

^seconded, theres a oring and leather washer in mine....and its grinded flat which helps no end

[JDP12]

which helps no end? what do you mean by that

[noname]

The rubber washer should be on the chamber side of the burst disc, it's pretty much useless on the other side.

[spanerman]

which helps no end? what do you mean by that

sory (term used over here in uk) it means it helps alot

[BigGrib]

i used a cam lock right at the end of my chamber for an interchangeable barrel system and i unscrewed my barrel from the male cam lock, put a burst disk in the female and put the male in it and locked it down tight worked like a charm. cam locks are really easy to come by where i live and really cheap too (aluminum is even cheaper than poly cam locks) I would personally use that cam locks i think it would make replacing the burst disks easier after each shot.