2" Union Burst Disks

[whoa044]

I was wondering, since I never got the opportunity to test out a soda can cutout to see its bursting pressure, has anybody ever done so with a 2" union?

The new hybrid design will be a large 2" hybrid. I've heard that problems may arise when so many burst disks are required. It's been told you must grind the edges off the inside of a union to fit a gasket, and that it will make fitting so many soda can disks airtight.

The thickness of 10 pieces is 0.97 millimeters. Will such a gap in the union be overcome by simply torquing the union a little more? The predicted mixes I may achieve (depending on burst disks), will be anywhere from 5x to 20x.

[SpudBlaster15]

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[whoa044]

Do all unions have tapered faces? What's required is to make the inside surface level, and to have a gasket on both sides of the disk? Would it be safe to glue the gasket to the union? Thanks so far btw

[SpudBlaster15]

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[whoa044]

I ordered a 2" 2kpsi union from Murray Equipment Inc just a two days ago.

Would it be possible to just grind off the barrel side of the union, so the other tapered side holds the gasket? Or if both sides are grinded off, the pipe on the chamber side will hold the gasket inside the union.

[Crna Legija]

you could give them a call and ask if the union you ordered has tapered faces

[whoa044]

Or I could just wait a few days. If it isn't tapered, then I guess I'm all good, only need a rubber washer.

I'm thinking of buying a few 1/4 thick neoprene squares, and then cut disks out using an X-Acto knife. That just gave me a great idea:
Instead of using rubber to make seals in the union. Couldn't we use thick rubber to be the burst disk itself?

[Crna Legija]

rubber wouldn't burst very well, it would make a small hole in the middle and the heat from the mix will melt it away a bit more but it wont be very fast like say layered aluminium foil and rubber disks would be expensive

[whoa044]

Yeah, rubber splits, rather than just falling apart like thin metal.
Does anybody know where I can get 2" circular punches?

[Technician1002]

Yeah, rubber splits, rather than just falling apart like thin metal.
Does anybody know where I can get 2" circular punches?

Make one. Use a piece of iron pipe and cut a cutting edge on it. I launched a piece of conduit with a sharpened edge at a washing machine and it performed well. A washing machine is a little thicker than a pop can.

[whoa044]

Good idea. Shouldn't be any trouble, except making sure that that is matches the diameter of the union. I'm assuming you also use 2" unions?

[ramses]

He uses his QDV, which is a type of piston valve.

Measure the diameter inside of the area in the union where the BD will go, and find something round and metal at the hardware store with the same diameter.

[whoa044]

Yeah I figured that's what I would do. It seems tapered steel pipe will be easier (and a little more consistent) to make a sharpened edge

[whoa044]

So I finally got my forged steel fittings in the mail from MEI. The box weighed, by my guess, around 30 pounds. This included all 2" fittings: 2, 6" nipples. a tee, union, and three bushings.

I swear, that union was huge:


I can see how the inside is tapered, if anybody is interested, I have a short video showing how large the thing is, and what the insides look like.

[Gun Freak]

Holy hell! That thing is a monster. Good luck on the launcher, can't wait to see it!