Help getting flange seal to seal

[piercho]

I built a Ca Rx and cant get the flange seal to seal. My test setup pressurizes the vessel to 5 psi. When I soap the perimeter of the flange, I'm getting bubbles in several places.

Pipe diameter: 6"
Flange: 9"
o-ring groove diameter: 7 3/8"
o-ring groove width: 1/8"
o-ring groove depth: not sure, o-ring sits slightly higher so must be compressed when the flange is tightened down.
o-ring material: window-screen gasket, which is ridged, not smooth
bolt holes: 8
bolt hole diameter (bolt to bolt): 8 1/8"

I flush cut the o-ring as I couldn't get an angled splice cut to come out - the material wanted to twist as I layed it in the groove and the two ends would not match up. I then laid the o-ring down into a thin bed of silicone in the groove, and used silicone to join the two ends. The joint is fairly smooth, you'd think the compression when I tighten down the bolts would take care of it. Also, I'm getting bubbles from several point on the perimeter so I don't think the o-ring joint, by itself, is the problem. I have heard of other people getting 35 psi out of a window-screen-gasket 0-ring and I just bought the only brand of gasket that they had at Lowe's. I'm pretty sure that the problem is air traveling over the top of the seal.

Do I just need to use a different brand window screen gasket? Is there a smooth brand vice ridged?

If not, where can I get long lengths of 1/8" EDPM (or other rubber) gasket? Can I just use super glue to join the rubber?

Re-machining the groove is not an option at this point. Thanks for any help comments, and suggestions.

 

[DonW]

Window screen retaining rubber usually will not seal. I also dont think you need that much holding pressure. Use what ever pump you intend to feed the reactor with and close off the output. This will tell you if its tight enough, just incase the outlet were to plug up.

Don

 

[piercho]

The test engineer in me demands some sort of test... 5 psi seems like a pretty low pressure.

I've seen EDPM o-ring material at Harbor Freight for pretty cheap. But it comes in a set with no details if there is 1/8" material, or how long it is.

 

[DonW]

I buy O ring material at Mcclendons (sp?) hardware. Testing is fine but shouldnt the test medium be similar (beer/water co2/air).

Don

 

[fade2black]

Try getting Buna-N O-ring material, preferrably 3/16" thick. It is made for sealing (unlike window screen gasket) and makes a good seal with minimal pressure.

www.mcmaster.com, search for o-ring.