Sealing face leaking at pressures above 200psi

[A-98]

This is an erroneous double post, in the process of remembering how to contact a mod to remove it.

[Technician1002]

Soft becomes fluid at those pressures. The sealing face is most likely getting a peripheral squeeze from the chamber pressure and resulting in a smaller diameter which then leaks. A good washer on the barrel side that prevents the rubber from bulging into the barrel will go a long way to prevent this from happening. A thinner harder seal is recommended for higher pressure. Lap the surface to ensure an initial seal at low pressure. An adhesive to prevent any pressure from getting under the seal an causing a bulge into the barrel is also a possible fix. This leak could be along the threaded shaft of the piston. Did you take steps to seal this so air can not get through the piston?

On your fuzzy picture of the sealing face, use a washer small enough to fit inside the valve seat and only expose the outer circle of rubber for the seal.

[A-98]

Oh my. It appears this is a double post. When I originally posted, I got an error, and upon inspection didn't see that a post was created. Apparently I did not inspect close enough.

The actual thread is here.