SpudFiles

the sealing face on my new piston valve keeps blowing out at about 40 psi. it does not ruin the rubber washer, i just have to push the piston back and then the washer lays flat again. has any one else had this problem?

You could take a metal washer that is slightly smaller than the barrel that you want to seal and place it in front of the rubber washer.

A picture of your piston would be nice.

What size piston?

If it's too small to bolt the sealing face on or use a screw (i.e, you have a small barrel about 10mm in diameter or under), you'll have to use super glue or epoxy.

If you can bolt or screw the sealing face on, do that. Make sure you have a metal washer on the sealing face going through the bolt to hold the sealing face on like described above. You may need quite a big metal washer as sealing faces have a tendancy to get ripped off around a metal washer if it's too small. You could try gluing and epoxying it also.

I agree with the above, but be aware that my pneumatic works well with a sealing face consisting of rubber layered with some kind of fibers. I drilled an undersize hole, and the bolt head is rather large, so it works fine at high pressures (>400psi)

Using a thicker rubber sealing face with the above works well to prevent excessive bending of the face.

i got a metal washer that is just smaller than the barrel and it seems to work fine now. now i just have to give it a name and post it.