New Valve (The Layman's Valve)

PhoenixFire · Posted: 05/04/2005 7:00 AM Post subject:

Here's my design for a piston type valve with a minimum of modification. I've got it built and it works, although not below 30 P.S.I. This could probably be remedied by improving the seal between the rear coupling and the 2 in. pipe.
!!!NOTE!!!
I built this thing around a wye which normally is only used for drain pipe and is not rated. You could replace the wye with a T if you cannot find a pressure rated wye.

The main reason i like this valve is that I don't need to mess with any rubber seals, the pvc bushing/coupling hold air perfectly. I also think it looks sweet.

Please note that the rear 1.25 in. coupling has been wrapped with aluminum tape to ensure a minimum loss of pressure.

If you DO have access toa lathe, go ahead and add some O-rings to the rear 1.25 in. coupling. This will ensure that only the air in the exhaust cavity is lost due to triggering the valve and no unneeded air leaks around the coupling from the main pressure chamber.

Here's some images of the parts & firing sequence.

Assembly should be apparent except for a few slightly modified fittings.

Some bushings need to be shaved so that the pipe can be passed through.

Also you should modify the the 1.25 in. coupling, and the 1.25 in. - 0.5 in. bushing to make sure that they slide together easily.

This valve works great for me. The only problem is that it wastes a lot of air to trigger the valve. I don't mind because I have a sweet little air compressor.
One might also ask why the hell I built all this to bump up the valve size from one inch to 1.25 inchs. I really don't know, but it looks pretty so lets just leave it at that. It should also be scaleable to larger sizes, but keep in mind that a 3 inch piston charged to 50 psi will be sucked back with 353 LBS and you'll need to implement some sort of buffer in the rear of the exhaust pipe. Even with this 2 inch pipe there's 157 LBS pulling it back.