spud gun/T-shirt gun valve

[GeeTwo]

Originally Posted by fovea1959

ah. There's the answer. It's not that the valve is more likely to fail at 70PSI air than 70 PSI water, it's that *if* it fails, the damage is more catastrophic. makes sense.

ok, so I shouldn't use Schedule 40 PVC for the tank or anything "upstream" of the shooting valve, what *do* I use?

We're using mostly galvanized pipe; I think there are a couple of pieces of black iron in there, too. Here's a picture with the cowling off.

We're getting air from a scuba tank, using a regular scuba regulator to get down to about 170 psi. We then use a regulator similar to the FRC KoP regulators to bring it down below 60 psi (we typically shoot about 50 psi) and direct that to a cast iron accumulator (painted green, next to the scuba tank). I believe we then have 1-1/2" galvanized to the tee, and 1" galvanized to the 3/4" solenoid valves (you can only see the brass side here, right next to Leevi's hand; the solenoid is behind that). Then there's a 3/4" quick disconnect, some factory-terminated reinforced rubber hose, a black iron street elbow, and finally the first bit of PVC in the expansion to the barrel. We will likely be switching to all galvanized (apart from the tank, solenoid valve, and hose) for next year.

Another reason not to use PVC, as has been noted before, is its failure mode. It tends to break, whereas most metals and fiber/wire reinforced hoses will tear. Therefore, PVC and similar plastics are more likely to become shrapnel than one twisted and torn piece.