Well if you get right down to it using washing machine valves, sprinkler valves ,etc. anything that is not designed for a pnuematic application is not really a wise way to go. Sure it is cheaper, but what is the cost of being safe? I'm not trying to preach, just sharing an experience that I had with PVC so hopefully no one would have it happen t othem.
Everyone has to believe in something, I believe I'll have another beer!