PVC failure under air pressure is always catastrophic. Its why PVC is somewhat disliked by more than a few folk for our stuff. With that said, 2" sched80 in new condition that hasnt been compromised.. I think should hold well past 150psi, which is the upper limit, by rule of every club (I think some may be lower actually), of the low pressure sides of our systems. But...
Way back in the freon days some one had a freon tank blow in there ship. I have heard it was just like a real magazine explosion. Stuff falling ou of the sky into the water, smoke, the hull slipping under the water. No photos or video, bummer.
We use the pvc accumulators here, and personally, I'd rather have a 200 psi explosion from a pvc accumulator than a 800psi explosion from a metal one. It's all about planning where and how your system fails...I actually have two hose joints onboard my ship where I dont use the metal rings to hold the hose onto the barb. If something goes wrong, and an overpressure occurs, the hose blows off and the system vents. I delclare myself sunk and then spend a while getting my frozen tank unstuck from the inside of my ship.
I use the hose-as-safety-device trick as well. I disagree that using a metal accumulator is asking for an 800psi explosion, as it's pretty rare for our regulators to run that high (never heard of one doing it, anyhow), and the hoses would burst well before that point, metal clamps or no.
A copper accumulator failing at 800 psi may even be safer than a PVC accumulator failing at 200 psi, so it really depends on the metal you use. PVC frags when it fails, copper would rupture but not send frags flying. Sure 800 psi would be a bigger bang and more underwear might need changing but there would be less chance of bloody wounds. That said use ABS, if you want to use plastic, it doesnt frag when it fails.
