I wouldn't think PVC would be safe for Higher pressures
PVC has high enough pressure ratings for compressed air, that's not were the problems arise.
The problems are the heat, vibration, breakage from a sudden shock, and chemical breakdown, due to contaminates in the compressed air.
I once worked in a Body shop with PVC airlines, and saw the problems first hand.
I have seen pipes break. But, I have not seen any shatter as has been reported.
Some simple research will turn up many documented cases of accidents involving PVC pipe and compressed air. There is no question it has been proven to be dangerous.
The analogy that you can repeatedly cross the street without looking, and not get hurt, that does not mean it is safe, was once made here about using PVC pipe for air lines.
I would not use it at all. But, if you want to limit the risk, use it with the stipulations I made in my previous post. They were all done as a result of failures, and did eliminate those problems.
Using PVC pipe is, just like crossing the street without looking.