DonS,
I know PVC is so tempting, affordable and easy to install, but it really has the potential to fragment just from cold air changes from outside temperatures. And as mentioned from other posters...it is a illegal
My first shop (commercial), years ago, was 90% PVC
The second was black iron pipe, and after 6 years developed scaling and rust even with adequate water traps and draining the compressor daily. I dealt with the down time and replaced sections as needed.
My third shop was all copper.
And my last and current shop is all copper. "L" and "k" pipe is legal, will pass inspection and once installed you can forget about any problems in the future. The last installation I did was from a diagram available from "Sharpe Manufacturing Company Shop air piping layout" found by Google search. It is excellent and I followed it almost exactly (except I used copper) and it has been my shop setup to date. The only difference in my case was I had to slit vinyl tubing around the copper to isolate it from the mounting to an all steel building.
I use IR 80 gallon and Porter Cable 60 gallon vertical compressors plumbed together, but use the IR exclusively as the smaller one is for emergency back up and wired separately. This way I still have 140 gallon volume.
Good luck, Mark