Absolutely do not use any kind of PVC for compressed air. PVC becomes brittle overtime and is prone to burst under air pressure. I know it is tempting because it is easy to assemble and cheap to buy, but you are tempting fate if you use it. Without getting into the professional air lines that are excellent but very expensive, there are two acceptable media that you can use. Black iron and copper. My personal choice is copper because it does not rust and is much easier to install. Copper assembles like PVC except joints are soldered rather than being solvent welded. Black iron will rust and while probably not rust to the point of leaking air for many years, it will produce some rust inside that could contaminate tools, especially paint guns.