Over the years the standard for plumbing compressed air has been black pipe. Yup, the black pipe creates all sorts of problems for the quality of the air, but it has been cheap, and it can certainly handle the air pressure for all but the highest outputs.
I’ve been a proponent of copper pipe for the DIY crowd, and I’d recommend it for institutional use as well, save for the cost.
One company has developed a line of plastic compressed air plumbing products, but it’s not recognized as suitable in many jurisdictions, and I, with a bit of background in plastics as well as compressed air, would want to be really convinced before I’d plumb compressed air through rigid plastic pipe.
Now there’s another alternative. It probably is a premium priced product, yet overall, with the ease of installation, maybe the installed cost is competitive? I’m talking about aluminum compressed air pipe, and you can read more about it here.
