copper vs pvc compressor lines?

There's another option HDPE pipe. It's high density plastic and is certified as air lines depending on your needs. I'm an IT guy by profession but have a client that likes me to spec out almost anything for him. When he built a new building and needed to run lines for his dual air compressors to it, over 100 yards, and inside the building I came across this material. It works great. Not the cheapest but very nice stuff.

http://webcat.rhfs.com/familydetails.aspx?FamID=779