I run a fancy air system in my garage. The idea is great, but PVC water pipe would have been cheaper and better.
As it goes, I have my air compressor which is under my work bench. I flip a switch and it goes on. It is directly plumbed into a junction box next to my workbench. There, I have a gauge and a connection point. From there, the line goes up the wall to the ceiling. Then to an air reel. I'll be honest, that air reel is the shizzle. 99% of the time I'm using air, I'm using that. If you are going to be plumbing everything, GET ONE. I love mine. From there, the line then continues to the front of my garage to a terminating junction box with air chuck connection. I enjoy having an air connection at the very front of my garage. Makes filling a tire quick and easy, or running the air gun to blow off stuff outside, or whatever. Its on a coil hose.
One of our family friends uses PVC in their shop. But he has like, a real automotive repair shop. Apparently PVC pipe for water is rated for 200-something psi. So its fine for 125 psi. Its cheap and when it breaks, its easy to fix.
I say go that route. Or the route with my system. I think all told, it was like, $200 for hose, three junction boxes, and a crap load of fittings. Everything was plug n' play. Needed a few extra fittings, but a quick ride up to Lowes solved that problem.
Overall, NOT having an air hose on the ground is amazing.