It sounds like some ball valves at the hose reels might be the way to go. I'll definitely be running PVC for the underground segments. Fortunately I'm in western Oregon. Do we even have a frost line here?
PVC is NEVER recommended for compressed air even by the factories. It can fracture and possibly blow chunks all over. There is a PVC built especially for compressed air but you better have a water cooled check book when you buy fittings.
I cannot remember what the code is for Seattle. Commonly I believe it is 18" for frost. 200 feet use a ditchwitch and set deep as possible. Long as you are at it throw in a couple conduits for electrical and a water line. Try to slope pipe in direction of air travel to keep line drained as much as possible (JOKE you are of course on dead flat level ground). Plumb in a drain valve at end to occasionally blow water out. I would look into using PEX for this application OR a plastic tubing (polypropylene ??) pulled thru a conduit so if (WHEN ??) it fails all you have to do is pull in another chunk of tubing and NEVER have to dig again (only cause you designed for failure - Murphy and his danged law)
ASCO valve designed for purpose at 1/4 or 1/2 should be around 50 to 75. They will probably have water air and oil designation. Use ball valves as much as possible.
Dan Bentler
