I have two older (pre-screamer) traditional Craftsman compressors. I have
them connected in tandem so I will have higher volume when I use the
sandblaster or other tools that need higher volume at high pressure.

I don't use any check valves at all. The compressors each have their own,
between the tank and the compressor outlet port.

My shop is over 100 feet long, between my machine shop and an automotive
work area on the other end. I put a compressor at each end and my air line
(pvc pipe) runs the length of the shop with a tees and two QC outlets every
10 ft. There is also a dirt and water trap at each outlet station.

I have one compressor set at the max pressure cut off and the second set a
few lbs lower so the second seldom starts and if it does, it is not at the
same time (both compressors are on the same circuit breaker so I can turn
them both off when I leave the shop.)

I have been warned by others, that PVC is not a good idea, but since my shop
is so long, I needed a cheap method and so far I have not experienced an
problems. We will
see if there is when the weather gets well below freezing. The only problem
area I can see is in the water traps at each QD tee.

--
My experience and opinion, FWIW

(the other) Steve