I am considering two options:
1) Using 6" PVC with Wyes and double 45 elbows. The pipe is cheap, but the fittings are expensive.
2) Using 8" steel for most of the system (dropping to PVC for individual machines), using Ts and 90 elbows. The pipe is expensive, but the fittings are cheap.
Seems to me, based on those engineering courses I vaguely remember taking 40 years ago, that an 8" T should be as good as a 6" Wye. Anyone strongly agree or disagree with that? Sure, 8" Wyes would be optimal, but they aren't available here, would be harder to lay out, and geez, how good does a system have to be to run single machines off 3hp?
Second question is whether I put in a T (or a Wye) where I think I might need one for future machines, or do I rebuild everything when it comes to that?