By the way, I worked for 15 years asembling ductwork, gas pipe and freon lines, water lines, so I decided I wasn't going to scimp when I was putting the air lines in for the pnuematics. I bought 1/2 inch galvenized pipe and fittings from Menards ( a large midwest chain)I used teflon pipe dope(the absolute best stuff) and guess what?
I had air leaks galore! The culprit? It seems to be the galvenized fittings that happened to say "China" on them!
This is why it pays to put unions in the piping every so often, so you can take apart and repair without starting all over again, taking it all apart!
My personal method of piping, I put a tee with a drip-leg(a nipple with a cap on it)hanging down every ten feet or so, this catches moisture and crud, every so often , when the air is turned off, pressure down, unscrew the caps and drain the line, this makes it all work longer without expensive filters, but if you have the money go with some filtering , keep the drip-legs though.
The longer the nipple in the drip-leg, the more capacity it has to capture crud and moisture.

"My Insanity is well-respected, until they wiggle free and become a stringer for a tabloid"