I'm in the process of running copper line in my home shop for compressed air, and I'd like to hear what folks think of doing the same for welding gases.

I'm thinking probably 2 lines eventually - one 75/25, and one argon. Pressure regulator on the cylinder feeding the line, and flow regulator at the back of the welder. I have a couple work areas - one indoors, one outdoors, about 75' apart, where I'd plumb the gas and electrical hookups.

Thinking being, I'll eat the up-front cost for 300cf cylinders to be cheaper in the long run, but they need to stay in one spot. Copper line means I don't need to drag hose around, I don't need to waste a lot of gas priming the line each time I setup, and the welding cart is loads lighter. (Maybe my math is off, but it looks like it'd take at least 13cf just to prime a 100' 1/4" hose - much more depending on the pressure.)

If this isn't too crazy, then what's a good line size to run? Wading through the online calculators, it looks like 1/4" i.d. line could handle up to about 30cfh - but is that too tight? I'm reluctant to oversize the piping because it'll bleed off when the tank is closed and waste more gas to recharge the line at next use.

Cheers,
Richard