Another shop air question

Copper water tube is an excellent choice for "normal" compressed air lines. "Normal" in this case means the common pressures of 175 psig or less seen in most shop compressed air systems and sizes one inch and less. Type L and type M are the common strengths that you find being used in plumbing and heating systems. Either is sufficient for compressed air, although the type L is a little heavier wall and would provide a better resistance to physical abuse. The issue with copper tube is the joints. The solder joints are the weak link in the system. The type of solder used determines the safe working pressure. The 50/50 tin-lead will work OK if you are positive the working temperature will always be 100-150 deg F or less. The 95/5 tin-antinomy is a much better choice to cover the possibility of higher temps. Even then, you should not use soldered joints of any kind between the compressor head and the tank. The temperatures are too high in that area. Sil-brazing or preferably fully mechanical joints would be the choice there. In fact, all the packaged compressors I have seen have copper w/mechanical joints between the compressor head and the storage tank.

I prefer copper because there are no corrosion products and it has a better heat transfer characteristic. It is also easy to install if one is reasonably proficient in soldering joints. The advantage of sched 40 steel pipe is that it provides significantly more protection from direct physical abuse than copper does. But you also have the threaded joints to deal with. I don't like messing with threaded joints, but that's just me. For most home-type shops the physical abuse issue is not likely a major consideration. Just stay away from PVC. That stuff is a serious safety hazard when used with compressed air. In fact, it is illegal in some areas (at least in commercial settings).

Rod

Who cares? - it"s your basement.

Charles