I have and I'll stick with 175psi as the machine was designed for.....
That is the max pressure it was designed for. It will operate more efficiently than a single stage at any pressure. A three stage is even more efficient but anything above that generally loses efficiency due to friction. A two stage is just more power efficient to only compress the air to the pressure you need for the job. Regulators waste the energy used to compress the air to the higher pressure. Sometimes regulators are required for certain processes. Air power is very inefficient to begin with.
Just so I'm clear, The reason against plastic in a home/hobby shop setup is because the plastic wont absorb/disperse enough heat to help in drying the compressed air. Right? So no one is arguing that the plastic (the stuff built for air! not PVC!) wont or cant be used for the reason it was intended or marketed. Just that home shops need all the help they can get as far as water separation goes.
Partially right.
The home shop may need all the help it can get with water separation. Infrequent air use and dry climates can help with that problem. Infrequent air use means the receiver can do most of the air cooling. The plastic tubing will not take the heat produced by the compressor during extended run cycles. Normally a run of metal pipe is used for the first 40' or so to avoid temperature problems. Plastic must also be supported well to avoid low spots that do collect water. Normally people just run it at extreme slopes to avoid that problem.
Plastic just really does not do anything right for an air distribution system. It is thermally deficient, usually size and volume deficient, and it is very susceptible to combustion heat which causes it to give way early and accelerate a fire before the fire alarms can give warning. Mechanical and fire codes vary so check with your local officials before use. However it IS easy to install. I started using Legris push fittings way back in the late 70's on machinery. They sure beat the hell out of compression fittings. I generally find it is easier overall to use the right stuff to begin with and avoid problems or replacement down the line. Especially when one gets hooked on air and gets more and more air toys.
