I ran a CNC plasma table for a while. MAKE SURE the air is clean AND DRY before going to the plasma. It makes a HUGE difference.
Run the air like this:
Compressor to a Dryer to a filter at each drop before hooking it up to any tools. For painting, I would add a second filter at the drop used for painting. Try to use the same hose for painting and not anything else if possible. Clean dry air is important for painting.
Air tools need lubrication, I add a couple of drops every time I use mine directly into the coupler on the tool. If I don't think I am going to use the tool a good while, I put a couple drops in a shoot a short burst of air thru before I put it away.
Here is a diagram of what I am talking about....
http://www.gison.com.tw/Templates/pic/air-system.jpg