If you've ever been to the dentist, you've probably been pretty close to pneumatic logic. Every delivery unit I've seen has used it. (Power a handpiece only if it's not in its holster, spray water only when the water switch is on and the handpiece is turning, etc.) Fixing them is a pain. You have to have just the right rubber sheets, gaskets, o-rings, etc. Also they're just a block of metal with a bunch of hoses attached. It's impossible figure out what an individual valve does just by looking at it.