So this morning I was driving to pick up a car. ( I tow ) and My boss just got a 2006 International flatbed truck. It has air brakes and bags with a DUMP valve. So I was like. " Lets see how fast this bitch fills a 9 gallon tank" So I start dumping and refiling the damn bags and after 3 dumps I only had 80 psi. The truck was ideling and the copressor went on. It refiled the tank from 80 to 145 in less then 2 secs I mean WTF? How the fuck does that work? How big are those compressors?