When I worked at a lab, instead of having canned air for everyone, the owner had a HUGE air compressor at the end of the hallways. He then ran a line to each printing room with a squeezing thing. This was for blowing air on the negs. Am thinking of doing something the same to my darkroom. Do you guys think a 2 HP air compressor is enough? The nozzle end was brass and a type of squeeze grip. I don't know much about air compressors and I do remember, that if everyone uses it all at once, you have to wait a couple of minutes to get the pressure back.