Almost nothing uses more air than a sandblaster. At least, the larger units.
This site rates them at 6-25 CFM. Which is quite a range...
http://www.sjdiscounttools.com/clasb9008.html
I'd lean more toward the 25CFM than the 6CFM end of the spectrum. From what I've experienced, a large 80-gallon upright compressor that puts out 13-19 or so CFM @ 90 PSI won't keep up with your average blast cabinet. You run it for about 3 minutes, let it refill for 5, and repeat. The compressor runs full-tilt the whole time, but unless you're cleaning the entire frame or engine block of a vehicle (or using it several times a day in a shop) that's okay. You can clean a lot of engine accesory brackets and valve covers in 3 minutes.
A buddy of mine's setup is what I"m basing that on. He had a shelf right next to the compressor on the wall, and sat a box fan right next to the pump/motor when he ran it for a long time to keep the heat down. Made a big difference in operating temps.
However, I've never even seen one of these units in person, so I dunno how it compares to your average cabinet type media blaster.
