Hi Tom,

: At the school that i work at there is an old kellog american 1 1/2 horse
: compressor in the wood shop. It is a rather large unit probably about 4 ft
: long and 3 or so high. I was wondering if this compressor would push a D/A
: sander? I know they take a lot of cfm but i don't know how to find out how
: much this compressor puts out.

I have worked with this size of compressor before and they are not sufficient to run a random orbital sander continuously for any length of time.

The rule of thumb is that, if you have only one person working in a shop, you should buy a compressor that is adequate for the highest drawing tool in the shop. This is invariably the paint guns. They need a large amount of air and they need it continually with no pressure fluctuations. A regular siphon feed spray gun will require a 5 horse compressor (3 hp. if you are only spraying small items which will allow the compressor to catch up between coats) If more people work in a shop then you must add up the numbers for the highset drawing tool combination and get the correct compressor. If you are only using the random orbital sander all you need to do is check what it requires and get a compressor that will supply it without working too hard.

I haven't worked in a shop with less than a 25 hp. compressor in a long time. Right now we have a 25 hp. and with 3 bodymen, a prepper and a painter I can feel a pressure drop (poor tool performance) when we are in full production.

An interesting little note- I did my training in a shop that had a compressor that could pump 140 psi. out of a 4 inch diameter pipe, continuously. It supplied 6 training shops with all the air they reqired. The air was run through a $50,000.00 refridgerated air drier before it went into the shops. It was quite a set up.

Ian