Jon Elson wrote ...

... 3/4 Hp is just too small for serious air tool work...


No argument in the context being discussed. However....

I've got three air conditioner compressors (one known good, two
unknown). Couldn't tell you the sizes, but I'm thinking it doesn't
matter much because I also have a 500 gallon propane tank that I'm
thinking of marrying one of them to. Now I may have to let the sucker
rung a day & a half to get up to pressure, but I'm thinking it would
take a LOT of serious air tool use to see much of a pressure drop from
a tank that size. Noise isn't an issue, the nearest neighbor is 1/2
mile & I can put the beast beyond the shop which is 100 yards from the
house. Any thoughts other than to pressure test it from a good
distance?






It would be fine for an air brush or tire filling, but almost any
standard
air tool, like a die grinder, air paint sprayer, (very small) sand
blaster, air chisel,
etc. will use at least 6 CFM, and some will use a lot more. Unless you
want to wait
5 minutes out of every 6, you will soon be looking for a bigger compressor.
Forget HP, as some compressors sold for industrial use DON'T lie about it,
so it can't be used for comparisons. Just look at CFM at 90 PSI (don't
be foold by ratings
at 40 PSI, either.)

The other bad news is that the oilless compressors tend to be EXTREMELY
noisy,
and will drive you (or your neighbors) nuts! Oil filled compressors
generally
turn much slower, and some good ones can be rather quiet.

Jon