Hi Barney,
Thanks for the info, and thanks especially for the link. It was very
informative. I smiled when I saw who wrote it :-)
One of the big reasons for the air compressor is sandblasting. I will go
check out the sandblasters for CFM.
I'm looking at Ingersole Rand and Campbell-Hausfield. They have twin
cylinder compressors, but I assume single stage because they don't state
it one way or the other -- 240V only -- I was aware of the amperage
thing with 120V.
So it sounds dual stage is not important unless I want to build the
compress and fit it with a smaller motor. The motor that comes with the
compressor will turn the pump at a set speed and I get the rated CFM no
matter what: single stage or dual stage.
Thanks again. I appreciate the help.
I hope you guys appreciate how important all this information is. My
TR250 and MGB have sat in the garage for a long time because I didn't
know what to do -- how to restore them -- and I didn't have the time to
do it.
The internet and these message boards have solved one problem -- I know
where to go to find the answers. Now I just need the time.
Thanks again
Don Malling
Barney Gaylord wrote:
>
> At 12:31 AM 10/5/02 -0400, you wrote:
> >If I can get the CFM I think I need (11 to 18 CFM or so) from an 80 gallon
> >single stage air compressor, why would a two stage be better -- what are
> >the advantages of a two stage over a single stage, assuming the same CFM
> >from both.
>
> Two stage is more efficient, can run the same volume with a smaller motor.
>
> >Is 11 CFM generally sufficient, or should do I need more like maybe 18.
>
> For a hopme shop, 8 to 9 CFM at 40 PSI or 7 CFM at 90 PSI is generally
> sufficient, and can be had from a much smaller unit.
>
> >I see some air tools need more. A $39.00 air nibbler at Harbor Freight
> >uses 4 CFM and a $29.00 nibbler uses 14 CFM -- a lot more. Do the cheaper
> >air tools tend to use more CFM?
>
> Nope. Cheaper tools often have smaller air motors, use less air, have less
> power. If the unit needs 14 CFM it will also need a VERY LARGE AIR
> HOSE. The 14 CFM nibbler does not need a 14 CFM compressor. It will run
> quit happily on a 7 CFM compressor, but with only 50% duty cycle, neaming
> you might operate the tool for 30 seconds out of any 1 minute is the
> compressor has a small air tank, or maybe 2 minutes continuous out of a 4
> minute period if the tank is larger. The tool draws air from the tank, and
> as long as the tank has sufficient pressure whenever it is demanded, the
> tool could care less what kind of compressor is supplying the air.
>
> Please read this: http://www.ntsource.com/~barneymg/mgtech/tools/compress.htm
>
> Regards,
>
> Barney Gaylord
> 1958 MGA with an attitude
> http://www.ntsource.com/~barneymg
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