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Re: Air compressors

To: Barney Gaylord <webmaster@chicagolandmgclub.com>,
Subject: Re: Air compressors
From: Don Malling <dmallin@attglobal.net>
Date: Sat, 05 Oct 2002 18:54:46 -0400
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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