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RE: Ray's Air Compressor thread

To: "John T. Blair" <>
Subject: RE: Ray's Air Compressor thread
From: "W. R. Gibbons" <>
Date: Thu, 12 Dec 1996 00:15:08 -0500 (EST)
On Wed, 11 Dec 1996, John T. Blair wrote:

> >Does the smallest diameter hose/pipe/fitting
> >that exists between the tank and the tool limit the
> >volume of air that reaches the blaster?

> IMHO, definetly.  The flow rate should be proportional to the
> cross sectional area of the hose.  The smaller the dia. the
> less flow.

I have to disagree.  The aggregate resistance between the compressor and 
the tool is what limits the flow, just as the total resistance in an 
electrical circuit limits the current.  If you have one small fitting, it 
contributes a certain resistance, but it is only part of the total.  As 
someone asked privately, if your tank fitting is 3/8, is there any point 
in putting an adapter on and going to a hose larger than 3/8.  There 
definitely is.  If you have one inch of 3/8 and 25 feet of 5/8, the 
resistance is way less than if you have 25 ft and one inch, all 3/8.  

All bets are off, however, if you go to extremes and say what if your one 
inch of fitting is 1/16th inch in diameter.  At some point, the 1/r to 
the fourth starts to kill you.


   Ray Gibbons  Dept. of Molecular Physiology & Biophysics
                Univ. of Vermont College of Medicine, Burlington, VT
        (802) 656-8910

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