newshound wrote:

On 23/02/2018 20:42, Cursitor Doom wrote:
Gentlemen,

Say I'm running an air tool off my compressor via a 20m long airline with
a 10mm internal diameter bore which connects, at the far end, to the tool
via a 10mm ID coupling. Let's say this arrangement is *just* sufficient
to run the tool at its full rated power. Now for whatever reason I change
the coupling to one with say a 7mm ID instead, with everything else
remaining unchanged. Will the tool's performance be negatively affected?
Common sense would seem to suggest so at first sight, but is that
actually the case?



To a first approximation, you reduce the area by a factor of 2, so the
flow rate by a factor of two, so the power by a factor of 2. I'd expect
you to notice a significant drop in performance.

My vague recollection is that flow resistance goes up a lot faster than
inversely to the square of the diameter. But I thought the OP was just
changing the diameter of one coupling, and I don't think this will make
much difference compared with the flow resistance of 20m of tubing.



--

Roger Hayter