Dear Olin Perry Norton:
"Olin Perry Norton" wrote in message news:dt593v$9kh$ snipped-for-privacy@nntp.msstate.edu... ...
I'd shoot for laminar flow (Re near 2000), if the purpose was to keep the lines clear. (Or short bursts of turbulent, with "signal hold" on the reading.) You could calibrate against static pressure to get the flow-induced drop, and factor it out.
David A. Smith
But if you're looking for a sensor that will measure VERY small air pressure differences, there is an almost no-cost method.
Two paint cans, half filled with water. Capped off. Stub pipes at the top run to the sensing points.
Two pipes at the foot of the two cans connecting them together. A thick pipe, with a stop-c*ck half way across.. The other, a thin pipe with a transparent wall - like glass.
Open the stop c*ck to level the fluid in the cans. Ensure there is an air bubble in the thin pipe. Close the stop-c*ck. A 0.001 inch WG difference to the two cans (if they are say 6 inch diameter) would move the bubble 2.3 inches sidewards if the sight pipe is 1/8 inch diameter!
Brian Whatcott Altus OK
That sounds like a neat trick. I'll try it next time I need to measure a very small delta P. It would be a good way to check the calibration of an electronic pressure transducer.
Thanks, Olin Perry Norton
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