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From: a0014246@unicorn.it.wsu.edu (mark fuller)
Subject: Re: Measuring flowrate.. microwave?
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References: <IHPLlKAjvEY5078yn@hsr.no> <794225385snz@jkms.demon.co.uk>
Date: Mon, 6 Mar 1995 10:14:02 GMT
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Xref: glinda.oz.cs.cmu.edu comp.robotics:18641 comp.dsp:17391 sci.electronics:122512

Mike Seabrook (Mike@jkms.demon.co.uk) wrote:
: In article <IHPLlKAjvEY5078yn@hsr.no> frank-h@hsr.no "Atle Andersen" writes:

: >...
: >So:  How can I measure flowrate when the pressure is max. 250bar?
: >The flow rate will be no more than 15ltr/min, and the viscosity of the paint
: >is 200 cps.  I've been looking into those $6,000+++ microwave devices, but -
: >ahem - the price is too stiff. Is there are way of making such a device in the
: >electronics hobby room? =)  I'm pretty comfortable with microcontrollers.

Two ways come to mind.
One is a heated probe flow meter.  It works by maintaining the probe at a 
temerature set above ambient.  The amount of current required to maintain \
this temperature is directly porportional to the rate that a fluid can 
carry away heat.
The other method pops into mind since you mentioned that the pressure hits 
fairly high pressures.  Piston pump maybe?  If so, just count strokes over
 time.  With a constant volume per stroke, it should be ver accurate.
If a shorter time constant is needed, you can measure the actual position
of the stroke.  Costs a bit more to add a linear potentionmeter or a LVDT.
But this method would be extremely accurate.

Mark Fuller
TANSTAAFL
