Newsgroups: comp.robotics,comp.dsp,sci.electronics
From: Mike@jkms.demon.co.uk (Mike Seabrook)
Path: cantaloupe.srv.cs.cmu.edu!das-news2.harvard.edu!news2.near.net!news.mathworks.com!news.alpha.net!uwm.edu!cs.utexas.edu!howland.reston.ans.net!news.sprintlink.net!peernews.demon.co.uk!jkms.demon.co.uk!Mike
Subject: Re: Measuring flowrate.. microwave?
References: <IHPLlKAjvEY5078yn@hsr.no>
Organization: Jordan Kent
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Date: Fri, 3 Mar 1995 10:09:45 +0000
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Xref: glinda.oz.cs.cmu.edu comp.robotics:18558 comp.dsp:17340 sci.electronics:122188

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.
>...

The comp.dsp answer is probably to find some fluid property that
varies enough with time to make a detectable "signature" of some
sort that persists for a little way down the tube.  Then measure the
property at two points a known distance apart and cross correlate
the results.  At good moments, this will tell you the velocity.  At
bad moments the signals will not correlate well enough to tell you
anything.  Be careful to distinguish good moments from bad moments.
The Christian Michelsen institute in your country did some work
cross-correlating local composition variations in oil/gas mixtures
that now forms part of a commercial product.

However, as your stuff is thick, single phase, and probably in
laminar flow I would hesitate to recommend this solution. 

Would it be too simple to use a little electric heater fed with
known power and measure the resulting temperature rise?  Brooks used
to do a flowmeter like this (mostly used in the semiconductor
industry) which would cope with the conditions you mention.  They
are now part of Rosemount or Fisher-Rosemount or whatever they call
themselves this week.  There is bound to be an office in Norway.

Or then again, you might get some good ideas from sci.mech.fluids

-- 
Mike Seabrook                                         mike@jkms.demon.co.uk
Jordan Kent, Gloucestershire, UK
