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[DPRG] Measuring Speed of sound in a liquid

Subject: [DPRG] Measuring Speed of sound in a liquid
From: Rick J. Bickle rbickle at swbell.net
Date: Fri Sep 3 10:18:16 CDT 2004

Kip,

Here are some links to manufacturers of sealed ultrasonic transducers.
One of them even shows microcontroller interface schematics.

http://www.hexamite.com/he240stxrx.htm

http://www.parsonicscorp.com/ultrasonics.html

Would a teflon sensor be inert in the chemicals?

Something else that comes to mind: If this is going to be done in a pipe
with moving liquid, will the liquid have air bubbles in it? If so, you
might be able to add a parallel pipe with solenoid valves at either end
to take a sampling, let the bubbles settle out, and then take a reading.

Rick


-----Original Message-----
From: dprglist-bounces at dprg.org [mailto:dprglist-bounces at dprg.org] On
Behalf Of Kipton Moravec
Sent: Thursday, September 02, 2004 11:17 PM
To: Robert Jordan
Cc: DPRG List
Subject: RE: [DPRG] Measuring Speed of sound in a liquid


It is a way to tell the percentage of one chemical in another.  There
are a 
few ways, refractometer is one ($15K-$25K). The speed of sound through
the 
liquid is another. pH is another method but is not as accurate and the 
probes could contaminate the solution. Conductivity is a fourth option
but 
again it is not as accurate and the probes could contaminate the sample
by 
adding a metal to it.

It is to replace a system that currently uses titration.  Take a sample
add 
a reagent to it, then add another chemical until the color 
changes.  Problem is that it wastes an expensive chemical. (They are 
currently sampling only 1 time per hour to try to keep the expense
down.)

The problem is finding a membrane that will pass the high frequency
sound 
waves, but not interact to bases or acids.  See water is a problem with 
corrosion, but this environment is worse.  I do not know what frequency 
depth sounders use.

Kip

At 08:41 PM 9/2/04, you wrote:
>Kip,
>
>Why measure speed
>Are you looking to id what the liquid is or the purity or something? Or

>do you just need to measure the presence of liquid? A u-shaped fiber 
>optic will give you a "distressed Liquid" sensor with some accuracy or 
>transmittance, and somewhat inert to acids, etc.!
>Could you measure light to get the results, and use glass
>or crystal windowed pvc fittings?
>Brain storming.
>Bob
>
>-----Original Message-----
>From: dprglist-bounces at dprg.org [mailto:dprglist-bounces at dprg.org]On
>Behalf Of Kipton Moravec
>Sent: Thursday, September 02, 2004 4:38 PM
>To: DPRG List
>Subject: [DPRG] Measuring Speed of sound in a liquid
>
>
>I am looking for a way to measure the speed of sound through a liquid 
>in a PVC Pipe
>
>I am thinking of something like a PVC pipe with a T on each end so the 
>sound can have a straight shot from the transmitter to the receiver.
>
>                    Inlet                    Outlet
>                   _|  |______________|  |_
>Transmitter ____________________Reciever
>                              PVC Pipe
>So the issue is what to use for a membrane so the transmitter and 
>receiver do not get exposed to the liquid in the pipe (could be acidic 
>or caustic) PVC is good because not too much reacts with it.
>
>I am thinking I want to use a high frequency sound (40 kHz) and I 
>expect the sound will travel fastest through the PVC pipe unless it is 
>well damped.
>
>What do you think? Good idea or not? Is there a better way?  I want 
>about a meter between the transmitter and receiver to get the accuracy 
>I want.
>
>Kip
>
>_______________________________________________
>DPRGlist mailing list
>DPRGlist at dprg.org http://list.dprg.org/mailman/listinfo/dprglist


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