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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: Thu Sep 2 17:16:00 CDT 2004


How about a sealed ultrasonic sensor at one end of the pipe. Give it a
short pulse, and then measure the time to the reflected pulse.
Calculated against a known distance to the reflector, this should
provide a good speed measurement. If the goal is to determine the
density of liquid, then you should also have temperature sensors in the
pipe, and an algorithm or table of density figures for the liquid in

I used to do some of this for fuel volume measurements.


-----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
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
do not get exposed to the liquid in the pipe (could be acidic or
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

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.


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