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rbuti
Joined: 17 Jun 2008
Posts: 1
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 17 Jun 2008 19:34 density meter for liquid |
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Does any one know a valid reference design or documentation to start a design of a density meter for liquid ? (in line meter system)
i hear something based on frequency resonance or coriolis effect, again something on magnetc reluctance , but i don't find material except commercial products.
Thanks
Roberto
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Sinisa
Joined: 03 Mar 2003
Posts: 260
Helped: 49
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| 19 Jun 2008 20:05 Re: density meter for liquid |
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Archimedes invented that long time ago. Something about him running naked and yelling "Eureka".
Coriolis effect, magnetic reluctance? How is that going to tell you density?
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FvM
Joined: 22 Jan 2008
Posts: 2476
Helped: 408
Location: Bochum, Germany
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| 19 Jun 2008 20:31 Re: density meter for liquid |
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Reference design may be asking somewhat too much. To identify a suitable sensor principle would be quite a lot to my opinion.
Most industrial density measurement systems are based on sensing the acceleration force or oscillation frequency with oscillations of the analysed media. The remaining is bases on hydrometer or scale.
To advance with a design, you should first define your accuracy and resolution requirements.
P.S.: Thanks to Sinisa for illustrating hydrometer operation! Coriolis principle is related to desnity measurement in so far, that coriolis mass flow meters are additionally measuring the fluid density, but it's not a favourite principle for pure density measurement. Magnetic reluctance? Perhaps to detect a hydrometer position or monitor displacement with an oscillating sensor.
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kender
Joined: 19 Jun 2005
Posts: 931
Helped: 68
Location: Stanford, SF Bay Peninsula, California, Earth, Solar System, Milky Way
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| 20 Jun 2008 23:11 Re: density meter for liquid |
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Hi Roberto,
The inline density meters that I saw were measuring the speed of sound in the fluid and estimating the density from it. So, I guess, I don't have an answer to your question. However, I'd like to invite your question to a specialized group dedicated to sensors: http://tech.groups.yahoo.com/group/sensorforum
Regards,
- Nick
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FvM
Joined: 22 Jan 2008
Posts: 2476
Helped: 408
Location: Bochum, Germany
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| 21 Jun 2008 12:50 Re: density meter for liquid |
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| The fact, that water and mercury have nearly identical sound velocity (around 1450 m/s) clarifies, that this sensor principle isn't applicable generally. Basically, sound velocity in a fluid is a function of density and compressibility. That means, that density can be determined from sound velocity only for a known binary mixture, e. g. water/ethanol.
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