measure liquid flow by a contactless clamp flow meter

[MisaghSepehr]

I want to measure liquid flow by a contactless clamp flow meter(It's my graduation project).in other words I should build a
cotactless clamp liquid flow measurement instrument.does any one have idea how can i do that?
I intended to measure it by electromagnetic technique but it needs two electrodes contacting fluid.
further,the pipe must be electrically insulator(beacause of principle theory of faraday's induction law).
This is a part of "Friedrich Hofmann"'s book text:
The signal voltage induced in the process liquid should not be short-circuited by electrically conductive tube walls.
I'll be grateful to recieve every suggestion and help.
Regards-Misagh

 

[penrico]

I suggest you can try ultrasound

 

[hakeen]

I think ultrasound too. It uses doppler effect. It is a good method for touchless flow measurement systems. As far as I know acoustic and laser are two ways of it. The former is comparitvely cheaper approach. ut you need to design a system with several receivers. The latter can be very fine solution, but expensive and depends also the tube conditons (transperency to wavelength etc.).

I guess a good start point might be

https://en.wikipedia.org/wiki/Flow_measurement

You can refer to text about doppler affects.

 

[penrico]

Other idea, that I don't know if it will work on liquids. But, it works for flow measuring of gases. It's the use of accellerometers in the pipe. The flow produces vibrations on the pipe, and it's proportional to the amount of gas inside or its speed.

 

[MisaghSepehr]

thanks for your reply.
let's discusse more about ultrasonic technique.
I guess: By ultrasonic technique,used pipe material will be important.Further,the fluid viscosity will significantly be effective on output measured frequency or transit time.
I'm right?
how can I compensate these effects?

 

[FvM]

Ultrasonic clamp on flowmeters are offered since decades by major manufaturers, see e.g. . For the handling of specific problems with clamp-on technique, you may want to consult respective manufacturer manuals and technical literature. I guess, they are also discussed in general measurement technique text books.

A key point of US flow meters is the acoustic impedance matching between transducer and medium. It's clearly worse with clamp-on, performance of clamp-on meters isn't as good as inline for this reason.

Other techniques aren't promising for true contactless operation, abovely mentioned EMF can't work, I think. Coriolis mass-flow, as mentioned by penrico, can basically work with straight tubes, but the requirements for the tube properties are very strict, and most-likely can't be fullfilled by an arbitrary process pipe.