Electrodes liquid contact electromagnetic flow meter?

[thomas49th]

Hello,

I'm interested in building a small non-invasive battery powered device that wraps around a pressured 1/2" pipe for measuring potable water.

From https://en.wikipedia.org/wiki/Magnetic_flow_meter
and watching youtube videos, it seems they all use electrodes which contact the liquid (water in my case) to measure the potential difference generated, hence making this an invasive technique. I was wondering if it's possible to just have the electrodes sit outside the pipe and still pick up the electric field?

I'm going to be measured flow rates of 0.1 to 20 litres per minute. Quite low.

If not what are my realistic options? Is ultrasound the only real way to go?

Thanks a lot!

 

[anorlunda]

Both magnetic and ultrasonic flow measurements are hard for do,it yourself and commercial units are expensive.

I think that your best choice is to go invasive with a propeller in the stream and a magnetic sensor pickup.

 

[Harvati]

Hi,

This thread caught my attention and join PF.

I recently came across https://twitter.com/MyFlowLabs/status/654773131693789184

Apparently it is retrofit (non-invasive). Unsure how they have achieved it, what technology they use and accuracy. It looks 3D printed? so maybe it's a doable hobby project.

Are takers on if they use ultrasonics, or something else? The form factor is small from other ultrasonic systems I've seen.

H.