Electromagnetic vs Ultrasonic Flowmeter: When to Use Which?

The main consideration for using electro-magnetic flowmeters (AKA magflow) is the conductivity of the fluid. If it has poor conductivity, magflow is not a choice. The pipe also needs to be completely filled. Magflow, however, has less stringent requirements for upstream and downstream piping and is more forgiving of having sediments or particulates in the fluid stream.

Some ultrasonic flowmeters need particles in the fluid that it can create the Doppler effect. More advanced ultrasonics are able to measure flow with clean fluids so be sure to read the documentation before purchasing. Ultrasonic signals are also affected by temperature so choose an instrument with temperature compensation.

If your process fluid creates coating on the walls of pipes, magflow that have teflon linings are better able to handle these situations. A teflon lined pipe (at the time when I was still working) is not suitable for ultrasonic flowmeters.

I don't usually rely on general comparisons, however. I read the technical documentation from the manufacturers or talk to one of their engineers to get information.

regards,

Vulcan