Electromagnetic flowmeter is used to measure the volume flow of conductive liquid medium with conductivity greater than 5μs/cm. To know the fluid conductivity is important. The conductivity of gas, oil, and most organic liquids is much lower than 5uS/cm, and they are not conductive.
That’s the reason it can’t use the magnetic flowmeter to measure. The non-conductive fluids are not workable with a magnetic flow meter.