Here, a ten-fold (one order of magnitude) change in liquid resistance barely affects the measured
voltage (49.995 mV versus 49.95 mV) because the flow transmitter’s voltage-sensing electronic circuit
has such a high input impedance. The liquid’s equivalent resistance value must increase dramatically
beyond the values shown in this example before it will have any significant effect on flow measurement
accuracy.
In fact, the only time fluid conductivity is a problem with magnetic flowmeters is when the
fluid in question has negligible conductivity. Such fluids include deionized water (e.g. steam boiler
feedwater, ultrapure water for pharmaceutical and semiconductor manufacturing) and oils. Most
aqueous (water-based) fluids work fine with magnetic flowmeters