ABSTRACT
Magnetic-type flowmeters use Faraday’s Law of electromagnetic induction for making a flow measurement. Faraday’s Law states that when a conductor moves through a magnetic field of given field strength, a voltage level is produced in the conductor that is dependent on the relative velocity between the conductor and the field. The magnetic flowmeter detects the volumetric flow rate by sensing the linear velocity of the liquid. The Equation of Continuity is the relationship which converts the velocity measurement to volumetric flow rate providing the area is constant. Therefore the area must be known and constant and the pipe must be full in order to obtain a correct measurement. Changing the method of excitation from line frequency (AC) to low frequency (DC) provided dramatic improvements in both the accuracy and the zero stability of magnetic flowmeters.
