The electromagnetic flow meter consists of a sensor through which the measured liquid flows and an electronic unit where the low-level signal from the sensor is modified to a standardized form suitable for further processing in various industrial electronic devices.
The output signal is proportional to the volumetric flow rate of the measured liquid. The only factor limiting the application of electromagnetic flow meters is the requirement that the measured liquid shall be conductive and non-magnetic.
The electromagnetic flow meter can be designed either as an integral device or with the sensor separated from the associated electronic unit. In the former case, the electronic unit is fitted directly onto the sensor, in the latter case it is connected to the sensor by a remote cable.
The sensor design shall take into consideration the type of the measured liquid and its operational parameters. To facilitate fitting into the liquid piping, the sensor can be provided with end flanges or as a wafer style design.
The function of an electromagnetic flow meter is based on Faraday’s law of induction. The sensor consists of a non-magnetic and non-conductive tube with two embedded measuring electrodes. To create an alternating magnetic field, two coils are fitted onto the tube in parallel with the plane defined by the active parts of the measuring electrodes. If a conductive liquid flows across the magnetic field, a voltage will appear on the measuring electrodes proportional to the flow velocity and the conductor length.