Electromagnetic flowmeters play a large role in many wastewater plants. ABB’S 90-in. MagMaster electromagnetic flowmeters measure the effluent from the new $45-million pump station at the Southerly Wastewater Treatment Plant in Columbus, Ohio. The two meters each have the capacity to measure 225 million gal per day. The piping configuration provides for adding a third 90-in. magmeter in the future.
Faraday’s law says that a conductor moving through a magnetic field produces an electric signal. In this case the fluid is the conductor and electromagnetic coils surrounding the meter body generate the magnetic field. Two electrodes embedded on opposite sides of the flow tube pick up the signal.
Magmeters have no moving parts. They offer high accuracies and wide range ability, as well as an unobstructed flow path, according to ABB. They are ideal for wastewater slurries. Magmeters require minimum lengths of straight pipe to condition the flow profile.
Magmeters from ABB can be calibrated in place and while in operation. This capability aims to generate significant savings compared to removing large meters for shipping back to the factory for recalibration. To check calibration, the service technician connects a verification tool to the magmeter. The tool verifies the meter's calibration to within ±1%. It compares test parameters to the meter's original "fingerprint," first determined at the factory following manufacture (and stored in the transmitter). The procedure offers traceability to NIST calibration with a printed certificate.
Source: ABB
