Electromagnetic flow meters have been around for years and are the automatic choice for certain water-based flow applications. Also known as ‘Mag’ or even ‘Mag Flux’ flow meters, they are manufactured in a wide range of sizes, from 2mm bore to over 3 metres in diameter. Manufacturing cost, and therefore selling prices, don’t drastically increase as the flowmeter size increases, making mag meters extremely cost-effective in the case of large bore installations.
Mag meters offer no obstruction to flow, making it the ideal choice when it comes to handling slurries, paper pulp, effluent and other conductive liquids with solids content. With no flow restriction, the electromagnetic flowmeter doesn’t increase system pressure which is great for gravity fed and low-pressure applications.
Mag meters require minimal straight pipe upstream and downstream, which makes installation much easier. It means that flow disturbances due to close proximity to bends or valves have only a marginal effect on measurement accuracy. Mag flow meters measure volumetrically and are practically unaffected by changes in liquid viscosity, density, temperature and pressure. They also have a very wide measuring range which often enables us to match flowmeter size to the process pipe line size where flow rates may be low or uncharacteristically high.
Another almost unique feature of a mag flowmeter is its ability to measure flow in either direction, forward and reverse. This advantage offers customers the ability to measure nett total (i.e. forward total minus reverse total).
Today’s electromagnetic flow meters offer a variety of signal outputs in addition to the usual 4-20mA and pulse/frequency, examples being HART, PROFIBUS, MODBUS, Bluetooth & Wifi. With such a wide choice of signal outputs, electromagnetic flowmeters can be installed in stand-alone single-loop systems as well as in more complex DCS networks. Output signals are linear to flow so there is no need for signal converters with mag meters.
Endress & Hauser offer electromagnetic flowmeters manufactured with a wide choice of liner and electrode materials which can be selected to suit specific application needs. In addition to the standard flanged process connections Endress and Hauser offer Mag meters with hygienic process connections tailored for the dairy and pharmaceutical sectors.
For more ways to measure liquid, head to our turbine flow meters and ultrasonic flow meters page.