Electromagnetic Flowmeters

Electromagnetic Flowmeters

Electromagnetic (mag) flowmeters measure volumetric flow of electrically conductive liquids using Faraday’s law of induction. A magnetic field is generated across the meter bore; as charged particles in the fluid cross that field, a voltage is induced that is proportional to flow velocity and is detected by electrodes. With a known pipe cross-section, the instrument converts velocity to volumetric flow without introducing a restriction in the line.

Because the measuring principle is largely independent of pressure, density, temperature, and viscosity, mag meters are well suited for variable process conditions and for fluids that are difficult to characterize. A pulsed magnetic field with alternating polarity supports a stable zero point and helps keep measurement robust in inhomogeneous or multiphase liquids and lower-conductivity services. The open, unobstructed bore also eliminates wear components, keeping maintenance low and supporting clean-in-place, sterilize-in-place, or pigging strategies where the piping design allows.

Mag flow technology is a standard choice for water and wastewater, chemical processing, mining and minerals, and pulp and paper - especially where entrained solids are present. Endress+Hauser notes that even fluids with entrained solids (for example ore slurry or cellulose pulp) can be metered, provided liner and electrode materials are selected for abrasion and corrosion. Typical applications include raw water intake, distribution networks, effluent discharge, chemical dosing, and process transfer lines.

Performance is driven by conductivity, grounding, and maintaining a full pipe. Requirements such as minimum conductivity, avoidance of air pockets, proper electrode orientation, and stable grounding/bonding should be addressed early to reduce noise and drift. With designs spanning very small to very large nominal diameters (up to multi-meter transmission mains), electromagnetic metering scales from skid-mounted utility headers to large plant and municipal networks.

Selection generally focuses on accuracy requirements, liner/electrode compatibility, installation constraints, and diagnostics for asset management. When the process liquid is conductive and the line can be kept full, electromagnetic measurement delivers dependable volumetric flow with low lifecycle cost and strong immunity to changing fluid properties.

Miller Mechanical Specialties, an exclusive authorized representative of sales and service for Endress+Hauser.