What is a flowmeter and what is it used for
A flowmeter measures the quantity of liquid passing through a pipeline per unit of time, usually in m³/h or l/s, and totalises the volume that has passed. Flow data is the basis for dosing, consumption billing, pump control and leak detection, so flowmeters are found in water supply, treatment plants, the chemical and food industries and power generation.
How an electromagnetic flowmeter works
An electromagnetic flowmeter works on Faraday's law of induction. Coils in the sensor create a magnetic field across the pipe, and a conductive liquid flowing through this field induces a voltage proportional to its velocity. Electrodes pass this voltage to the transmitter, which converts it into flow. Because there are no moving parts or restrictions in the pipe, measurement causes no pressure loss, nothing wears out, and accuracy does not depend on the density, viscosity or temperature of the medium. The only requirement is a minimum conductivity of 5 µS/cm.
Products in the Fadip range
The PEM-500 electromagnetic flowmeter covers pipelines from DN 10 to DN 300 (ANSI 1/2" to 12"), with 0.5% accuracy, for static pressures of 16, 25 or 40 bar. The PEM-1000 goes up to DN 1000 (ANSI 40"), with 0.5% or 0.2% accuracy and pressures up to 16 bar. Both models measure bidirectionally, have DIN or ANSI flanged connections and IP67/IP68 protection, so the sensor can also operate submerged in a chamber.
The APIS electropneumatic positioner moves a control valve to the exact position according to a 4-20 mA + HART signal, for linear strokes from 10 to 900 mm and rotary actuators up to 180°. Accuracy is 0.15% or 0.25%, the housing is stainless or galvanised steel, protection IP54/IP67, with an ATEX version for hazardous areas.
How to choose a flowmeter
The nominal size is chosen according to the flow rate, not just the existing pipe diameter: the optimum liquid velocity is 1 to 3 m/s, so for low flows a smaller flowmeter with reducers is often installed. The medium must be conductive (water, wastewater, acids, alkalis, milk, juices, pastes) and also determines the liner and electrode materials. The pressure and temperature of the medium (up to 90 °C) determine the flange rating, and the output signal (4-20 mA, pulse, frequency, Modbus RTU/RS485) the connection to the control system. Accurate measurement requires straight pipe runs upstream and downstream of the sensor and a completely full pipe.
Applications
Electromagnetic flowmeters are used in water supply and boreholes to measure water delivered, in wastewater treatment plants, in the chemical industry for acids, alkalis and dosing, in the food industry for milk, juices and pastes, and in the paint industry. APIS positioners work on control valves in district heating plants, refineries and process plants.
Complete measurement equipment in one place
Alongside flowmeters we offer pressure and level transmitters, digital indicators and pressure gauges from our own production, with technical support throughout.
For a quotation, send us the medium, minimum, normal and maximum flow, pipe diameter, pressure, temperature and required output signal. Our technical team will recommend a suitable solution within 24 hours. Contact us.
