A basic magnetic flowmeter, also known as an electromagnetic flowmeter, is a device used to measure the flow rate of electrically conductive fluids (such as water, sewage, or various industrial liquids) in pipes. It operates on the principle of Faraday's law of electromagnetic induction. The basic components of a magnetic flowmeter include:
Flow Tube: This is the primary component of the flowmeter and is inserted into the pipeline through which the fluid flows. The flow tube is typically made of a non-conductive material, such as plastic or glass, to avoid electrical interference. It contains an inner lining that comes into direct contact with the fluid, which should be electrically conductive.
Coils: The flowmeter has two coils wound around the flow tubeβone coil serves as the electromagnetic transmitter, and the other as the receiver. These coils are typically wrapped around the outside of the flow tube, perpendicular to the direction of fluid flow.
Magnetic Field: When the fluid flows through the flow tube, a magnetic field is generated by applying a current to the electromagnetic transmitter coil. The strength of this magnetic field is directly proportional to the strength of the electrical current passing through the coil.
Electromotive Force (EMF) Measurement: As the conductive fluid flows through the magnetic field, it induces an electromotive force (EMF) proportional to the fluid's velocity and the magnetic field strength. This EMF is detected by the electromagnetic receiver coil.
Signal Conversion and Measurement: The induced EMF is then converted into an electrical signal, which is proportional to the flow velocity of the fluid. This signal is processed by the flowmeter's electronics to calculate the volumetric flow rate.
Output Display: The flow rate information can be displayed on the flowmeter's screen, and in some cases, it can be transmitted to other control or monitoring systems for further processing or recording.
One of the advantages of magnetic flowmeters is that they can measure flow rates accurately and consistently, even in challenging conditions like abrasive fluids or turbulent flows. However, it's important to note that magnetic flowmeters can only measure electrically conductive fluids and are not suitable for non-conductive fluids, such as most gases or hydrocarbons.