A magnetostrictive liquid level sensor is a type of level measurement device used to determine the level of liquid in containers or tanks, particularly those containing granular materials. It operates based on the magnetostrictive principle, which involves the interaction of magnetic fields with magnetostrictive materials. Here's an explanation of how this sensor works in granular materials:
Magnetostrictive Principle: Magnetostriction is the phenomenon in which certain materials change their shape or dimensions when exposed to a magnetic field. These materials typically consist of ferromagnetic elements, like iron, combined with other alloying elements.
Sensor Construction: The magnetostrictive liquid level sensor is designed as a rod-like probe, usually made of a magnetostrictive material, which is inserted into the container or tank that holds the granular material. The sensor is typically rigid to withstand the pressure and forces exerted by the granular material.
Magnetic Float: To measure the level of liquid in granular materials, a magnetic float is attached to the liquid's surface. This float contains a magnet, and as the liquid level rises or falls, the float moves along the probe, changing its position relative to the magnetostrictive material.
Sending a Pulse: To initiate the level measurement, an electronic pulse is generated, usually from the sensor's electronics unit. This pulse travels down the probe, and it encounters the magnetic float.
Interaction with the Magnetic Float: When the pulse reaches the magnetic float, it generates a magnetic field around the float. The magnetostrictive material in the probe is affected by this magnetic field, causing it to experience a mechanical deformation known as the magnetostrictive effect. This deformation creates a stress wave that propagates back towards the sensor's electronics unit.
Time-of-Flight Measurement: The sensor's electronics unit measures the time it takes for the stress wave to travel from the probe's base to the float and back. Since the speed of sound in the probe is known and constant, the time-of-flight measurement can accurately determine the position of the float along the probe.
Calculating the Liquid Level: With the position of the magnetic float known, the sensor's electronics can calculate the liquid level by comparing the float's position with the reference point on the probe. The reference point is typically the top of the probe when the tank is empty.
Output and Display: The calculated liquid level is then converted into an appropriate output signal, such as a current, voltage, or digital signal, which can be used to display the level on a local indicator, transmit the data to a control system, or perform other automated actions.
By utilizing the magnetostrictive principle, the magnetostrictive liquid level sensor offers precise and reliable level measurements in tanks containing granular materials, making it suitable for various industrial applications where accurate liquid level monitoring is crucial.