A magnetostrictive level indicator is a type of level measurement device used to measure liquid levels in storage tanks. It operates based on the principle of magnetostriction, which is the property of certain materials to change their shape when subjected to a magnetic field.
Here's how a magnetostrictive level indicator typically works:
Construction: The magnetostrictive level indicator consists of a rigid, tubular probe made of a magnetostrictive material, usually an alloy of iron and nickel. This probe is inserted vertically into the tank so that it can reach the liquid level to be measured.
Electronics: The probe contains built-in electronics, including a waveguide and a pulse generator. The waveguide is a wire coil that surrounds the magnetostrictive probe.
Initial condition: When the level indicator is not measuring the liquid level, an initial electrical pulse is sent through the waveguide coil.
Measurement process: When the probe comes in contact with the liquid, the level indicator system detects the interface between the liquid and the gas or vapor above it.
Magnetostriction effect: Once the probe is in contact with the liquid, a second pulse, known as the interrogation pulse, is sent through the waveguide coil. This pulse generates a magnetic field around the probe.
Magnetic field interaction: The magnetic field interacts with the magnetostrictive material in the probe, causing it to experience a torsional stress wave. This stress wave travels along the probe at a known velocity.
Detection: The level indicator system detects the time it takes for the torsional stress wave to travel from the top of the probe to the liquid level and back to the waveguide. This time measurement is very precise and is used to calculate the distance from the top of the probe to the liquid level.
Calibration: Before using the magnetostrictive level indicator, it must be calibrated to establish the relationship between the time delay and the actual liquid level. This calibration accounts for factors such as the tank's dimensions and the properties of the liquid being measured.
Output: The calculated liquid level is then displayed on a local indicator or transmitted to a remote monitoring system or controller.
Overall, magnetostrictive level indicators are known for their accuracy, reliability, and ability to measure liquid levels in a wide range of industrial applications. They are commonly used in storage tanks, fuel tanks, chemical processing vessels, and other liquid-containing systems.