The working principle of a magnetic level transmitter is based on the buoyancy principle and the magnetic field interaction between a float and a stationary magnet. It is used for measuring the level of liquids in tanks or vessels. Here’s an overview of how magnetic level transmitters work:
- Construction:
A magnetic level transmitter consists of two main components: a float and a stationary magnet. The float is typically buoyant and moves up and down with the liquid level. The float contains a magnetic element, such as a magnet or a magnetic material. - Magnetic Field Interaction:
The stationary magnet is positioned outside the tank or vessel and aligned with the float’s path. As the float moves up and down with the liquid level, the magnetic field of the stationary magnet interacts with the magnetic element inside the float. - Magnetic Field Strength Variation:
The strength of the magnetic field interaction between the stationary magnet and the magnetic element inside the float changes as the float moves. When the float is at its lowest point, closest to the magnet, the magnetic field strength is at its maximum. As the float rises, the magnetic field strength decreases. - Sensor and Transmitter:
The magnetic level transmitter includes a sensor or a set of sensors positioned near the path of the float. These sensors detect the change in magnetic field strength caused by the movement of the float. The sensors generate an electrical signal proportional to the liquid level. - Calibration and Output:
The electrical signal from the sensors is calibrated and converted into a corresponding level measurement. This measurement can be displayed locally on the transmitter or transmitted as an output signal, such as 4-20 mA analog or digital signals, for further processing or control. - Level Measurement Range:
The range of level measurement offered by a magnetic level transmitter depends on the design of the float, the length of the probe or guide tube on which the float moves, and the positioning of the stationary magnet.
Advantages:
- Simple and reliable operation.
- No direct contact between the sensor and the liquid, reducing the risk of corrosion or contamination.
- Suitable for a wide range of liquid applications, including corrosive or hazardous substances.
- Can handle high-temperature and high-pressure environments.
Limitations:
- Limited effectiveness in applications with opaque or non-magnetic liquids.
- The presence of debris or build-up on the float can affect measurement accuracy.
- The design may require careful consideration to avoid interference from other magnetic sources.
Magnetic level transmitters provide a reliable and cost-effective solution for level measurement in various liquid applications. They are widely used in industries such as chemical processing, water treatment, oil and gas, and others where accurate and continuous level monitoring is required.