A liquid level gauge is an instrument that measures the position of liquid in a container, and its working principle is usually based on various physical laws and effects, such as buoyancy, magnetism, sound waves, optics, etc. The following are several common level gauges and their working principles: 1. Magnetic flip plate level meter The working principle of magnetic flip plate level meter is based on the principle of buoyancy and magnetic coupling. When the liquid level in the measured container rises and falls, the permanent magnetic steel in the float is transferred to the tilting column indicator panel through magnetic coupling, causing the red and white tilting column to flip 180°. When the liquid level rises, the tilting column turns from white to red, and when the liquid level drops, the tilting column turns from red to white. The junction between red and white on the panel is the actual height of the liquid level in the container, so as to realize the liquid level display. 2. Float level meter The structure of float level meter is mainly designed and produced based on the principle of buoyancy and static magnetic field. The position of the float with a magnet (referred to as the float) in the measured medium is affected by the action of buoyancy: the change in the liquid level causes the change in the position of the magnetic float. The magnet in the float and the sensor (magnetic reed switch) act to change the number of components (such as fixed resistance) connected to the circuit, and then change the electrical quantity of the instrument circuit system. 3. Steel strip liquid level meter Steel strip liquid level meter is designed and produced using the principle of mechanical balance. When the liquid level changes, the original mechanical equilibrium will reach a new equilibrium through the movement of the steel strip under the disturbance of the float by the buoyancy. The liquid level detection device (float) drives the steel belt to move according to the liquid level, and the displacement transmission system drives the transmission pin to rotate through the movement of the steel belt, and then acts on the counter to display the liquid level. 4. Radar level meter Radar level meter is a measuring instrument based on the principle of time travel, radar waves run at the speed of light, and the running time can be converted into level signals through electronic components. The probe emits a high-frequency pulse that travels along the cable probe, and when the pulse hits the surface of the material, it is reflected back to be received by the receiver inside the meter, and the distance signal is converted into a level signal. 5. Magnetostrictive liquid level meter When the sensor of the magnetostrictive liquid level meter works, the circuit part of the sensor will excite a pulse current on the waveguide wire, and the current will propagate along the waveguide wire to generate a pulsed current magnetic field around the waveguide wire. Inside the float is a set of permanent magnetic rings. When the pulsed current magnetic field meets the magnetic ring magnetic field generated by the float, the magnetic field around the float changes so that the waveguide wire made of magnetostrictive material generates a torsional wave pulse at the location of the float, which is transmitted back along the waveguide wire at a fixed speed and detected by the detection mechanism. By measuring the time difference between the pulse current and the torsion wave, the position of the float, that is, the position of the liquid surface, can be precisely determined. 6. Rf admittance level meter RF admittance level meter is composed of sensor and control instrument. The sensor can be installed on the top of the warehouse by rod, coaxial or cable probe. The pulse card in the sensor can convert the level change into a pulse signal to the control instrument, and the control instrument is converted into the engineering quantity after calculation and processing, so as to realize the continuous level measurement. 7. Tuning fork level meter The working principle of the tuning fork level controller is to make the tuning fork vibrate at a certain resonant frequency through a pair of piezoelectric crystals installed on the tuning fork base. When the tuning fork is in contact with the measured medium, the frequency and amplitude of the tuning fork will change, and these changes are detected by the intelligent circuit, processed and converted into a switching signal. Conclusion The above are several common liquid level gauges and their working principles. Each level meter has its specific application scenario and use restrictions, and the characteristics of the measured medium, environmental conditions and installation requirements need to be considered when selecting the right level meter.
Working principle of liquid level gauge
2024 09/11