In measurement, ultrasonic pulses are emitted by sensors (transducers), and the sound waves are reflected by the liquid surface and received by the same sensor or ultrasonic receiver. They are converted into electrical signals through piezoelectric crystals or magnetostrictive devices, and the distance from the sensor to the measured liquid surface is calculated based on the time between the emission and reception of the sound waves. Due to the use of non-contact measurement, the measured medium is almost unrestricted and can be widely used for measuring the height of various liquid and solid materials.
The ultrasonic level gauge consists of three parts: ultrasonic transducer, processing unit, and output unit.
Ultrasonic level gauges can adopt two-wire, three wire, or four wire technology. The two-wire system is: power supply and signal output are shared; The three wire system is: the power supply circuit and the signal output circuit are independent. When using DC 24V power supply, a 3-core cable can be used, and the negative end of the power supply and the negative end of the signal output share the same core wire; The four wire system is: when using AC 220V power supply, or when using DC 24V power supply and requiring isolation between the power supply circuit and the signal output circuit, a 4-core cable should be used. DC or AC power supply, with 4-20mADC and high/low switch output.
Range: 0-50 meters, multiple forms to choose from, suitable for various corrosive and chemical applications, high precision, remote signal output, PLC system monitoring.
working principle
The working principle of an ultrasonic level gauge is that high-frequency pulse sound waves emitted by an ultrasonic transducer (probe) are reflected back on the surface of the measured level (material) and converted into electrical signals by the transducer The propagation time of sound waves is directly proportional to the distance they travel to the surface of an object The relationship between sound wave transmission distance S, sound velocity C, and sound transmission time T can be expressed by the formula: S=C × T/2
Due to the certain width of the emitted ultrasonic pulses, the reflected waves in a small area close to the transducer overlap with the emitted waves, making it difficult to identify and measure their distance values. This area is called the measurement blind spot. The size of the blind spot is related to the model of the ultrasonic level gauge.
The probe emits ultrasonic waves, which are then reflected by the liquid surface and received by the probe. The distance between the probe and the liquid (object) surface is proportional to the time the ultrasonic waves have passed
Distance [m]=Time x Sound Speed/2 [m]
Temperature compensation formula for sound velocity: environmental sound velocity=331.5+0.6 × temperature
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