Working Principle of Ultrasonic Flow Meter

Sound waves are divided into two categories according to their properties: electromagnetic waves and mechanical waves. Electromagnetic waves are generated by the action of electromagnetic forces and are the process of electromagnetic field changes propagating in space. Electromagnetic waves can be divided into radio waves, infrared rays, visible light, ultraviolet light, X-rays, etc. according to their frequency. Mechanical waves are the propagation of mechanical fluctuations generated by mechanical forces in a medium. They propagate mechanical energy and can only propagate in a medium. Sound waves are a type of mechanical wave, which are divided into infrasound waves, audible sound waves, and ultrasonic waves according to their frequency. Waves with frequencies below 20Hz are infrasound waves; waves with frequencies between 20 and 20,000Hz are audible sound waves; waves with frequencies above 20kHz are called ultrasonic waves.

Ultrasonic waves are mechanical vibration waves with a frequency above 20kHz. They have good directivity, concentrated energy, and strong penetrating ability. They can penetrate steel plates several meters thick and have low energy consumption. When encountering the interface between two media, they can produce obvious reflection and refraction phenomena.

Ultrasonic waves decay to a certain extent during propagation, which is caused by the medium absorbing the energy of ultrasonic waves. Ultrasonic waves decay quickly in the air, especially when the frequency is high, so when propagating in the air, low-frequency ultrasonic waves are used, generally tens of kHz (40kHz). In liquids and solids, the attenuation is slow and the propagation is far, so higher frequencies can be used, generally hundreds of kHz or higher.

Ultrasonic sensors have a wide range of applications and can be used to measure flow (ultrasonic flow meter), liquid level (ultrasonic level meter), object level (ultrasonic level meter), material thickness and anti-theft alarm.