What is an ultrasonic level gauge

What is an ultrasonic level gauge?

Ultrasonic level gauge is an instrument that uses the principle of ultrasonic reflection to achieve non-contact level measurement. By emitting ultrasonic waves and receiving their reflected echoes from the liquid surface, the height of the liquid level is calculated by calculating the propagation time of the sound waves. It is widely used for liquid level monitoring of various liquids such as water, oil, chemical solvents, etc. It has the characteristics of easy installation, non-contact with the measured medium, and adaptability to various working conditions.

1、 Core working principle

Transmission and reception:The probe (transducer) of the liquid level gauge emits high-frequency ultrasonic signals (usually 20kHz-200kHz）After the signal reaches the liquid level, it is reflected back and then received by the probe.

Time calculation:The built-in processor of the instrument records the time from transmission to reception of ultrasonic waves (round-trip time), combined with the propagation speed of ultrasonic waves in the air (approximately) 340m/sDue to temperature influence, some models will automatically compensate for temperature. Calculate the vertical distance between the probe and the liquid surface using the formula: distance=2Propagation speed x round-trip time

Liquid level conversion:Given the installation height of the probe (distance from the bottom of the container), subtract the calculated value from the installation height The actual liquid level height can be obtained by measuring the distance from the probe to the liquid level.

2、 Basic composition structure

Probe (transducer): the core component responsible for transmitting and receiving ultrasonic waves, mostly made of materials such as ABSPlastic, stainless steel, or polytetrafluoroethylene (depending on the working conditions, such as polytetrafluoroethylene for corrosion-resistant scenarios).

Host (controller): includes circuit modules, processors, and display screens, used for processing signals, calculating liquid levels, and displaying measured values (some models have buttons for parameter settings).

Cable: Connect the probe to the host and transmit electrical signals (some integrated models do not have separate cables).

3、 Main features

Non contact measurement: The probe does not come into direct contact with the measured liquid, avoiding problems such as medium corrosion, adhesion of viscous substances, and blockage. It is especially suitable for dirty, corrosive, or highly hygienic liquids (such as sewage and food raw materials).

Easy installation: It is usually fixed on the top of the container through a bracket, without the need for openings or intrusion into the interior of the container, and requires minimal modifications to the original system.

局限性：

Large environmental impact: strong air flow, steam, foam and dust will interfere with sound wave propagation, resulting in inaccurate measurement or signal loss;

Blind spot: within a certain distance below the probe (usually 0.1-1Meter (varies depending on the measurement range) cannot be measured, sufficient space needs to be reserved;

Not suitable for vacuum or high-pressure sealed containers: Ultrasonic waves cannot propagate in vacuum, and high pressure may affect the characteristics of sound waves.

4、 Typical application scenarios

As mentioned earlier, ultrasonic level gauges are widely used in water treatment (sedimentation tanks, sewage tanks), industrial storage tanks (chemical raw materials, lubricants), municipal facilities (fire water tanks, sewers), agricultural irrigation (reservoirs) and other scenarios, and are one of the commonly used equipment for level monitoring.