The difference between continuous liquid level detection instruments and liquid level switch instruments!

1.Core functional differences

✅  Continuous liquid level detection instrument: precise measurement of "liquid level"

Real time and uninterrupted monitoring of the specific height and volume of the liquid level in the storage tank, and outputting standard signals with linear changes. Capable of tracking liquid level dynamics throughout the process, supporting data recording, remote display, and automatic adjustment, achieving precise liquid level control.

✅  Liquid level switch instrument: fixed-point judgment of whether the liquid level has reached or not

No specific numerical measurement function, only responsible for fixed-point state judgment. When the liquid level reaches the preset high or low point, the on/off switch signal is triggered, which is only used for alarm and interlock protection. It has a simple structure and strong protection.

2.Working principle and typical equipment

📌  Continuous detection instruments

By using physical principles such as pressure, sound waves, radar, and magnetic induction, the liquid level height is converted into a linear electrical signal, and the liquid level changes synchronously with the measured values.

Common equipment: radar level gauge, ultrasonic level gauge, magnetostrictive level gauge, input static pressure level gauge, etc.

📌  Liquid level switch instruments

By relying on the medium contact probe to trigger physical/capacitive changes, only the critical point state is recognized, and the switch signal is output when the liquid level reaches the point position, without continuous data output.

Common equipment: tuning fork level switch, vibrating rod level switch, float level switch, capacitive level switch, etc.

3.Differences in application scenarios

📍  Applicable scenarios for continuous detection instruments

Suitable for core working conditions that require measurement, monitoring, and automatic control, requiring real-time monitoring of material inventory:

Real time liquid level monitoring of chemical, sewage, and oil storage tanks

Production material measurement, data collection, remote operation and maintenance

Scenario of automatic adjustment of liquid level PID and precise process control

📍  Applicable scenarios for liquid level switch instruments

Suitable for high and low position protection, safety interlock scenarios, no need for precise numerical values, with a focus on safety protection:

Tank high-level overflow prevention and low-level pump idle prevention

Alarm for liquid level exceeding limit in reaction kettle, water tank, and storage tank

As a safety redundancy protection device for continuous liquid level instruments

4.Accuracy and Cost

Continuous detection instruments have high accuracy (usually 0.1% FS), which can meet quantitative measurement needs; The accuracy of the liquid level switch is mainly reflected in the accuracy of the threshold setting (usually ± 1% 5% FS), and there is no need to pay attention to the intermediate value. Continuous detection instruments have a more complex structure (requiring processing of continuous signals) and higher costs (ranging from hundreds to tens of thousands of yuan, such as radar level gauges); The liquid level switch has a simple structure and low cost (usually tens to thousands of yuan, such as float switches).
5.How to choose

If you need to know the specific liquid level (such as monitoring, metering, trend analysis), choose a liquid level continuous detection instrument; If you only need to "know if the liquid level has reached a certain point" (such as automatic control, over limit alarm), select the liquid level switch. In practical applications, the two are often used in combination: for example, in a liquid storage tank, a continuous detection instrument is used to monitor the real-time liquid level, and a liquid level switch is used to set high/low liquid level alarms, forming a dual guarantee.