Liquid Level Sensor for Water Level, Oil & Mild-corrosive Liquid Level Monitoring

Liquid Level Sensor for Stable Monitoring Solution 

Liquid Level Sensor for Water Level, Oil Level, and Mildly Corrosive Liquids

In industrial automation, hydraulic engineering, agricultural irrigation, and IoT monitoring systems, liquid level is one of the most basic yet critical process parameters. The stability and long-term reliability of liquid level measurement directly impact system safety, operational efficiency, and later maintenance costs.

The NiuBoL PM200 series Liquid Level Sensor is a submersible liquid level sensor designed for long-term online applications. It is specifically engineered for monitoring the level of water, oil, and mildly corrosive liquids that have no significant corrosion effect on stainless steel, balancing measurement accuracy, engineering adaptability, and system integration capabilities.

Liquid Level Sensor Product Overview

The NiuBoL Liquid Level Sensor adopts the mature diffused silicon piezoresistive measurement principle, converting liquid static pressure changes into high-precision electrical signals. These signals undergo temperature compensation, linear correction, and digital processing through a built-in micro signal processing circuit, and are output via RS485 communication for long-distance, stable data transmission.

The sensor front end is equipped with a protective cap structure, which effectively protects the sensitive diaphragm while ensuring smooth contact of the liquid with the measurement area. The waterproof cable is integrally sealed with the housing, and the internal vent tube connects to the external atmosphere through the cable. Combined with an anti-condensation structural design, the sensor can operate stably when long-term immersed in liquid.

This series features small size, light weight, and a wide range coverage, suitable for space-constrained or complex working condition applications. It has been widely used in water plants, wastewater treatment plants, urban water supply systems, pools, wells, geothermal wells, mines, industrial storage tanks, reservoirs, rivers, and marine liquid level monitoring fields.

Liquid Level Sensor Measurement Principle and Technical Advantages

Diffused Silicon Piezoresistive Measurement Principle

When the liquid level height changes, the static pressure acting on the sensor diaphragm changes accordingly. The internal diffused silicon piezoresistive chip senses the pressure change and generates a corresponding electrical signal. After high-stability amplification, filtering, and digital processing, this signal outputs precise liquid level data.

This measurement principle is mature, with good repeatability, and is particularly suitable for continuous online measurement and long-term operation scenarios.

Intelligent Signal Processing and Data Stability

The PM200 series is equipped with low-power ADI professional chips and microprocessors. Through automatic correction algorithms and digital filtering technology, it effectively suppresses numerical jumps caused by liquid surface fluctuations and minor disturbances, making the output data smoother and more reliable for use in control systems.

Liquid Level Sensor Functional Features

• Reverse polarity protection and instantaneous overcurrent/overvoltage protection, meeting industrial EMI protection requirements

• High-quality vented cable design, suitable for long-term immersion in liquids

• Strong overload capability and excellent anti-interference performance, suitable for complex field environments

• Intelligent correction algorithm, effectively reducing data instability caused by water surface fluctuations

• Sloped liquid guide hole structure, reducing entry of sludge and impurities while improving impact resistance

• Submersible measurement method, simple installation, no complex mechanical structure required

• Multi-layer protection structure design, overall protection rating up to IP68

• Corrosion-resistant stainless steel material, adaptable to various industrial and environmental applications

• RS485 digital signal output, communication distance up to 2000 meters

• DC 10–30V wide voltage power supply, strong system compatibility

Liquid Level Sensor Main Technical Parameters

System Integration and Application Recommendations

Integration with PLC / RTU / DTU

Thanks to the standard RS485 communication interface, the NiuBoL Liquid Level Sensor can be directly connected to mainstream PLCs, RTUs, data acquisition modules, or industrial gateways without additional signal conversion equipment, reducing system complexity and failure risks.

Typical application methods for Liquid Level Sensor include:

• Liquid level monitoring and pump station linkage in PLC control systems

• Uploading to SCADA or cloud platforms via RTU or DTU

• Forming comprehensive monitoring systems with water quality, meteorological, and other sensors

Application Advantages in IoT Projects

In IoT applications, liquid level monitoring typically requires long-term stable operation, low maintenance costs, and remote data transmission capabilities. This series adopts low-power design and supports wide voltage power supply, making it suitable for use with solar and battery power systems.

Combined with 4G, NB-IoT, LoRa, and other wireless communication modules, it can build complete remote liquid level monitoring solutions, widely applied in:

• Agricultural irrigation and water resource management

• Urban drainage and flood warning

• Unattended reservoir and river channel monitoring

• Distributed pump station liquid level collection

Selection and Usage Recommendations

Range Selection Recommendations

It is recommended that the liquid level sensor range be slightly higher than the actual maximum liquid level height, generally selected as maximum liquid level × 1.2～1.3, to avoid long-term operation near full scale affecting accuracy and lifespan.

Liquid Level Sensor Medium Adaptability Description

This product is suitable for water, oil, and liquids with no obvious corrosion to stainless steel. For high-salinity, strong acid, or strong alkali media, it is recommended to confirm material compatibility with the NiuBoL technical team before selection.

Comparison Advantages with Other Liquid Level Measurement Solutions

Compared with float level gauges, ultrasonic level gauges, and other solutions, the submersible liquid level sensor has the following advantages:

• Unaffected by foam, steam, and gas interference

• Simple installation structure, suitable for narrow or enclosed spaces

• Good long-term stability, suitable for continuous online monitoring

• High protection performance, can be directly immersed for use

In complex working conditions or projects with high reliability requirements, the submersible liquid level measurement solution offers higher overall cost-effectiveness.

Liquid Level Sensor Installation and Wiring Instructions

Pre-Installation Check

The device includes upon delivery:

• General submersible liquid level sensor 1 unit

• Certificate of Conformity, Warranty Card

Wiring Method (RS485)

• Power positive: Red wire or brown wire (24VDC +)

• Power negative: Blue wire or black wire (24VDC -)

• RS485 A: Yellow wire

• RS485 B: White wire or blue wire

Installation Precautions

• Avoid burying or blocking the probe with sediment during installation

• Wiring must follow instructions; incorrect wiring may damage the circuit

• Strictly prohibit collision, dropping, or touching the sensor diaphragm

• When liquid surface fluctuation is large, it is recommended to add counterweight to fix the probe

• The vented cable should avoid squeezing or sharp bending; keep the vent outlet facing downward to prevent water entry

FAQ:

1. Device cannot communicate with PLC or computer?
   Please check COM port selection, whether device addresses are duplicated, whether communication parameters are consistent, and whether RS485 A/B is reversed.

2. Large fluctuations in liquid level data, what is the reason?
   Common causes include large liquid surface disturbance, unfixed probe, or abnormal vent tube. It is recommended to fix the probe and check the vented cable condition.

3. Can multiple liquid level sensors share one RS485 bus?
   Yes, but unique addresses must be set, and bus length and number of nodes should be reasonably controlled. Add terminating resistors or repeaters if necessary.

4. Does the sensor require regular calibration?
   Under normal conditions, frequent calibration is not required. For high-precision projects, calibration can be performed annually or according to project specifications.

5. What is the impact if the vented cable gets water inside?
   The vented cable is used for atmospheric pressure compensation; water ingress or blockage will directly affect measurement accuracy and should be protected重点.

6. Is it suitable for long-term unattended operation?
   Yes. The product is designed for long-term online monitoring, with high protection rating and good stability, suitable for unattended application scenarios.

Summary

The NiuBoL Liquid Level Sensor is a mature submersible liquid level monitoring solution oriented toward engineering systems and IoT applications. Its diffused silicon piezoresistive measurement technology, RS485 digital communication capability, IP68 protection structure, and good system compatibility enable it to continuously provide stable and reliable liquid level data in complex, long-term operating environments.

For liquid level monitoring projects that pursue stable operation, easy integration, and controllable maintenance costs, the NiuBoL Liquid Level Sensor is a professional solution worthy of long-term selection.