NBL-WQ-EC Online Water Conductivity EC Sensor

The NBL-WQ-EC online water conductivity sensor is designed for continuous measurement of electrical conductivity in drinking-water processes, surface water, water supply systems and industrial water treatment applications.

Four measurement ranges are available from 0–20.00 μS/cm up to 0–200.0 mS/cm, allowing the sensor to be selected for low-conductivity water, general water-quality monitoring or higher-conductivity process water. The sensor also provides temperature measurement and automatic temperature compensation using an integrated Pt1000 element.

With RS485 Modbus RTU, IP68 protection, 3/4 NPT mounting and configurable wetted materials, the NBL-WQ-EC can be connected to compatible PLCs, DCS systems, data loggers, RTUs and IoT gateways for continuous online water-quality monitoring.

NBL-WQ-EC Conductivity Sensor Technical Specifications

Choose the Correct Conductivity Measurement Range

Selecting the correct conductivity range is important because different water sources can differ by several orders of magnitude in electrical conductivity. A sensor range should cover the expected maximum conductivity without being unnecessarily oversized.

For very low-conductivity purified water, select the lower range so useful measurement resolution is retained. For general surface water, process water or wastewater, select the range according to actual or expected conductivity rather than choosing the widest range by default.

What Does an EC Conductivity Sensor Measure?

Electrical conductivity indicates how easily an electrical current can pass through water. Conductivity increases as the concentration and mobility of dissolved ions increase, so EC is widely used as an online indicator of changes in dissolved salts and ionic content.

Conductivity does not directly identify which salts, minerals or contaminants are present. Two water samples can have similar conductivity values while containing different dissolved ions. Laboratory analysis or parameter-specific sensors are required when the actual chemical composition must be identified.

Conductivity vs TDS

Conductivity and total dissolved solids are related, but they are not the same measurement. Conductivity is measured from the electrical behavior of dissolved ions, while TDS is commonly estimated from conductivity using a conversion coefficient.

The NBL-WQ-EC Modbus configuration includes a configurable TDS conversion coefficient. The default coefficient is 0.64 and can be changed according to the actual water composition when required.

Conductivity vs Salinity

Conductivity is strongly influenced by dissolved salts, but EC and salinity should not automatically be treated as identical values. A conductivity sensor provides electrical-conductivity data, while salinity conversion depends on the water composition and calculation method.

For seawater, desalination systems or projects where salinity is the primary required parameter, consider a dedicatedwater salinity sensorand confirm the required salinity range and units before ordering.

Why Is Temperature Compensation Important?

Water conductivity changes with temperature even when the ionic composition of the water remains unchanged. Without temperature compensation, a change in water temperature can appear as a change in conductivity.

The NBL-WQ-EC includes a Pt1000 temperature element and provides automatic temperature compensation so conductivity measurements can be interpreted more consistently across changing water temperatures.

RS485 Modbus Communication

The RS485 conductivity sensor uses Modbus RTU and can communicate directly with compatible PLCs, DCS systems, RTUs, data loggers, industrial computers and IoT gateways.

Measurement Register Structure

Starting from register address 0x0000, the Modbus measurement block contains six 16-bit registers representing the conductivity value, conductivity decimal position, temperature value, temperature decimal position, TDS value and TDS decimal position.

Use the protocol document supplied with the ordered sensor as the final integration reference because range configuration determines the conductivity scaling and decimal position.

Electrical Wiring

Check the wiring carefully before applying power. For long-term immersion or outdoor installations, all field wiring points and cable joints should be waterproofed and the extension cable should be selected for suitable corrosion resistance.

Immersion, Tank and Pipeline Installation

The NBL-WQ-EC supports immersion installation and uses a 3/4 NPT threaded connection, allowing integration into tanks, pipelines, water-treatment systems and online monitoring assemblies.

Conductivity Sensor Calibration

The NBL-WQ-EC supports two-point calibration, consisting of zero calibration and slope calibration.

Zero Calibration

Rinse the sensor with distilled water and remove residual liquid with clean filter paper. For the low-conductivity ranges, zero calibration is performed in air after the reading has stabilized. The exact zero-calibration procedure depends on the selected measurement range.

Slope Calibration

Place the sensor vertically in a known conductivity standard solution within the recommended calibration range. The current manual specifies a standard solution between approximately 10% of full scale and full scale for slope calibration.

During calibration, keep sufficient clearance between the sensing area and the container walls or bottom, especially for the higher-range configurations. After calibration, rinse the sensor according to the maintenance procedure before returning it to service.

Cleaning and Maintenance

The required maintenance interval depends on water composition, suspended solids, scaling, biological growth and the required measurement quality. Conductivity sensors used in wastewater or scaling water generally require more frequent inspection than sensors used in clean water.

Wetted Material Selection

Available wetted materials include ABS, SUS316L and PVC depending on configuration. Material selection should be based on the actual liquid composition rather than only the expected conductivity range.

For seawater, strong acids, alkalis, aggressive chemicals or industrial wastewater with uncertain composition, provide the chemical composition, concentration, temperature and operating pressure so material compatibility can be checked before ordering.

Online Water Quality Monitoring System Integration

Conductivity Sensor → RS485 Modbus → PLC / Data Logger / RTU → 4G / Ethernet → SCADA / Cloud Platform / Private Server

The NBL-WQ-EC provides conductivity, temperature and supported TDS data through its RS485 interface. Remote 4G, Ethernet, Wi-Fi, MQTT or HTTP communication requires a compatible data logger or IoT gateway and is not built into the basic conductivity sensor.

For multi-parameter projects, the sensor can be combined with otheronline water quality sensorssuch as pH, dissolved oxygen, turbidity, ORP and ammonia nitrogen sensors.

Water Conductivity Sensor Applications

The NBL-WQ-EC is suitable for continuous monitoring where changes in dissolved ionic content need to be tracked. The correct range and wetted material should be selected according to the actual water source and process conditions.

Surface Water Monitoring  •  Water Treatment  •  Industrial Process Water  •  Water Supply Systems
Groundwater Monitoring  •  Aquaculture  •  Irrigation Water  •  Industrial Wastewater

How to Select an Online Conductivity Sensor

NBL-WQ-EC Conductivity Sensor FAQ

Q1. What does the NBL-WQ-EC measure?

A1. It measures water electrical conductivity and temperature. Supported configurations also provide a TDS value calculated from conductivity.

Q2. What conductivity ranges are available?

A2. Available ranges are 0–20.00 μS/cm, 0–200.0 μS/cm, 0–5000 μS/cm and 0–200.0 mS/cm.

Q3. Does the sensor support automatic temperature compensation?

A3. Yes. The NBL-WQ-EC uses an integrated Pt1000 element for automatic temperature compensation.

Q4. Does it support RS485 Modbus?

A4. Yes. The standard digital output is RS485 using Modbus RTU.

Q5. Is TDS directly measured?

A5. TDS is derived from the conductivity measurement using a conversion coefficient rather than independently measuring every dissolved solid. The default TDS coefficient is 0.64 and can be adjusted according to the water conditions.

Q6. Is conductivity the same as salinity?

A6. No. Conductivity measures the water's ability to conduct electrical current. Salinity can be estimated from conductivity under defined conditions, but the conversion depends on water composition and the required calculation method.

Q7. Can the sensor remain submerged?

A7. Yes. The sensor is rated IP68 and supports immersion installation. External cable joints must also be correctly waterproofed for long-term wet installations.

Q8. Does the sensor require calibration?

A8. Yes. The sensor supports zero and slope calibration. The calibration interval depends on water conditions, fouling and required data quality.

Q9. Can the conductivity sensor connect to a customer's PLC or data logger?

A9. Yes. It can connect to compatible PLCs, DCS systems, RTUs, data loggers and gateways that support RS485 Modbus RTU.

Q10. Can the sensor send data directly through 4G?

A10. The basic sensor does not contain a 4G modem. Connect it to a compatible data logger or IoT gateway when cellular, Ethernet, MQTT, HTTP or private-server communication is required.

NBL-WQ-EC Conductivity Sensor User Manual

NBL-WQ-EC-Online-Conductivity-Sensor-User-Manual.pdf

Request an NBL-WQ-EC Conductivity Sensor Quotation

For model selection and quotation, provide the expected conductivity range, water type, chemical composition where relevant, operating temperature, pressure, installation method, cable length, quantity and receiving PLC, RTU or data logger.

For complete water-quality monitoring projects, also specify whether pH, dissolved oxygen, turbidity, ORP, ammonia nitrogen, water level, a data logger, 4G gateway, cloud platform or private-server integration is required.