MJ-WQS-EC Conductivity Sensor

MJ-WQS-EC is a simple yet reliable conductivity sensor for water quality monitoring

Designed to be easily integrated into a system, it comes with an RS485 Modbus protocol.

Built with IP68 housing, it is suitable for long term deployment underwater.

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MJ-WQS-EC is a digital output water electrical conductivity sensor developed and manufactured by MJ Instruments. With sensor body filled internally which acts as sensor weights as well as protecting the electronic components, the sensor is well suited for long-term deployment. The body is built with corrosive resistant material, allowing it to be deployed at industrial discharge for pollution monitoring. Different housing is also available upon request. With standard RS485 Modbus output, it is easy to integrate the sensor into the commercial controllers.

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Conductivity (Wiki)

Conductivity (or specific conductance) of an electrolyte solution is a measure of its ability to conduct electricity. The SI unit of conductivity is Siemens per meter (S/m). Conductivity measurements are used routinely in many industrial and environmental applications as a fast, inexpensive and reliable way of measuring the ionic content in a solution. For example, the measurement of product conductivity is a typical way to monitor and continuously trend the performance of water purification systems.

Electrolytic conductivity of ultra-high purity water as a function of temperature. In many cases, conductivity is linked directly to the total dissolved solids (T.D.S.). High-quality deionized water has a conductivity of about 0.5 μS/cm at 25 °C, typical drinking water is in the range of 200 – 800 μS/cm, while seawater is about 50 mS/cm (or 50,000 μS/cm). Conductivity is traditionally determined by connecting the electrolyte in a Wheatstone bridge. Dilute solutions follow Kohlrausch’s Laws of concentration dependence and additivity of ionic contributions. Lars Onsager gave a theoretical explanation of Kohlrausch’s law by extending Debye–Hückel theory.


EC Range

0 – 5 ms/cm

EC Accuracy

+-1% FS

EC Resolution


Temperature Range

0 – 50 Deg C

Temperature Accuracy

+- 0.2

Temperature Resolution


Temperature Compensation

0 to 80 Deg C

Max Pressure

50 Psig

Electrode Constant



RS485 Modbus

Protection Rating


Power Supply

DC 12V