Laboratory Conductivity Sensors: For a Wide Range of Applications

Laboratory Conductivity Sensor

Accurate Conductivity Electrodes and Probes For a Wide Range of Applications

Reliable Results

Proven laboratory and field conductivity sensor technologies ensure accurate and precise results in low and high conductivity ranges.

Easy to Use

A conductivity cell with a certified constant only requires verification before use. You save the time formerly spent on calibration.

Built to Last

Durable shaft and electrode materials create robust conductivity sensors that cope with diverse environments to ensure a long, useful lifetime—even when measuring challenging samples.

 

Reliable Meters

pH Meters

We offer a variety of durable benchtop and portable meters that work seamlessly with your laboratory conductivity probe or field sensor. Our portfolio has options to meet your needs for compliance and routine measurements, and it includes economical models for those working under tight budgets.

Benchtop MetersPortable Meters

Quality Solutions

pH Solutions

The results you obtain with your conductivity probe are only as accurate as the standards you use during calibration or verification. We offer a comprehensive range of quality standards in small bottles or specialized single-use sachets that eliminate contamination risk entirely.

More Information on Conductivity Standards

Expert Application Support

Service for pH meters and sensors

Our pH Competence and Support Center (pH CSC) offers you easy access to dedicated application specialists for your pH, ORP, ion, conductivity, and DO measurements. These specialists provide know-how and collaborate with product management and development to help ensure a high degree of success in all your critical electrochemical analyses.

Learn More about the ph CSC
 
Analytical Instruments

Products and Specs

 
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Measuring range
Temperature range
Connector
Cell type
Cell Constant
Material No.: 51302885
Measuring range0.001 – 500 mS/cm ;
Temperature range0 °C ; 100 °C ;
ConnectorMini-DIN ;
Cell type4 platinum poles ;
Cell Constant-- ;
Shaft MaterialEpoxy ;
Shaft Diameter7 mm ;
Cable1.2 m ;
ParameterConductivity ;
Intelligent Sensor Management (ISM®)No ;
Temperature probeNTC 30 kΩ ;
For portable meterNo ;
Signal typeAnalog ;
SampleDensity/Refractometry ;
Shaft length
Low Maintenance
Material No.: 51302256
Measuring range0.01 – 500 mS/cm ;
Temperature range0 °C ; 100 °C ;
ConnectorMini-DIN ;
Cell type4 platinum poles ;
Cell Constant0.80 cm-1 ;
Shaft MaterialGlass ;
Shaft Diameter12 mm ;
Cable1.2 m ;
ParameterConductivity ;
Intelligent Sensor Management (ISM®)No ;
Temperature probeNTC 30 kΩ ;
For portable meterNo ;
Signal typeAnalog ;
SampleHigh-ion strength ;
Shaft length120 mm ;
Low MaintenanceYes ;
Material No.: 51302401
Measuring range0.01 – 500 mS/cm ;
Temperature range0 °C ; 100 °C ;
ConnectorMini-DIN ;
Cell type4 platinum poles ;
Cell Constant-- ;
Shaft MaterialEpoxy ;
Shaft Diameter12 mm ;
Cable1.2 m ;
ParameterConductivity ;
Intelligent Sensor Management (ISM®)No ;
Temperature probeNTC 30 kΩ ;
For portable meterNo ;
Signal typeAnalog ;
SampleTitration ;
Shaft length120 mm ;
Low Maintenance
Material No.: 51302255
Measuring range0.1 – 500 µS/cm ;
Temperature range0 °C ; 100 °C ;
ConnectorMini-DIN ;
Cell type2 platinum poles ;
Cell Constant0.06 cm-1 ;
Shaft MaterialGlass ;
Shaft Diameter12 mm ;
Cable1.2 m ;
ParameterConductivity ;
Intelligent Sensor Management (ISM®)No ;
Temperature probeNTC 30 kΩ ;
For portable meterNo ;
Signal typeAnalog ;
Samplenon-aquous samples ;
Shaft length120 mm ;
Low MaintenanceYes ;
Material No.: 51344020
Measuring range0.01 – 1000 mS/cm ;
Temperature range0 °C ; 100 °C ;
ConnectorMini-DIN ;
Cell type4 graphite poles ;
Cell Constant0.57 cm-1 ;
Shaft MaterialEpoxy ;
Shaft Diameter12 mm ;
Cable1.2 m ;
ParameterConductivity ;
Intelligent Sensor Management (ISM®)No ;
Temperature probeNTC 30 kΩ ;
For portable meterNo ;
Signal typeAnalog ;
SampleGeneral Purpose ;
Shaft length120 mm ;
Low MaintenanceYes ;
Material No.: 51344022
Measuring range0.01 – 1000 mS/cm ;
Temperature range0 °C ; 100 °C ;
ConnectorMini-DIN ;
Cell type4 graphite poles ;
Cell Constant0.57 cm-1 ;
Shaft MaterialEpoxy ;
Shaft Diameter12 mm ;
Cable2 m ;
ParameterConductivity ;
Intelligent Sensor Management (ISM®)No ;
Temperature probeNTC 30 kΩ ;
For portable meterNo ;
Signal typeAnalog ;
SampleGeneral Purpose ;
Shaft length120 mm ;
Low MaintenanceYes ;
Material No.: 30014092
Measuring range0.01 – 1000 mS/cm ;
Temperature range0 °C ; 100 °C ;
ConnectorMini-DIN ;
Cell type4 graphite poles ;
Cell Constant0.57 cm-1 ;
Shaft MaterialEpoxy ;
Shaft Diameter12 mm ;
Cable1.2 m ;
ParameterConductivity ;
Intelligent Sensor Management (ISM®)Yes ;
Temperature probeNTC 30 kΩ ;
For portable meterNo ;
Signal typeAnalog ;
SampleGeneral Purpose ;
Shaft length120 mm ;
Low MaintenanceYes ;
Material No.: 30014093
Measuring range0.01 – 1000 mS/cm ;
Temperature range0 °C ; 100 °C ;
ConnectorMini-DIN ;
Cell type4 graphite poles ;
Cell Constant0.57 cm-1 ;
Shaft MaterialEpoxy ;
Shaft Diameter12 mm ;
Cable2 m ;
ParameterConductivity ;
Intelligent Sensor Management (ISM®)Yes ;
Temperature probeNTC 30 kΩ ;
For portable meterNo ;
Signal typeAnalog ;
SampleGeneral Purpose ;
Shaft length120 mm ;
Low MaintenanceYes ;
Material No.: 51344120
Measuring range0.01 – 1000 mS/cm ;
Temperature range0 °C ; 100 °C ;
ConnectorLTW (IP67) ;
Cell type4 graphite poles ;
Cell Constant0.57 cm-1 ;
Shaft MaterialEpoxy ;
Shaft Diameter12 mm ;
Cable1.8 m ;
ParameterConductivity ;
Intelligent Sensor Management (ISM®)No ;
Temperature probeNTC 30 kΩ ;
For portable meterYes ;
Signal typeAnalog ;
SampleGeneral Purpose ;
Shaft length120 mm ;
Low MaintenanceYes ;
Material No.: 51344124
Measuring range0.01 – 1000 mS/cm ;
Temperature range0 °C ; 100 °C ;
ConnectorLTW (IP67) ;
Cell type4 graphite poles ;
Cell Constant0.57 cm-1 ;
Shaft MaterialEpoxy ;
Shaft Diameter12 mm ;
Cable10 m ;
ParameterConductivity ;
Intelligent Sensor Management (ISM®)No ;
Temperature probeNTC 30 kΩ ;
For portable meterYes ;
Signal typeAnalog ;
SampleGeneral Purpose ;
Shaft length120 mm ;
Low MaintenanceYes ;
Material No.: 51344110
Measuring range0.01 – 1000 mS/cm ;
Temperature range0 °C ; 100 °C ;
ConnectorLTW (IP67) ;
Cell type4 graphite poles ;
Cell Constant0.57 cm-1 ;
Shaft MaterialEpoxy ;
Shaft Diameter12 mm ;
Cable1.8 m ;
ParameterConductivity ;
Intelligent Sensor Management (ISM®)Yes ;
Temperature probeNTC 30 kΩ ;
For portable meterYes ;
Signal typeAnalog ;
SampleGeneral Purpose ;
Shaft length120 mm ;
Low MaintenanceYes ;
Material No.: 51344114
Measuring range0.01 – 1000 mS/cm ;
Temperature range0 °C ; 100 °C ;
ConnectorLTW (IP67) ;
Cell type4 graphite poles ;
Cell Constant0.57 cm-1 ;
Shaft MaterialEpoxy ;
Shaft Diameter12 mm ;
Cable10 m ;
ParameterConductivity ;
Intelligent Sensor Management (ISM®)Yes ;
Temperature probeNTC 30 kΩ ;
For portable meterYes ;
Signal typeAnalog ;
SampleGeneral Purpose ;
Shaft length120 mm ;
Low MaintenanceYes ;
Material No.: 51344024
Measuring range0.001 – 500 µS/cm ;
Temperature range0 °C ; 100 °C ;
ConnectorMini-DIN ;
Cell type2 steel poles ;
Cell Constant0.105 cm-1 ;
Shaft MaterialStainless Steel ;
Shaft Diameter12 mm ;
Cable1.2 m ;
ParameterConductivity ;
Intelligent Sensor Management (ISM®)No ;
Temperature probeNTC 30 kΩ ;
For portable meterNo ;
Signal typeAnalog ;
SampleLow-ion strength (pure water) ;
Shaft length120 mm ;
Low MaintenanceYes ;
Material No.: 51344026
Measuring range0.001 – 500 µS/cm ;
Temperature range0 °C ; 100 °C ;
ConnectorMini-DIN ;
Cell type2 steel poles ;
Cell Constant0.105 cm-1 ;
Shaft MaterialStainless Steel ;
Shaft Diameter12 mm ;
Cable5 m ;
ParameterConductivity ;
Intelligent Sensor Management (ISM®)No ;
Temperature probeNTC 30 kΩ ;
For portable meterNo ;
Signal typeAnalog ;
SampleLow-ion strength (pure water) ;
Shaft length120 mm ;
Low MaintenanceYes ;
Material No.: 30014094
Measuring range0.001 – 500 µS/cm ;
Temperature range0 °C ; 100 °C ;
ConnectorMini-DIN ;
Cell type2 steel poles ;
Cell Constant0.105 cm-1 ;
Shaft MaterialStainless Steel ;
Shaft Diameter12 mm ;
Cable1.2 m ;
ParameterConductivity ;
Intelligent Sensor Management (ISM®)Yes ;
Temperature probeNTC 30 kΩ ;
For portable meterNo ;
Signal typeAnalog ;
SampleLow-ion strength (pure water) ;
Shaft length120 mm ;
Low MaintenanceYes ;
Material No.: 51344126
Measuring range0.001 – 500 µS/cm ;
Temperature range0 °C ; 100 °C ;
ConnectorLTW (IP67) ;
Cell type2 steel poles ;
Cell Constant0.105 cm-1 ;
Shaft MaterialStainless Steel ;
Shaft Diameter12 mm ;
Cable1.8 m ;
ParameterConductivity ;
Intelligent Sensor Management (ISM®)No ;
Temperature probeNTC 30 kΩ ;
For portable meterYes ;
Signal typeAnalog ;
SampleLow-ion strength (pure water) ;
Shaft length120 mm ;
Low Maintenance
Material No.: 51344128
Measuring range0.001 – 500 µS/cm ;
Temperature range0 °C ; 100 °C ;
ConnectorLTW (IP67) ;
Cell type2 steel poles ;
Cell Constant0.105 cm-1 ;
Shaft MaterialStainless Steel ;
Shaft Diameter12 mm ;
Cable5 m ;
ParameterConductivity ;
Intelligent Sensor Management (ISM®)No ;
Temperature probeNTC 30 kΩ ;
For portable meterYes ;
Signal typeAnalog ;
SampleLow-ion strength (pure water) ;
Shaft length120 mm ;
Low Maintenance
Material No.: 51344116
Measuring range0.001 – 500 µS/cm ;
Temperature range0 °C ; 100 °C ;
ConnectorLTW (IP67) ;
Cell type2 steel poles ;
Cell Constant0.105 cm-1 ;
Shaft MaterialStainless Steel ;
Shaft Diameter12 mm ;
Cable1.8 m ;
ParameterConductivity ;
Intelligent Sensor Management (ISM®)Yes ;
Temperature probeNTC 30 kΩ ;
For portable meterYes ;
Signal typeAnalog ;
SampleLow-ion strength (pure water) ;
Shaft length120 mm ;
Low Maintenance
Material No.: 51344030
Measuring range0.01 – 100 mS/cm ;
Temperature range0 °C ; 100 °C ;
ConnectorMini-DIN ;
Cell type2 platinum poles ;
Cell Constant1.0 cm-1 ;
Shaft MaterialGlass ;
Shaft Diameter4 mm ;
Cable1.2 m ;
ParameterConductivity ;
Intelligent Sensor Management (ISM®)No ;
Temperature probeNTC 30 kΩ ;
For portable meterNo ;
Signal typeAnalog ;
SampleSmall samples ;
Shaft length120 mm ;
Low MaintenanceYes ;
Material No.: 51344031
Measuring range0.01 – 112 mS/cm ;
Temperature range0 °C ; 100 °C ;
ConnectorMini-DIN ;
Cell type2 platinum poles ;
Cell Constant1.0 cm-1 ;
Shaft MaterialGlass ;
Shaft Diameter6 mm ;
Cable1.2 m ;
ParameterConductivity ;
Intelligent Sensor Management (ISM®)No ;
Temperature probeNTC 30 kΩ ;
For portable meterNo ;
Signal typeAnalog ;
SampleSmall samples ;
Shaft length180 mm ;
Low MaintenanceYes ;
Material No.: 51340266
Measuring range0.1 – 200 µS/cm ;
Temperature range-5 °C ; 100 °C ;
ConnectorMini-DIN ;
Cell type2 platinum poles ;
Cell Constant-- ;
Shaft MaterialEpoxy ;
Shaft Diameter12 mm ;
Cable1.2 m ;
ParameterConductivity ;
Intelligent Sensor Management (ISM®)No ;
Temperature probeNTC 30 kΩ ;
For portable meterNo ;
Signal typeAnalog ;
SampleTitration ;
Shaft length120 mm ;
Low Maintenance
Material No.: 30014160
Measuring range0.1 – 500 µS/cm ;
Temperature range0 °C ; 100 °C ;
ConnectorMini-DIN ;
Cell type2 platinum poles ;
Cell Constant0.1 cm-1 ;
Shaft MaterialGlass ;
Shaft Diameter12 mm ;
Cable1.2 m ;
ParameterConductivity ;
Intelligent Sensor Management (ISM®)No ;
Temperature probeNTC 30 kΩ ;
For portable meterNo ;
Signal typeAnalog ;
Samplenon-aquous samples ;
Shaft length120 mm ;
Low MaintenanceYes ;
Material No.: 51344112
Measuring range0.01 – 1000 mS/cm ;
Temperature range0 °C ; 100 °C ;
ConnectorLTW (IP67) ;
Cell type4 graphite poles ;
Cell Constant0.57 cm-1 ;
Shaft MaterialEpoxy ;
Shaft Diameter12 mm ;
Cable5 m ;
ParameterConductivity ;
Intelligent Sensor Management (ISM®)Yes ;
Temperature probeNTC 30 kΩ ;
For portable meterYes ;
Signal typeAnalog ;
SampleGeneral Purpose ;
Shaft length120 mm ;
Low MaintenanceYes ;
Material No.: 30014097
Measuring range0.0001 – 1000 µS/cm ;
Temperature range0 °C ; 100 °C ;
ConnectorMini-LTW (IP67) ;
Cell type2 titanium poles ;
Cell Constant0.01 cm-1 ;
Shaft MaterialTitanium ;
Shaft Diameter12 mm ;
Cable1.8 m ;
ParameterConductivity ;
Intelligent Sensor Management (ISM®)Yes ;
Temperature probePt1000 ;
For portable meterNo ;
Signal typeDigital ;
SampleLow-ion strength (pure water) ;
Shaft length67 mm ;
Low MaintenanceYes ;
Material No.: 30014099
Measuring range0.0001 – 1000 µS/cm ;
Temperature range0 °C ; 100 °C ;
ConnectorMini-LTW (IP67) ;
Cell type2 titanium poles ;
Cell Constant0.01 cm-1 ;
Shaft MaterialTitanium ;
Shaft Diameter12 mm ;
Cable1.8 m ;
ParameterConductivity ;
Intelligent Sensor Management (ISM®)Yes ;
Temperature probePt1000 ;
For portable meterNo ;
Signal typeDigital ;
SampleLow-ion strength (pure water) ;
Shaft length67 mm ;
Low MaintenanceYes ;
Comparison

Documentation

Product Brochures

InLab® Sensors
The manufacturing of high quality sensors with outstanding performance not only requires technical skills and expertise but also a profound understand...

Manuals

Operating Instructions InLab 73x_74x
Operating Instructions InLab 73x_74x

Competence

conductivity measurement
Receive a free copy of the Conductivity Measurement Theory Guide and learn the definition of conductivity and all the important basics that are necess...
USP 645 conductivity
USP 645 compliance is required for many pharma applications. Read this article and learn how to follow USP 645 for conductivity measurements in 3 easy...
Reducing Common Errors in Conductivity Measurement
Conductivity measurement using electrochemical cells is a simple and cost-effective method used to determine the concentration of dissolved substances...

FAQ

How to store conductivity sensors correctly?

All user manuals come with the necessary information about the short and long term storage of the respective sensor. Generally conductivity sensors should be stored dry for long term storage.

Why does the conductivity calibration work with just one point calibration?

Most customers measure conductivity in a quite narrow range, e.g. always the same beverage or always deionized water. With a 1-point calibration the range between 0 µS/cm and this calibration point is calibrated. Therefore, it is useful to choose a standard with higher conductivity than the expected value in the sample, e.g. 1413 µS/cm when expecting 1200 mS/cm. Performing a second calibration point in this example would not remarkably change the reading because the adjacent standards 500 µS/cm and 12.88 mS/cm are both quite far away.  

A multi-point conductivity calibration is only useful when using the same sensor over a wide range, for example from 50 to 5000 µS/cm. In this case a suitable set of standards will be 84 µS/cm, 1413 µS/cm and 12.88 mS.

According to Method 2510B in Standard Methods for the Examination of Water and Wastewater and ASTM D1125, a one-point calibration of the cell constant at a representative conductivity is sufficient for accurate conductivity readings.

How is the temperature compensated in conductivity measurement?

There are several ways of temperature compensation.

Conductivity in aqueous solution is highly affected by temperature (~2 %/°C). That’s why it is conventional to link every measurement with a reference temperature. 20 °C or 25 °C are the commonly used reference temperatures in the world of conductivity measurement.

Different temperature correction methods have been developed to suit different users:

  • Linear: for medium and highly conductive solutions
  • Non-linear: natural waters such as ground water, surface water, drinking water, and waste water
  • Pure water: ultrapure water, deionized water, distilled water
  • None: some standards such as USP <645> prohibit any temperature compensation

The impact of temperature on different ions, and even varying concentrations of the same ion, can be a challenge. Hence, for each type of sample a compensation factor, which is called temperature coefficient (α), has to be determined. (This is also the case for the calibration standards. All Mettler-Toledo meters are able to automatically account for this compensation by the use of preset temperature tables.)

What is the expected lifetime of a conductivity sensor (esp. InLab 741 and 742)?

Conductivity sensors have no expiration date. When the sensor is used within the specified temperature limits and neither severe mechanical force nor harsh chemical conditions are applied to the sensor and its cable, it can theoretically be used forever. Nevertheless, shifts of the cell constant may take place, due to deposits of fatty substances and precipitates. In most of these cases rinsing with ethanol, isopropyl alcohol or acetone can restore the sensor.

Which conductivity sensors have a nominal or certified cell constant?

InLab® 741, InLab 742 and InLab Trace come with a measured cell constant on their certificate. The cell constant of these sensors is precisely determined by the manufacturer right after production and under standardized conditions using a 100 μS/cm standard. The cell constant on the certificate can therefore be entered directly in the meter, thus making calibration with standard solutions redundant.

As these three sensors are particularly designed for use in low conducting media, such as pure water, ultrapure water, distilled water and deionized water, the measuring cell is very unlikely to be affected by contamination and hence the cell constant can be regarded as stable. Nevertheless, regular verification of the precision with a conductivity standard (e.g. 10 mS/cm) is crucial.

All other conductivity sensors from METTLER TOLEDO have nominal cell constants printed on the certificates. These sensors have to be calibrated prior to use with the appropriate calibration standard solutions.

In addition, InLab 731-ISM and InLab 738-ISM have the real cell constant stored on the ISM® chip which is used by the instruments the sensor is connected to.

How to avoid errors in conductivity measurement

The following set of tips and tricks should aid in reducing errors made in measuring conductivity:

In general, one must always make sure that the poles’ surfaces on the conductivity sensor are completely immersed in the sample solution.

Conductivity samples and standard solutions should never be diluted as the effect of dilution is not linear.

While dependent on the design of the conductivity sensor, the position of the conductivity sensor in the sample beaker can also greatly influence measuring results due to the occurrence of boundary effects outside the electrode surfaces. It is usually best to position the sensor in the middle of the beaker containing the solution.

A common source of error in conductivity measurements are air bubbles that may form on the surface of the poles. Bubbles are often not recognized by users as a source of error. They should be removed during measurement by briefly stirring the sample using a magnetic stirrer prior to measurement or, if necessary, through tapping the conductivity sensor. Successful removal of air bubbles often leads to a sudden jump in conductivity.

Since the accuracy of any measurement depends on proper calibration, a fresh standard must always be used. Ideally, sample beakers and sensor should be rinsed two to three times with the sample as the presence of contaminants can lead to additional errors in conductivity results.

Lastly, samples with low conductivities, such as pure or ultra-pure water samples, should be measured in a flow cell. Carbon dioxide dissolves in water, forming carbonic acid, which leads to higher than actual conductivity values. The flow cell ensures that atmospheric CO2 does not get into contact with low-conductivity samples and standards. This applies for both calibration and subsequent measurement. The flow cell and tubing must be thoroughly rinsed prior to use.

Know the Risk of Your pH Measurement
Ion Selective Electrode Guide – Theory and Practice
How to Measure pH in Small Samples
pH Toolbox for Life Sciences
pH Theorie Guide
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