Conductivity Sensor: For a Wide Range of Specific Applications

Conductivity Sensor

High Accuracy for a Wide Measuring Range

Meters

pH Meters

To fit your electrochemistry system needs, we offer a variety of benchtop and portable meters that are professional and durable. Our portfolio offers products designed for compliance, routine measurements or anyone working on a tight budget.

Benchtop MetersPortable Meters

Solutions

pH Solutions

METTLER TOLEDO offers a comprehensive range of top quality buffers, standards, electrolytes, cleaning and verification solutions for determination of pH, conductivity, ion concentration, ORP and dissolved oxygen. All solutions are available in small volume bottles either in packs or single and single use sachets.

More about Solutions

Service

Service for pH meters and sensors

We offer different service packages depending on your needs. These range from professional on-site installation and configuration to documented proof of compliancy. If full coverage beyond initial warranty is desired, we offer an extended care package in the form of preventive maintenance and repair.

More about Service
 
Analytical Instruments

Products and Specs

 
Products and Specs
Filter:
Set filter
Clear All
 
Connector
Cell type
Cell Constant
Shaft Material
Shaft Diameter
Material No.: 51302256
See details
ConnectorMini-DIN
Cell type4 platinum poles
Cell Constant0.80 cm-1
Shaft MaterialGlass
Shaft Diameter12 mm
For portable meterNo
SampleHigh-ion strength
Material No.: 51302255
See details
ConnectorMini-DIN
Cell type2 platinum poles
Cell Constant0.06 cm-1
Shaft MaterialGlass
Shaft Diameter12 mm
For portable meterNo
Samplenon-aquous samples
Material No.: 30014160
See details
ConnectorMini-DIN
Cell type2 platinum poles
Cell Constant0.1 cm-1
Shaft MaterialGlass
Shaft Diameter12 mm
For portable meterNo
Samplenon-aquous samples
Material No.: 51344020
See details
ConnectorMini-DIN
Cell type4 graphite poles
Cell Constant0.57 cm-1
Shaft MaterialEpoxy
Shaft Diameter12 mm
For portable meterNo
SampleGeneral Purpose
Material No.: 30014092
See details
ConnectorMini-DIN
Cell type4 graphite poles
Cell Constant0.57 cm-1
Shaft MaterialEpoxy
Shaft Diameter12 mm
For portable meterNo
SampleGeneral Purpose
Material No.: 51344022
See details
ConnectorMini-DIN
Cell type4 graphite poles
Cell Constant0.57 cm-1
Shaft MaterialEpoxy
Shaft Diameter12 mm
For portable meterNo
SampleGeneral Purpose
Material No.: 30014093
See details
ConnectorMini-DIN
Cell type4 graphite poles
Cell Constant0.57 cm-1
Shaft MaterialEpoxy
Shaft Diameter12 mm
For portable meterNo
SampleGeneral Purpose
Material No.: 51344030
See details
ConnectorMini-DIN
Cell type2 platinum poles
Cell Constant1.0 cm-1
Shaft MaterialGlass
Shaft Diameter4 mm
For portable meterNo
SampleSmall samples
Material No.: 51344031
See details
ConnectorMini-DIN
Cell type2 platinum poles
Cell Constant1.0 cm-1
Shaft MaterialGlass
Shaft Diameter6 mm
For portable meterNo
SampleSmall samples
Material No.: 51344024
See details
ConnectorMini-DIN
Cell type2 steel poles
Cell Constant0.105 cm-1
Shaft MaterialStainless Steel
Shaft Diameter12 mm
For portable meterNo
SampleLow-ion strength (pure water)
Material No.: 30014094
See details
ConnectorMini-DIN
Cell type2 steel poles
Cell Constant0.105 cm-1
Shaft MaterialStainless Steel
Shaft Diameter12 mm
For portable meterNo
SampleLow-ion strength (pure water)
Material No.: 51344026
See details
ConnectorMini-DIN
Cell type2 steel poles
Cell Constant0.105 cm-1
Shaft MaterialStainless Steel
Shaft Diameter12 mm
For portable meterNo
SampleLow-ion strength (pure water)
Material No.: 30014097
See details
ConnectorMini-LTW (IP67)
Cell type2 titanium poles
Cell Constant0.01 cm-1
Shaft MaterialTitanium
Shaft Diameter12 mm
For portable meterNo
SampleLow-ion strength (pure water)
Material No.: 30014099
See details
ConnectorMini-LTW (IP67)
Cell type2 titanium poles
Cell Constant0.01 cm-1
Shaft MaterialTitanium
Shaft Diameter12 mm
For portable meterNo
SampleLow-ion strength (pure water)
Material No.: 51344120
See details
ConnectorLTW (IP67)
Cell type4 graphite poles
Cell Constant0.57 cm-1
Shaft MaterialEpoxy
Shaft Diameter12 mm
For portable meterYes
SampleGeneral Purpose
Material No.: 51344122
See details
ConnectorLTW (IP67)
Cell type4 graphite poles
Cell Constant0.57 cm-1
Shaft MaterialEpoxy
Shaft Diameter12 mm
For portable meterYes
SampleGeneral Purpose
Material No.: 51344124
See details
ConnectorLTW (IP67)
Cell type4 graphite poles
Cell Constant0.57 cm-1
Shaft MaterialEpoxy
Shaft Diameter12 mm
For portable meterYes
SampleGeneral Purpose
Material No.: 51344110
See details
ConnectorLTW (IP67)
Cell type4 graphite poles
Cell Constant0.57 cm-1
Shaft MaterialEpoxy
Shaft Diameter12 mm
For portable meterYes
SampleGeneral Purpose
Material No.: 51344112
See details
ConnectorLTW (IP67)
Cell type4 graphite poles
Cell Constant0.57 cm-1
Shaft MaterialEpoxy
Shaft Diameter12 mm
For portable meterYes
SampleGeneral Purpose
Material No.: 51344114
See details
ConnectorLTW (IP67)
Cell type4 graphite poles
Cell Constant0.57 cm-1
Shaft MaterialEpoxy
Shaft Diameter12 mm
For portable meterYes
SampleGeneral Purpose
Material No.: 51344126
See details
ConnectorLTW (IP67)
Cell type2 steel poles
Cell Constant0.105 cm-1
Shaft MaterialStainless Steel
Shaft Diameter12 mm
For portable meterYes
SampleLow-ion strength (pure water)
Material No.: 51344128
See details
ConnectorLTW (IP67)
Cell type2 steel poles
Cell Constant0.105 cm-1
Shaft MaterialStainless Steel
Shaft Diameter12 mm
For portable meterYes
SampleLow-ion strength (pure water)
Material No.: 51344116
See details
ConnectorLTW (IP67)
Cell type2 steel poles
Cell Constant0.105 cm-1
Shaft MaterialStainless Steel
Shaft Diameter12 mm
For portable meterYes
SampleLow-ion strength (pure water)
Material No.: 51344118
See details
ConnectorLTW (IP67)
Cell type2 steel poles
Cell Constant0.105 cm-1
Shaft MaterialStainless Steel
Shaft Diameter12 mm
For portable meterYes
SampleLow-ion strength (pure water)
Material No.: 51302885
See details
ConnectorMini-DIN
Cell type4 platinum poles
Cell Constant--
Shaft MaterialEpoxy
Shaft Diameter7 mm
For portable meterNo
Material No.: 51302401
See details
ConnectorMini-DIN
Cell type4 platinum poles
Cell Constant--
Shaft MaterialEpoxy
Shaft Diameter12 mm
For portable meterNo
Material No.: 51340266
See details
ConnectorMini-DIN
Cell type2 platinum poles
Cell Constant--
Shaft MaterialEpoxy
Shaft Diameter12 mm
For portable meterNo
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
A description of the USP requirements and instrumentation specifications for conductivity measurements in purified water. Tips and tricks on how to m...
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...

Services

(Toll Free) 1800 22 8884 & 1800 1028 460
Call Service

Explore our Services - Tailored to Fit your Equipment

We support and service your measurement equipment through its entire life-cycle, from installation to preventive maintenance and calibration to equipment repair.

Performance
Maintenance & Optimization
Expertise
Training & Consulting

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.

Join the GEP eLearning Program
Know the Risk of Your pH Measurement
pH Theorie Guide
pH Toolbox for Life Sciences
 
 
 
 
 
 
 
Thank you for visiting www.mt.com. We have tried to optimize your experience while on the site, but we noticed that you are using an older version of a web browser. We would like to let you know that some features on the site may not be available or may not work as nicely as they would on a newer browser version. If you would like to take full advantage of the site, please update your web browser to help improve your experience while browsing www.mt.com.