Conductivity Meters

A conductivity meter is an electronic device used to measure the electrical conductivity of a solution.  It is commonly used in scientific and industrial applications to determine the concentration or purity of a solution.

When measuring conductivity, a voltage is applied across two electrodes placed in the solution. The electric current between them is then measured, and the magnitude of the current is directly related to the ions present in the solution.

To know more about conductivity and its applications, download our conductivity guide now: Conductivity Measurement Theory Guide | METTLER TOLEDO (mt.com)

A conductivity meter works by measuring the ability of a solution to conduct electricity, which is directly related to the concentration of ions in the solution. To achieve this, the meter applies a voltage across two electrodes with opposite charges in the conductivity sensor and then measures the conductance (movement of ions) between these electrodes. This conductance measurement provides a reading of the solution's conductivity.

To calibrate a conductivity meter, you will need a standard solution of known conductivity. The calibration or verification should be performed under the same conditions as the conductivity measurement (e.g., stirred/not stirred, flow cell) with the conductivity standard in a similar concentration range. You should follow these steps to calibrate your conductivity meter correctly:

1. Fill a clean beaker with a fresh standard solution. Rinse the beaker with distilled water and then wash it once with the standard solution.
2. Immerse the conductivity probe into the solution. The measuring cell must be completely immersed.
3. Eliminate the formation of any air bubbles and their entry into the measuring cell.
4. Adjust the conductivity meter until the meter reading matches the known conductivity of the solution.
5. Repeat steps 2-3 for each standard solution you use.
6. Dispose of any used standards and avoid pouring them back into the original bottle.
   

Once you have calibrated the conductivity meter, it is ready to measure other solutions' conductivity.

A conductivity meter should be calibrated regularly, typically once per day or once per week, depending on the frequency of use and the application.

Here are the general steps to use a conductivity meter:

1. Turn on the meter.
2. Calibrate the meter according to the manufacturer's instructions using a calibration standard solution.
3. Mix the solution thoroughly to ensure an even distribution of ions.
4. Dip the electrode into the solution, ensuring it is fully submerged.
5. Wait for the meter reading to stabilize; this indicates a steady-state measurement of conductivity.
6. Record the conductivity measurement displayed on the meter.
7. Rinse the electrode with distilled water and dry it with a clean towel.
8. Turn off the meter.

Additional features of conductivity meters may include temperature compensation, automatic range selection, and data logging. These features may require additional steps for proper use.

For more comprehensive guidance on how to use a METTLER TOLEDO conductivity meter, download our Conductivity Measurement Theory Guide.

The cell constant is a crucial parameter in conductivity measurement and represents the relationship between the conductivity of a cell's geometry and a solution's measured conductivity.

It is defined as the ratio of the distance between the two electrodes to the effective area of the electrodes.

The cell constant is used to convert the measured conductance (reciprocal of resistance) into the actual conductivity of the solution. It allows the conductivity meter to accurately determine the conductivity of a solution based on the electrical conductance measured between the electrodes.

The cell constant can vary depending on the design and construction of the conductivity cell. Therefore, it's essential to know the specific cell constant for the conductivity cell being used to obtain accurate conductivity measurements.

For detailed information about cell constants, please refer to the specific section in our Conductivity Measurement Theory Guide.

METTLER TOLEDO uses two kinds of cell constants: nominal and certified. Sensors with a nominal cell constant must be calibrated before the first use, while sensors with a known cell constant only require verification.

Certified cell constants are determined directly at the plant after the manufacturing process. With a maximum uncertainty of ± 2%, they are accurate enough and can be used for measurement.

To ensure accurate conductivity measurement, it is recommended to verify the cell constant before testing. This can be achieved by measuring the conductivity of a standard solution and checking if the reading falls within the predefined limits (typically ±2% of the standard solution).

For details, refer to our conductivity theory guide: Conductivity Measurement Theory Guide | METTLER TOLEDO (mt.com)

The purpose of calibrating a conductivity meter is to ensure that it provides accurate and reliable readings. It is recommended to calibrate your conductivity meter regularly because its accuracy can be affected by various factors such as temperature, age, and electrode wear and tear.

No, a conductivity meter cannot measure pH directly. Conductivity and pH are two distinct properties of a solution and require different measuring techniques and instruments.

Conductivity meters are used to measure a solution's ability to conduct electricity, whereas pH meters measure the acidity or alkalinity of a solution based on its hydrogen ion concentration. However, some conductivity meters have a feature that enables them to measure pH and conductivity simultaneously. This is typically known as a multi-parameter meter but requires separate electrodes for each parameter.

METTLER TOLEDO offers the SevenExcellence pH/Cond meter S470 that can measure pH and conductivity simultaneously. This feature is particularly beneficial for laboratories that need both measurements in their routine analysis. By using this all-in-one solution, your laboratory can enhance its processes and achieve reliable and precise results every time.

The accuracy of a conductivity meter is not determined by its electrode alone; it's a function of the entire measuring system, including the meter.

Several factors affect the accuracy of a conductivity measurement, such as the condition and age of the electrode, the electronics of the instrument, the temperature probe, and the accuracy of the calibration, amongst other factors. Across the system, we can expect a measuring accuracy of ±2% (meter accuracy: ±0.5%).

Conductivity meters are used in a wide range of applications where measuring the electrical conductivity of a solution is essential. Here are some of the typical applications of conductivity meters:

• Water quality analysis
• Salinity 
• TDS 
• Industrial process control 
• Scientific research 

Conductivity meters are often used for quality control, process optimization, and regulatory compliance.

SI unit for conductivity is Siemens per meter (S/m); however, micro-siemens per centimeter (μS/cm) is a commonly used unit for expressing conductivity, especially in laboratory and industrial settings. One micro-siemens per centimeter is equal to 0.01 milli-siemens per centimeter.

In addition to conductivity, some conductivity meters can also provide measurements for Total Dissolved Solids (TDS), salinity, resistivity, and bioethanol.

The range of a conductivity meter depends on the specific model, the manufacturer, and the type of electrode or probe being used. Most modern conductivity meters measure a wide range, from microsiemens per centimeter (µS/cm) to Siemens per meter (S/m).

Our Seven series conductivity meters have a measuring range of 0.001 μS/cm to 2000 mS/cm, but this range can differ from model to model. To find out the exact conductivity range for each model, refer to the respective datasheets. Also, keep in mind that the conductivity range can vary with each sensor. For more information, please refer to the product brochure for sensors.

A conductivity meter and a TDS (total dissolved solids) meter are both used to measure the concentration of ions in a solution. However, there are some differences between the two.

A conductivity meter measures the ability of a solution to conduct electricity, which is directly related to the concentration of ions in the solution. The meter works by measuring the electrical conductivity of a sample and then converting it into a conductivity value.

A TDS meter, on the other hand, measures the concentration of dissolved solids in a solution, including both inorganic and organic substances. It does so by calculating the electrical conductivity of the solution and converting it into a TDS measurement.