Step-by-Step Guide to Calibrate a Conductivity Analyzer

Many of you have asked for a detailed explanation on how to calibrate a conductivity analyzer, so today I’m sharing a complete walkthrough using a Model 200 Dual Channel Conductivity Controller as an example.

⚙️ Equipment Overview
This controller is a dual-channel conductivity analyzer, meaning it can simultaneously connect two conductivity sensors.

In our case, one channel reads 3.141 µS/cm, and the other reads 0.043 µS/cm.

Each channel requires its own sensor, and we will demonstrate calibration on one of them.

🔗 Components
Controller Unit: Displays and processes conductivity signals.

Conductivity Sensor: Detects the actual conductivity in the process fluid.

Cell Constant (K-Factor): Each sensor has a specified cell constant (K), usually printed on its body. For example, here the constant is 0.01 cm⁻¹.

Additionally:

Max Operating Pressure: 10 bar

Max Operating Temperature: 125°C

Temperature Compensation: PT100 sensor is integrated for automatic temperature correction.

✅ Calibration Preparation
Isolate the Sensor:

Disconnect the sensor from the process line.

Carefully remove its connector to avoid damage.

Clean & Dry the Sensor:

Perform an air purge or gentle blow-dry to ensure the electrode is completely free of process liquid.

Use a lint-free cloth or compressed air if necessary.

⚙️ Zero Calibration (Air Calibration)
Verify the sensor is completely dry.

On the controller’s setup menu, navigate to Sensor Setup → Calibration → Zero Calibration.

Confirm that the cell constant (K-value) entered in the controller matches the value on the sensor.

Example: If the sensor shows K = 0.01 cm⁻¹, update this under Cell Constant in your controller.

Save the value and proceed.

Initiate zero calibration. The analyzer should read 0 µS/cm in dry air.

If not, repeat drying and recalibrate until you get a stable zero reading.

Once the zero calibration passes, the system will display “Calibration Passed”.

⚙️ Span (Standard Solution) Calibration
Prepare a standard conductivity solution — e.g., 10 µS/cm.

Immerse the cleaned sensor in the standard solution.

Wait for the reading to stabilize — it may take a few seconds.

If the reading deviates (e.g., 10 µS/cm standard but the controller shows 10.5 µS/cm), perform the span calibration:

Navigate to Sensor Setup → Calibration → Span Calibration.

Enter the known standard value (e.g., 10 µS/cm).

Accept the new reading.

Once successful, the controller will adjust the sensor signal for accurate measurements.

📊 Post-Calibration Check
After zero and span calibration, return the sensor to the process.

Observe the live conductivity reading — verify it aligns with expected process values.

Repeat the procedure if drift persists or if a new sensor is installed.

🧩 Key Technical Tips
Always check the cell constant (K-Factor) before calibration — incorrect values lead to major measurement errors.

Keep the sensor electrodes clean and free of scaling.

Use fresh, certified standard solutions for accurate span calibration.

Allow readings to stabilize fully — do not rush the calibration steps.

For precise applications, verify the PT100 temperature sensor works properly, as temperature compensation directly affects conductivity results.

📌 Theory & Additional Notes
If you’d like a deeper explanation of the theoretical principles, standard solution preparation, or troubleshooting for non-linear cell factors, feel free to comment or reach out. I’ll be happy to make a detailed follow-up guide!

✅ Remember: Regular calibration ensures your conductivity analyzer provides accurate, reliable process measurements — which is critical for quality control, compliance, and system efficiency.