5 Common Mistakes in Temperature Mapping and How to Avoid Them

Aug 26 / Chris Maughan




Temperature mapping is a critical process in ensuring that controlled temperature chambers maintain the required conditions for stored products.

Thermal Compliance validation engineers have mapped thousands of such chambers, and we regularly encounter five common mistakes that can compromise the success of a qualification. Here’s how to avoid them:

1. Not Performing a Pre Mapping Walk Through

Performing a pre mapping walk through is a simple yet crucial step in ensuring a successful qualification.

By visiting the equipment before mapping, you can check the shelving layout, preventative maintenance logs, and record essential details such as serial numbers, site ID and location information.

Skipping this step often leads to oversights that could affect the accuracy and reliability of your temperature mapping.

2. Bespoke Protocol Generation

A well performed pre mapping walkthrough should identify any unit specific information. This will include serial numbers, IDs, Temperature ranges, Shelf Layout, storage items and any process specific information.

With this data a protocol can be generated specifically for the unit under test. For example you may add humidity, include provision for ATEX Sensors or increase the sensor locations for the maximum storage height.

3. Sensor Selection

Sensor selection can be critical to the success or failure of a temperature mapping exercise. It's important to ensure the sensor has a suitable accuracy, range and calibration for your application.

Some units require extremely precise sensors (with accuracy as tight as ±0.05°C), while others need sensors with fast response times, wireless data capabilities, or ATEX ratings for potentially explosive environments. Choosing the wrong sensor can compromise your entire mapping process.

4. Sensor Placement

Part of the consideration for your sensor selection should be, how are you going to safely and repeatably place the sensors. 

When you have suitable sensors you will need to consider how the unit performs, the useable space (from minimum to maximum storage height), where heating and cooling sources are located, and the criticality of the product being stored. 

Photographs can help in ensuring sensor placement is repeatable for future requalification. If possible the same sensor type and sensor placement techniques should be used.

5. Calibration

Whether you perform calibrations in-house or send them to an ISO 17025 Accredited Laboratory, it's vital to ensure the calibration is appropriate for the range and accuracy requirements of your sensors.

Additionally, the frequency of calibration should align with the level of risk acceptable to your organization. Ensuring the sensor is within calibration at the start of use and closing the calibration loop with an as-found calibration is essential. Delays or infrequent calibrations increase the risk of sensor damage and, consequently, qualification failures.

The calibration should include the full range of measurements expected in the qualification. If your measuring humidity it is good practice to calibration humidity at the temperature ranges of the equipment tested.

Conclusion

Avoiding these common mistakes can significantly improve the accuracy and reliability of your temperature mapping.

If you have any questions, feel free to ask me by email or in our temperature mapping community. I’m happy to help!
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