IEC 60068-3-6:2018 Performance Confirmation of Temperature and Humidity Chambers

IEC 60068-3-6:2018 addresses performance confirmation of temperature and humidity test chambers without specimens. It provides a reproducible approach to checking whether a chamber can deliver the climatic conditions needed for IEC 60068 environmental tests. It also supports regular chamber performance monitoring.

Chamber confirmation and product testing

Chamber confirmation asks, “Is the test environment suitable?” IEC 60068-2-78 steady-state damp heat investigates product resistance to high humidity at constant temperature without condensation. IEC 60068-2-30 cyclic damp heat involves temperature cycles and generally produces condensation on the specimen surface. Conditions for these damp heat methods are not interchangeable; composite temperature and humidity cycling is another distinct method.

Why the display is not enough

The controller usually responds to its own sensor. Calibrating that sensor does not characterize the air throughout the working space. When selecting a Pt100 or another temperature probe, a humidity sensor and a data logger, consider their measurement ranges, uncertainty and recording capabilities. Performance measurements use a system independent of the chamber controller.

Which properties need separate assessment?

A single central reading for temperature and humidity cannot describe the spatial distribution. Define the volume intended for use; the entire chamber interior is not automatically the confirmed working space. These explanations introduce the concepts; calculations follow the applicable procedure.

Preparing the measurement setup

Start with a written plan: define the working space, temperature and humidity points, sensor locations, recording interval and assessment period. Consider temperature measurement standards and the applicable procedure. Check appropriate calibration records for the sensors. Position air probes without contact with walls or shelves, and arrange cable feedthroughs so they do not compromise sealing or airflow.

Take steady-state measurements after conditions have stabilized. Synchronize channel timestamps and record sensor positions and surrounding conditions. Do not assume a universal sensor count, layout or monitoring duration for every chamber; follow the standard and the intended application.

Temperature and relative humidity belong together

Relative humidity depends on temperature. Heat conducted to a probe from outside the chamber can make its temperature differ from the surrounding air and distort the humidity result. This matters especially near condensation. Select the measurement technology and probe installation for the target conditions.

Review both the chamber's temperature range and its available temperature-humidity operating envelope. Cold, dry heat and temperature change create different requirements. Good performance at one fixed point does not, by itself, demonstrate that every transition in a temperature-change test is suitable.

What does an empty-chamber result mean with a load?

Adding a PLC, power supply or cabinet can change airflow and heat load. Empty-chamber confirmation alone does not establish loaded test conditions. IEC 60068-3-7:2020 addresses measurements in loaded temperature chambers for cold and dry heat tests; its scope should not be extended to all humidity tests.

Air temperature can also differ from the temperature inside the product. Define whether the specimen is powered and how it is positioned for its operating and storage conditions. Measure product temperature separately when it is needed.

A simple assessment example

For illustration only: if the display reads 40.0 °C and the reference-location average is 39.6 °C, the reference-minus-display difference is −0.4 °C. If readings at that location range from 39.4 to 39.8 °C, the observed maximum-minus-minimum difference is 0.4 °C. These describe different properties; the example does not replace the standard's calculation method or acceptance limits.

Acceptance decisions and reporting

IEC 60068-3-11:2007 supports uncertainty assessment for steady-state temperature and humidity conditions. Sensor calibration, the recording system and environmental variations can affect the result. State measurement uncertainty separately from acceptance limits and explain the decision rule before assessing conformity.

The report supporting environmental test selection and the overall test plan should identify the chamber, standard edition, confirmed volume, empty or loaded condition, set points, sensor positions, calibration information, timestamped records, results and assessment conditions. Set the reconfirmation interval through the use and quality plan; review the need for reassessment after significant maintenance or modifications.

Technical references: IEC 60068-3-6:2018 · IEC 60068-3-11:2007 · IEC 60068-3-7:2020 · IEC 60068-2-30:2025 · IEC 60068-2-78:2025 · PTB / DKD-R 5-7 (2025) · Vaisala: chamber mapping · Vaisala: humidity measurement