When a product is submitted for testing, it can be tempting to think that the “real” test begins when the equipment is switched on, the load is applied, the leakage is measured, or the performance requirement is assessed.
In many European product standards, however, an important step comes first: climatic conditioning.
For an ISO 17025 accredited testing laboratory, climatic conditioning is not just a box-ticking exercise. It is a controlled and traceable way of preparing test specimens so that the results reflect how a product may perform after exposure to real environmental conditions such as heat, cold, humidity, dryness, storage, transport, or use.
What is climatic conditioning?
Climatic conditioning is the process of exposing a product, component, or test specimen to defined environmental conditions before carrying out further testing. Those conditions usually include three things:
- Temperature
- Relative humidity
- Duration of exposure
In the respiratory protective device test method BS EN 13274-5:2001, climatic conditioning is specifically described as a combination of these three parameters. The standard gives an example of a conditioning phase as 30 °C, wet atmosphere, for 24 hours. It also explains that a full cycle may consist of one or more phases.
In simple terms, conditioning asks: how does the product perform after it has been exposed to the environment it may experience before or during use?
Why is climatic conditioning done before other testing?
Many product standards require conditioning before performance testing because materials and assemblies can change when exposed to different climates. For example:
- Plastics can become more brittle in cold conditions.
- Elastomeric seals can soften, harden, swell, or lose flexibility.
- Adhesives and bonds can be affected by heat or moisture.
- Filters and porous materials may respond differently after exposure to humidity.
- Straps, harnesses, valves, facepieces, packaging, and other components may behave differently after storage or environmental stress.
If a product only passes when it is tested straight out of the box at comfortable room temperature, that may not be enough. Users rarely operate products in ideal laboratory conditions. Products may be stored in vehicles, warehouses, containers, hospitals, industrial sites, emergency response kits, or outdoor environments. Climatic conditioning helps reveal whether the product still performs after those exposures.
Conditioning helps make testing fair, repeatable, and meaningful
A key purpose of standardised testing is comparability. If one laboratory tests a product immediately after unpacking it, another tests it after 24 hours in a humid chamber, and another tests it after exposure to heat, the results may not be comparable.
This is why test standards define conditioning requirements.
BS EN 13274-5 sets out that the relevant product or device standard must specify important details such as:
- the items to be tested;
- the number of specimens;
- the conditioning phases to be used;
- the sequence of phases where more than one is required;
- any observations to be made;
- the orientation and position of the specimen during conditioning;
- whether the specimen is packaged, sealed, or fully assembled.
This matters because the way a sample is conditioned can directly affect the outcome. A fully assembled product may respond differently from an individual component. A packaged product may be protected from humidity in a way an unpackaged product is not. A specimen placed under load or touching another specimen may not be exposed evenly.
For accredited laboratories, these details are critical because they support technical validity, repeatability, and confidence in the final test result.
Examples of climatic conditions in BS EN 13274-5
BS EN 13274-5 is a test method for respiratory protective devices, but the principles behind it are widely relevant across many product sectors.
The standard defines several environmental categories, including:
- Ambient conditions: 16 °C to 32 °C with relative humidity of 50 ± 30%.
- Dry atmosphere: relative humidity below 20%.
- Wet atmosphere: relative humidity greater than or equal to 95%.
The standard also provides a range of temperatures that can be selected for conditioning, including:
- 70 ± 3 °C;
- 60 ± 3 °C;
- ambient temperature between 16 °C and 32 °C;
- -6 ± 3 °C;
- -15 ± 3 °C;
- -30 ± 3 °C;
- or the manufacturer’s highest or lowest recommended temperature.
Exposure durations can also vary. The standard lists options including 72 hours, 24 hours, 17 hours, more than 12 hours, 10 hours, more than 4 hours, and 3 hours, each with the specified tolerances where applicable.
These examples show that climatic conditioning is not a single fixed treatment. It is a controlled process selected according to the relevant product standard and the intended purpose of the test.
Avoiding thermal shock
One important detail in BS EN 13274-5 is the requirement to avoid thermal shock. The standard states that, during conditioning, the temperature gradient must be less than 2°C per minute between phases at different temperatures, or between the start and end of a thermal cycle.
This is important because the aim is usually to assess the effect of specified climatic exposure, not to introduce uncontrolled damage caused by sudden temperature change.
For example, moving a specimen instantly from a very hot chamber to a very cold chamber could create stresses that are not representative of the intended conditioning regime. A controlled transition helps ensure that the conditioning process remains consistent with the test method.
Why specimen placement matters
Climatic conditioning is not only about chamber settings. The way specimens are placed inside the chamber is also important.
BS EN 13274-5 requires specimens to be positioned so that air can circulate freely around them. It also states that components should not have their weight supported by another component unless that is specifically intended by the manufacturer, and separate specimens should not touch.
This is a practical but crucial point. If samples are stacked, touching, shaded from airflow, or distorted by their own weight, they may not all experience the same conditions. That can affect repeatability and may compromise the validity of subsequent testing.
Good conditioning practice therefore requires:
- suitable chamber loading;
- adequate spacing between specimens;
- controlled orientation;
- documented sample condition;
- stable temperature and humidity monitoring;
- clear traceability to the relevant test method.
- What can climatic conditioning reveal?
Climatic conditioning can expose weaknesses that may not be obvious under normal laboratory conditions.
Depending on the product type, it may reveal:
- loss of flexibility after cold exposure;
- deformation after heat exposure;
- seal leakage after humidity exposure;
- deterioration of straps, gaskets, valves, or adhesives;
- filter performance changes after moisture exposure;
- packaging or storage vulnerabilities;
- dimensional or mechanical instability;
- changes in fit, function, or usability.
For respiratory protective devices, these effects can be safety critical. A facepiece, valve, filter, or seal must continue to function after the environmental exposures required by the relevant product standard. That is why BS EN 13274-5 exists as a supporting test method for respiratory protective device standards. It is intended to supplement specific device standards, which define when and how the conditioning is to be applied.
Why this matters for manufacturers
For manufacturers, climatic conditioning provides evidence that a product has been assessed beyond ideal conditions. It can support:
- product development;
- conformity assessment;
- CE/UKCA technical documentation;
- quality investigations;
- comparison of materials or suppliers;
- validation of storage and use claims;
- confidence in product robustness.
It can also help identify issues early. Finding that a component fails after humidity exposure during development is far better than discovering the problem after production, certification, or field use.
Why this matters for end users
For end users, climatic conditioning helps provide confidence that tested products are not only capable of passing in a controlled laboratory environment, but have also been assessed after defined environmental exposure.
This is especially important for safety-related products. In real life, equipment may be stored in warm warehouses, cold vehicles, damp environments, or changing seasonal conditions before it is used.
Climatic conditioning helps answer a simple but important question: Will the product still perform after the environment has had a chance to affect it?
The role of an ISO 17025 accredited laboratory
In an accredited testing laboratory, climatic conditioning must be carried out with control, competence, and traceability. That means ensuring that:
- the correct conditioning regime is selected from the applicable product standard;
- chamber temperature and humidity are monitored and recorded;
- tolerances are understood and applied correctly;
- exposure durations are controlled;
- specimens are positioned correctly;
- any required observations are documented;
- the sequence of conditioning and subsequent testing is followed;
- records are sufficient to demonstrate what was done.
This level of control is what gives meaning to the final test result. The performance test is only as reliable as the preparation that came before it.
Conclusion
Climatic conditioning is an essential part of many EN product testing programmes. It prepares specimens in a controlled way before further testing, helping to ensure that results are fair, repeatable, and relevant to real-world storage and use.
BS EN 13274-5 provides a clear example of how this is done: by defining temperature, humidity, duration, specimen placement, air circulation, and controlled transitions between conditions.
For manufacturers, it helps demonstrate product robustness. For users, it helps build confidence. For accredited laboratories, it is a key part of delivering technically valid results.
In short, climatic conditioning is not just preparation for the test, it is part of the test.