ISO 25242:2026

ISO 25242 is an International Standard published by ISO for smart textiles systems. It specifies a test method for cyclic environmental temperature change so engineers can check how products such as electrically heated garments behave when exposed to rapid changes in ambient temperature. The document is written for systems that include the electrically operating part.

What does ISO 25242 specify?

ISO 25242 specifies an environmental test for smart textiles systems, including items such as jackets, vests and jumpers that contain an electrically operating part. The purpose is to assess whether the system can withstand repeated changes between high and low ambient temperature.

The document is organized into clauses on scope, normative references, terms and definitions, test equipment, general requirements, the test procedure, and the test report. Clause 6 carries the main method, and it covers specimen preparation, chamber preparation, mounting, conditioning, cycling, run-time measurements, recovery, and calculation of the run-time change rate.

What are the key requirements of ISO 25242?

ISO 25242 focuses on how to prepare the specimen, how to run the temperature cycle, and how to record run-time before, during, and after the test. In practice, this means the same smart textile system is checked under controlled conditions so its performance can be compared before and after thermal stress.

Test equipment and test setup

• Clause 4 requires an environmental chamber in accordance with IEC 60068-2-14 test Na or Nc. The chamber must fit the specimen, allow measurement during conditioning, and keep the temperature within the stated tolerances.
• Clause 5 requires the operating instructions and all parts needed for connection to be available for testing. Unless another specification says otherwise, all parts are connected, so the test reflects the usable system rather than a partial assembly.

Specimen preparation and temperature cycling

• Clause 6.3 requires the specimen to be tested in the unpacked, switched-off, ready-for-use state, or as otherwise specified, and three test specimens per sample are tested. This gives repeatable results across multiple specimens.
• Clause 6.6 conditions the specimen and chamber at laboratory ambient in the standard atmosphere of ISO 139 before the test, and the specimen is brought into operating condition if required. This matters because starting condition affects run-time.
• Clause 6.8 exposes the specimen to alternating high and low temperatures with defined transfers between them. If two chambers are used, test Na is preferred; if one chamber is used, test Na or Nc applies, and Nc is for water or liquid only when the sample is sealed or inherently insensitive to water.

Measurements, recovery, and result reporting

• Clauses 6.7, 6.9 and 6.11 require visual examination and electrical checking as specified, plus initial, in-operation, and finished run-time measurements on three specimens with averaging. If a specimen does not work normally after the test, the finished run-time is not calculated.
• Clause 6.10 requires recovery for at least 24 h in the standard atmosphere of ISO 139 before the finished measurement, unless a relevant specification sets a different recovery period.
• Clause 6.12 calculates the run-time change rate from the initial and finished run-time. If no finished run-time is obtained, the change rate is not reported.

What terms does ISO 25242 define?

• Smart textile system - A fabric that shows an intended and usable response to changes in its surroundings/environment or to an external signal/input.
• Initial run-time (t_initial) - The elapsed time from starting the system with a fully charged auxiliary battery integrated into the textile-based system until battery discharge stops it.
• In operation run-time (t_in operation) - The elapsed time to battery discharge measured while the test is in progress.
• Finished run-time (t_final) - The elapsed time to battery discharge measured after the test has been conducted.

Who uses ISO 25242?

ISO 25242 is used by manufacturers, test laboratories, quality managers, and buyers working with smart textiles systems and electrically heated garments. It is also relevant to product developers and technical specifiers who need to verify how a jacket, vest, jumper, or similar item behaves when temperature changes quickly. In practice, they use it to choose the test type, prepare specimens, measure run-time, and document the result.

Which standards are used with ISO 25242?

• ISO 139 - Provides the standard atmospheres used for conditioning the specimen and for recovery after the cycling test.
• IEC 60068-2-14:2023 - Provides the environmental temperature-change test methods used by ISO 25242, including test Na and test Nc, and the chamber preparation approach.
• ISO/TR 23383:2020 - Supplies the referenced definition of smart textile system used in clause 3.

What does the ISO 25242 document contain?

ISO 25242 contains the test method itself, not just a high-level statement of purpose. It includes the equipment requirements, the general testing conditions, the detailed procedure, and the reporting items needed to describe the test clearly.

Clause 6 includes the selection guidance for test Na or Nc, the specimen preparation steps, chamber preparation, mounting or supporting, conditioning, the initial run-time measurement, the temperature cycle, the in-operation run-time measurement, recovery, the finished run-time measurement, and the rate-of-change formula. Table 1 sets the main test parameters, Figure 1 illustrates the cycle, and Formula (1) gives the run-time change rate. Clause 7 lists the information to include in the test report for traceability and comparison.