Overview
EN ISO 2231:1995 (ISO 2231:1989) specifies standard atmospheres and conditioning methods for rubber- or plastics-coated fabrics used in laboratory testing. The standard defines required atmospheres, pre-conditioning procedures, and acceptance criteria for moisture equilibrium so that test results (mass, mechanical properties, thread breaking, etc.) are comparable and reproducible. This edition incorporates a technical revision of clauses on definitions and conditioning and introduces a dedicated pre‑conditioning clause.
Key topics and requirements
- Scope and purpose
- Applies to conditioning and methods of conditioning for coated fabrics prior to testing.
- Ensures moisture content and temperature are controlled because these affect test outcomes.
- Defined standard atmospheres
- Atmosphere A: 20 °C ± 2 °C; 65 % ± 5 % RH
- Atmosphere B: 23 °C ± 2 °C; 50 % ± 5 % RH
- Atmosphere C (tropical): 27 °C ± 2 °C; 65 % ± 5 % RH
- Atmosphere D: Temperature control only at 23 °C ± 2 °C
- Atmosphere E (tropical temp. control): Temperature control only at 27 °C ± 2 °C
- Pre-conditioning
- For highly hygroscopic substrates or when high accuracy is required, specimens should be pre-conditioned from the dry side of the hysteresis curve (≤ 10 % RH) at elevated temperature (60–70 °C) to approach equilibrium.
- Equilibrium criteria
- Moisture equilibrium is reached when successive weighings of freely exposed specimens, at 2‑hour intervals, differ by less than 0.1 %.
- Recommended minimum exposure times: 16 h for fabrics coated on one side; 24 h for both‑sided coatings.
- Methods of conditioning
- Method 1: Expose test pieces freely to Atmosphere A, B or C until equilibrium is achieved.
- Method 2: Expose test pieces freely to Atmosphere D or E for a period of 3 hours (where applicable).
- Normative reference
- ISO 554 (Standard atmospheres for conditioning and/or testing) is referenced for the standard reference atmosphere.
Applications and users
- Manufacturers of rubber‑ or plastics‑coated fabrics for quality control and product specification.
- Independent testing laboratories performing mechanical, mass or durability tests where moisture/temperature affects results.
- R&D teams validating material formulations and coating processes under controlled climates.
- Procurement and compliance teams relying on standardized test reports for acceptance criteria.
Related standards
- ISO 554 - Standard atmospheres for conditioning and/or testing (normative reference cited by EN ISO 2231).
- Any material‑ or test‑specific standards that reference designated conditioning atmospheres and methods (consult the particular test standard to choose the correct atmosphere).
Keywords: EN ISO 2231:1995, ISO 2231:1989, rubber-coated fabrics, plastics-coated fabrics, standard atmospheres, conditioning and testing, pre-conditioning, relative humidity, ISO 554.
