Overview
ISO 2782-2:2018 - "Rubber, vulcanized or thermoplastic - Determination of permeability to gases - Part 2: Equal-pressure method" - specifies a laboratory method to measure gas transmission rate and the gas permeability coefficient of vulcanized or thermoplastic rubber using gas chromatography (GC). The standard covers tests performed with equal overall pressure on both sides of a mounted test piece (equal-pressure method), allowing measurement of single gases or gas mixtures for rubbers of hardness ≥ 35 IRHD.
Key Topics
- Principle: A temperature-controlled test cell separates a gas supply side and a carrier-gas transmission side; partial-pressure differences drive diffusion through the rubber while overall pressures remain equal. Permeating gas is quantified by GC.
- Apparatus requirements: Test cell with defined gas transmission area (diameter typically 10–150 mm), heating system (up to 80 °C; ±1 °C accuracy from 40–80 °C), gas chromatograph with suitable detector (e.g., TCD or FID), sampling loop, and temperature sensors (readable to 0.1 °C).
- Gases and purity: Single gases (N2, O2, H2) or mixtures (air, LPG in gaseous form). Purity of components should be ≥ 99.5% unless otherwise agreed; mixtures require individual component calibration.
- Operational details: Typical carrier and test gas flow rates are within 5–100 ml/min; procedure includes purging, leak inspection, timed sampling via GC, and use of calibration curves (minimum three concentration points).
- Calibration and accuracy: Apparatus calibration per Annex A; calibration curves produced by injecting known gas quantities into the GC to convert peak area to concentration.
- Test pieces & conditioning: Specimen shape, thickness measurement, preparation, conditioning, and number of samples are referenced to ISO 2782-1 and ISO 23529.
Applications
ISO 2782-2:2018 is used for:
- Material selection and quality control in products that contain or seal gases: inner tubes, tubeless-tyre liners, hoses, balloons, diaphragms, and seals.
- R&D and comparative studies of gas diffusion and solubility in rubber compounds.
- Compliance testing where accurate gas permeability data are required for product design, lifetime estimation, or regulatory documentation.
Typical users include rubber manufacturers, independent testing laboratories, materials scientists, OEM quality engineers, and product safety teams.
Related Standards (if applicable)
- ISO 2782-1:2016 - Differential-pressure methods for gas permeability of rubber
- ISO 18899:2013 - Guide to calibration of test equipment
- ISO 23529 - Preparing and conditioning test pieces for physical test methods
Note: Users should follow normal laboratory safety practice and agree test details (e.g., purity, temperature range) with interested parties before testing.