Overview
ISO 7229:2022 - Rubber- or plastics-coated fabrics - Measurement of gas permeability specifies two accepted laboratory methods for determining gas transmission through rubber- or plastics-coated fabrics, a property commonly referred to as gas permeability. The standard defines the test principle (test piece mounted in a hermetically sealed cell, vacuuming, pressurizing one side, and measuring gas passage), required test conditions and specimen preparation, and how to calculate and report gas transmission rate and gas permeability coefficient.
Key topics and technical requirements
- Two measurement methods:
- Pressure sensor method - detects pressure increase on the low-pressure side.
- Gas chromatography (GC) method - quantifies transmitted gas analytically; Annex A describes an equal-pressure GC variant.
- Specimen requirements: thickness between 0.10 mm and 4.00 mm (unless otherwise agreed); measure thickness at five or more points per ISO 2286-3; use three or more test pieces.
- Sealing and masking: edges and substrate areas must be sealed/masked (wax or non-cracking adhesive) to prevent leakage through the substrate.
- Conditioning and atmosphere: minimum 16 h between vulcanization and conditioning; standard laboratory atmosphere (23 ± 2) °C per ISO 2231; conditioning typically 16–24 h.
- Apparatus and calibration: test cell with defined gas transmission area (internal diameter 10–150 mm), vacuum pump (to ≤10 Pa), pressure sensors with resolution to at least 5 Pa, temperature control (up to 80 °C, ±2 °C at 40–80 °C), and test gas reservoirs sized to limit pressure drop on the high-pressure side to ≤1%.
- Results and reporting: calculation of gas transmission rate (volume per area per time per unit partial-pressure difference) and gas permeability coefficient (normalized for specimen thickness), plus required test report elements.
Applications and users
ISO 7229:2022 is essential for:
- Manufacturers and suppliers of rubber- or plastics-coated fabrics performing in-house quality control.
- Independent testing laboratories certifying materials for boats, balloons, hoses, gas containers, seals and diaphragms where gas-tightness is critical.
- Product designers and materials engineers selecting coatings based on quantified permeability for safety, durability, and regulatory compliance.
- Procurement and certification bodies requiring standardized permeability data for specifications and contracts.
Practical benefits include consistent material selection, reproducible leak-rate data, improved product safety and lifetime estimates, and compliance with contractual or regulatory permeability requirements.
Related standards
- ISO 2231 - Standard atmospheres for conditioning and testing (referenced for conditioning and lab atmosphere).
- ISO 2286-3 - Determination of roll characteristics - Method for determination of thickness (used for thickness measurement).
