ISO 7229 Rubber or Plastic Coated Fabrics - Measurement of Gas Permeability

The ISO 7229 Rubber or plastic coated fabrics - Measurement of gas permeability standard, published by the International Organization for Standardization (ISO), describes two methods for measuring gas passage, or permeability, through rubber or plastic coated fabrics.

In principle, a test piece is placed between two parts of a hermetically sealed measuring cell. Each part of the cell is vacuumed, then one part is filled with test gas to a specific pressure level. The amount of gas passing from the test piece to the lower-pressure side is measured and determined by a pressure sensor or a gas chromatograph. In the gas chromatography method, the measurement condition obtained by using equal pressure between the two parts of the cell is given in Appendix A for information, as the value obtained by dividing it by the test piece.

The ISO 7229 standard defines standardized test methods for determining the gas permeability (also called gas transmission rate) of rubber or plastic-coated fabrics. This property is critical for materials where control of gas passage is important, such as inflatable structures, protective clothing, inflatable boats, lifeboats, balloons, gas-holding pouches, or technical textiles requiring air or gas impermeability.

This standard specifies two different methods for measuring how easily gases pass through coated fabrics:

• Method A: This is generally a pressure-based or manometric method and is typically used for materials with low permeability.
• Method B: An alternative technique (e.g., involving flow measurement or different equipment setup) offers flexibility depending on the expected permeability level and available equipment.

These methods are particularly important when the expected gas permeability is relatively low (in previous versions, it was explicitly stated that they were valid for permeabilities lower than approximately 3 units under certain conditions, but the exact threshold may vary depending on the version).

Coated fabrics tested according to the ISO 7229 standard are commonly used in products that need to retain air or other gases over time, resist leakage, or provide controlled permeability. Examples include:

• Inflatable life-saving equipment (for example, those referenced in standards such as ISO 12402 for personal swimming devices)
• Protective clothing and shelters
• Flexible storage tanks or balloons
• Technical textiles used in automotive, aerospace, or marine applications.

This standard refers to various supporting ISO documents for conditioning and preparation, such as:

• ISO 2231 Standard atmospheres for conditioning and testing rubber or plastic coated fabrics.
• ISO 2286 series: Determination of the physical properties of coated fabrics (mass per unit area, thickness, etc.)

This standard plays a vital role in quality control and performance verification for manufacturers of high-performance coated textiles, enabling consistent and reliable measurement of gas barrier properties among laboratories and suppliers worldwide.

In short, the main purpose of the ISO 7229 standard is to define how to measure gas transmission through rubber or plastic-coated fabrics; this important property is known as gas permeability. This standard focuses particularly on:

• Defining standardized laboratory methods for evaluating the rate of gas passage through rubber or plastic-coated textile fabrics.
• Providing consistent, repeatable, and comparable data on gas permeability so that manufacturers, testers, and specifiers can accurately evaluate materials.
• In situations where gas tightness is critical (e.g., in outdoor products, hoses, inflatable products, gaskets or technical protective materials), quality assurance, product design, safety assessment and support for contractual or regulatory compliance.

This standard defines two basic methods for measuring gas permeability:

• Pressure sensor method: A test piece is placed in a hermetically sealed chamber, one side is pressurized with test gas, and the pressure increase on the lower-pressure side is monitored by sensitive sensors. This method monitors gas transmission by observing changes in pressure over time.
• Gas chromatography (GC) method: This method analytically measures the amount of gas passing through the test sample using gas chromatography, instead of pressure change. An informative appendix presents an equal-pressure variant of this approach, enabling alternative measurement setups.

The ISO 7229 standard requires conditioned samples, controlled atmospheres, and defined transport areas, and specifies how to calculate and report key results such as gas transmission velocity and gas permeability coefficient. Both are normalized with respect to area, time, and pressure difference.

The ISO 7229 standard is widely used by:

• For in-house quality control by manufacturers of coated fabrics and related products.
• Independent testing laboratories that evaluate material performance for clients or certification bodies.
• Product designers and engineers need reliable permeability data to select suitable materials.
• Procurement, regulatory, or compliance teams that require standardized test results in specifications and contracts.

The ISO 7229 standard provides a uniform test framework, enabling materials compared across different laboratories and suppliers to be evaluated under consistent conditions. This reduces uncertainty, increases product reliability, and supports safety in applications where gas permeability is critical.

For many years, our organization, with its competent and experienced staff, has been understanding the needs of its clients, providing the advanced testing services they require, and assisting in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services to businesses in accordance with the "ISO 7229 Rubber or plastic coated fabrics - Measurement of gas permeability" standard.