Aerospace - the uses and importance of Vapour Permeability measurement

Vapour permeability testing of technical textiles is critical for ensuring material performance, safety, and durability across the aerospace industry. This includes testing not just for water vapour but also for gases such as hydrocarbons used in fuels, helium, and hydrogen, which are vital across many aerospace applications .


1. Gasbags in Airships

• Gas Retention Efficiency: Fabrics for gasbags must prevent the leakage of light gases like hydrogen or helium. Vapour permeability testing ensures these materials maintain low permeability, preserving lift and reducing operational costs.
• Hydrocarbon Vapours: If hydrocarbons are used in gas mixtures for specific airship applications, vapour permeability testing is essential to ensure the fabric resists hydrocarbon penetration and prevents contamination of the gas environment.
• Material Choices: High-strength materials such as nylon or polyester with coatings of polyurethane, silicone, or fluoropolymers are tested to verify their gas retention and environmental resistance under varying pressures and temperatures.
• Durability in Harsh Conditions: Testing ensures that gasbag fabrics remain impermeable and stable despite exposure to UV radiation, temperature fluctuations, or chemical reactions with stored gases.

2. Fuel Storage and Containment Systems

• Hydrocarbon Resistance: In aerospace fuel tanks or containment systems, liners or barriers. Vapour permeability testing determines their ability to resist hydrocarbons, preventing fuel leakage and ensurre safety.
• Prevention of Vapour Loss: Testing ensures that vapour loss is minimized, improving fuel efficiency and reducing environmental impact.
• Compatibility with Fuels: Vapour permeability testing is conducted for specific hydrocarbons like aviation fuel, kerosene, and JP-8 to ensure textiles can withstand prolonged exposure without degradation.

3. Spacecraft and High-Altitude Applications

• Extreme Environment Adaptability: In spacecraft and high-altitude platforms, textiles must perform under low-pressure conditions where vapours behave differently. Testing ensures materials maintain their properties under these unique conditions.
• Outgassing Control: Vapour permeability testing for hydrocarbons and other gases ensures materials resist outgassing, which can interfere with on-board systems or contaminate delicate instruments.

4. Seals, Gaskets, and Enclosures

• Vapour Containment: Textiles in seals and gaskets for pressurized systems are tested for permeability to ensure minimal vapour transmission, particularly for hydrocarbons or critical gases like hydrogen and helium.
• Long-Term Performance: Testing ensures materials can withstand repeated exposure to specific gases without degradation or loss of sealing properties.

5. Environmental Barriers and Coatings

• Multi-Gas Resistance: Vapour permeability testing extends beyond water vapour to include hydrocarbons and other gases. This is critical for materials exposed to mixed environments, such as fuel systems or high-pressure gas enclosures.
• UV and Chemical Stability: Testing ensures materials resist vapour penetration while withstanding environmental factors like UV radiation and chemical exposure.

6. Thermal Insulation and Structural Materials

• Hydrocarbon Barrier Layers: Technical textiles used in insulation or composite structures near fuel systems are tested to ensure they block hydrocarbon vapours while remaining lightweight and durable.
• Condensation Prevention: Testing for water vapour permeability ensures that insulation materials remain dry, preventing degradation of thermal efficiency or corrosion of adjacent components.

7. Research and Development

• Material Innovation: Testing for multiple gases, including hydrocarbons, allows manufacturers to develop specialized textiles for aerospace needs, such as ultra-lightweight, impermeable fabrics for advanced applications.
• Custom Testing Scenarios: Vapour permeability testing simulates real-world aerospace conditions, ensuring materials meet exacting performance standards before deployment.

Importance of Testing for Multiple Gases, Including Hydrocarbons

1. Safety and Compliance: Materials used in aerospace systems must prevent the escape or penetration of hydrocarbons, which are highly flammable and pose a significant risk.
2. Material Longevity: Prolonged exposure to hydrocarbons can degrade some textiles. Testing ensures materials remain durable and functional over time.
3. Efficiency and Cost-Effectiveness: Minimizing vapour loss, particularly of valuable gases like helium or hydrocarbons in fuel, reduces operational costs and environmental impact.
4. Broad Applicability: Testing for multiple gases ensures materials can perform across a wide range of aerospace systems, from fuel storage to cabin interiors and gasbags.

Conclusion
Vapour permeability testing is indispensable for technical textiles in the aerospace industry. Its application extends from gasbags in airships, where retaining helium and hydrogen is critical, to fuel systems that require resistance to hydrocarbons. Testing for multiple gases ensures materials meet stringent performance, safety, and environmental requirements, driving innovation and reliability in aerospace materials.