Overview
ISO 2435:1973 - "Nitrogen for use in aircraft" defines the required characteristics and supply pressure of gaseous nitrogen used for servicing aircraft systems. This international standard applies to nitrogen compressed in oil-lubricated equipment and is not intended for nitrogen used in aircraft oxygen systems. Use this standard to ensure safe, compatible, and contaminant-controlled nitrogen supply for high‑pressure aircraft applications.
Key topics and technical requirements
The standard sets clear, practical limits on gas quality and supply capability:
- Supply pressure: Must enable charging of aircraft systems up to 343 bar (4 975 lbf/in²) at 20 °C. (Typical working pressures cited: 207, 276, and 343 bar.)
- Purity: Minimum 98.5% by volume nitrogen.
- Oil vapour and particulate contamination: Maximum 0.005 mg total (oil vapour + particulate matter) per cubic decimetre (litre) of nitrogen at 15 °C and 1013 mbar.
- Water content: Not to exceed 0.02 mg per cubic decimetre (litre) at 15 °C and 1013 mbar.
- Particulate size: Any particulate matter must be able to pass through a 10 µm nominal filter.
These requirements focus on contamination control (oil, particulates, moisture) and adequate charging pressure for hydraulic, pneumatic, and other pressurized aircraft systems.
Applications
ISO 2435 is used wherever clean, high‑pressure nitrogen is required for aircraft maintenance and ground support:
- Filling and charging aircraft pneumatic and hydraulic systems
- Pre-flight servicing of landing gear, actuators, and emergency systems that use nitrogen
- Specification input for ground support equipment (GSE) and nitrogen supply stations
- Procurement and quality verification by airlines, MROs (maintenance, repair, overhaul), and ground handling providers
Who should use this standard
- Aircraft maintenance engineers and technicians
- Ground support equipment manufacturers and service providers
- Industrial gas suppliers and cylinder refill stations supplying aviation nitrogen
- Aviation safety and quality assurance teams specifying acceptance criteria
Related standards
ISO 2435 addresses aircraft nitrogen only; nitrogen for oxygen systems and other respiratory/gas-specific standards are handled separately. For integrated procurement and compliance, consult applicable standards for compressed gases, breathing/oxygen systems, and GSE safety in your jurisdiction.
Keywords: ISO 2435, nitrogen for aircraft, aircraft nitrogen standard, nitrogen purity, aircraft charging pressure, nitrogen contamination limits, ground support equipment.