SIST EN 2104:2001

Overview

EN 2104:1996 is a CEN aerospace series standard that specifies the required properties of acrylonitrile-butadiene rubber (NBR) with a nominal hardness of 40 IRHD for aerospace applications. The document defines the material designation and the property requirements that NBR compounds must meet when used in aircraft and space systems. EN 2104:1996 has been adopted nationally in some countries (for example as SIST EN 2104:2001 in Slovenia).

Key topics and requirements

The standard focuses on the characterization and control of NBR materials intended for aerospace use. Main topics include:

• Hardness specification (40 IRHD) - the standard identifies the target hardness class and references the IRHD measurement method for rubber.
• Material identification and designation - clear definition of the NBR grade for procurement and certification.
• Performance attributes - sets out the required physical and performance characteristics that are relevant to aerospace components (e.g., resistance and behavior under operational conditions).
• Testing and conformity - references test methods and inspection criteria required to demonstrate that supplied materials meet the standard’s requirements.
• Documentation and marking - guidance on material traceability, certificates of conformity and supplier documentation to support aerospace quality systems.
• Application limitations - notes on intended use in aerospace environments so designers and specifiers understand suitability constraints.

(EN 2104:1996 emphasizes the properties and acceptance criteria rather than prescribing manufacturing recipes or proprietary formulations.)

Applications

EN 2104:1996 is intended for organizations specifying, procuring or manufacturing rubber parts for aircraft and space systems where a 40 IRHD NBR compound is required. Typical practical applications include:

• Seals and gaskets for hydraulic, fuel and pneumatic systems
• O-rings and static/dynamic sealing elements
• Flexible couplings, hoses and vibration-damping components
• Any rubber component in which oil/chemical resistance and controlled hardness are critical

Using the standard helps ensure consistent material performance and interchangeability across suppliers and maintenance operations.

Who uses this standard

• Aerospace designers and materials engineers specifying elastomeric components
• Procurement and quality managers in aerospace supply chains
• Rubber compounders and component manufacturers supplying aerospace OEMs
• Testing laboratories and conformity assessment bodies
• Maintenance, repair and overhaul (MRO) organizations ensuring replacement parts meet original material criteria

Related standards (typical)

• Other CEN/EN aerospace material standards for elastomers and sealing materials
• National adoptions (for example SIST EN 2104:2001) and industry-specific test-method standards referenced by EN 2104

Keywords: EN 2104:1996, NBR 40 IRHD, acrylonitrile-butadiene rubber, aerospace rubber standard, CEN, aerospace seals and gaskets, rubber material specification.