Overview
ISO 4930:2006 - Road vehicles: Elastomeric seals for hydraulic disc brake cylinders (service temperature 150 °C max.) specifies performance test methods and requirements for elastomeric seals used in road‑vehicle disc brake cylinders that operate with a non‑petroleum base hydraulic brake fluid. The standard applies to solid‑section seals (square, rectangular, O‑ring) mounted either in the cylinder bore or on the movable piston. Key objectives are to verify fluid compatibility, thermal stability, leakage performance and durability up to a maximum service temperature of +150 °C and down to −40 °C.
Key topics and technical requirements
- Scope and product requirements
- Applicable to solid‑section elastomeric seals for disc brake cylinders; seals must be free of visible defects and suitable for −40 °C to +150 °C operation.
- Test fluids and apparatus
- Test fluid per ISO 4926 (compatibility fluid); specific apparatus includes ovens, test jars, high‑ and low‑temperature stroking fixtures and cold chambers.
- Performance tests covered
- Resistance to fluid at elevated temperature (physical stability and precipitation characteristics)
- Resistance to elevated temperature in dry air (heat ageing)
- Ambient‑temperature stroking test (dynamic leakage)
- High‑temperature stroking test (dynamic performance at elevated temperature)
- Low‑temperature leakage test (static/dynamic sealing at −40 °C)
- Cycling humidity storage corrosion test (assembly corrosion and adhesion)
- Acceptance criteria (examples from the standard)
- Volume change after fluid exposure: 0% to +15%
- Hardness change after fluid exposure: 0 IRHD to −15 IRHD
- Precipitation (sediment) in fluid: ≤ 0.3% by volume
- No leakage beyond normal wetting during stroking tests; seals must remain flexible and return to shape after low‑temperature testing.
Applications and who uses ISO 4930:2006
- Automotive OEMs and brake system designers use the standard to specify acceptable seal materials and designs for hydraulic disc brakes using non‑petroleum fluids.
- Elastomer and component suppliers rely on ISO 4930 for material qualification, batch acceptance and product development.
- Test laboratories and QA engineers perform the specified thermal, chemical and leakage tests to validate compliance.
- Procurement and certification bodies include ISO 4930 requirements in supplier contracts and product certification schemes to ensure system safety and reliability.
Related standards
- ISO 4926 - Non‑petroleum base reference fluids (brake test fluids)
- ISO 4928 - Elastomeric cups and seals for hydraulic braking systems (service temperature 120 °C max.)
- ISO 48 - Rubber hardness (IRHD)
- ISO 188 - Accelerated ageing and heat resistance tests
- ISO 1817 - Effect of liquids on vulcanized rubber
Keywords: ISO 4930:2006, elastomeric seals, hydraulic disc brake cylinders, non‑petroleum brake fluid, seal testing, high‑temperature stroking test, low‑temperature leakage, brake seal standards.