Overview
ISO 3996:1995 specifies test procedures, performance requirements and marking for hydraulic brake hose assemblies used in road-vehicle hydraulic braking systems that employ non-petroleum-base brake fluids (in accordance with ISO 4925). It applies to assemblies with nominal inside hose diameters of 3.2 mm or 4.8 mm, where the hose is fabricated from reinforcing cord and synthetic elastomers and permanently fitted with metal end fittings.
Key topics and technical requirements
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Scope and construction
- Applies to cord-reinforced synthetic-elastomer hoses with metal end fittings.
- Hose construction typically includes an elastomeric lining, two or more cord plies, optional cushion liner and a black weather-resistant outer cover.
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Test programme and sample requirements
- Complete qualification test schedule includes hydrostatic pressure, constriction, volumetric expansion, burst strength, brake-fluid compatibility, whip, tensile, hot impulse, ozone resistance (dynamic), cold bend, salt spray and water absorption tests.
- Typical total sample quantity for a full test cycle: 36 assemblies.
- Test specimens must be new, at least 24 h old and conditioned (last 4 h at 15–32 °C).
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Representative test methods
- Hydrostatic pressure test: using inert gas, air, water or brake fluid (specified pressure ranges for media are given).
- Constriction and expansion tests: measure bore restriction and volumetric expansion under specified pressures with calibrated apparatus.
- Burst strength test: assemblies are pressure-held and then loaded to failure; the standard specifies pressure-hold and minimum burst values (examples shown in the standard: pressure hold 27.6 MPa and minimum burst values indicated for each nominal diameter).
- Brake fluid compatibility: aging while filled with compatible non-petroleum brake fluid at elevated temperature, followed by leak and burst checks.
- Environmental and durability tests: whip, tensile, water absorption, cold bend, dynamic ozone resistance, hot impulse and salt spray.
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Identification and marking
- Requirements for marking hoses and assemblies so product identity, suitability and traceability are clear.
Applications and users
ISO 3996:1995 is intended for:
- Brake hose manufacturers and suppliers developing and certifying assemblies for non-petroleum-base fluids.
- Automotive OEMs specifying brake hose performance for vehicle systems.
- Test laboratories performing Type approval, quality control and supplier audits.
- Regulatory and conformity assessment bodies assessing hydraulic brake components.
Practical benefits include ensuring compatibility with non-petroleum brake fluids, consistent safety margins for burst and pressure performance, and repeatable environmental durability testing.
Related standards
Keywords: ISO 3996:1995, brake hose assemblies, hydraulic braking systems, non-petroleum brake fluid, ISO 4925, hose testing, burst strength, expansion test, constriction test, automotive hose standards.