Overview
ISO 8789:2020 specifies requirements for rubber hoses and hose assemblies for liquefied petroleum gas (LPG) in motor vehicles. Applicable to hoses up to a maximum size of 19, the standard covers construction, materials, dimensions, physical properties and performance testing for LPG (propane) service. It is the 2020 (fourth) edition and harmonizes international requirements for vehicle LPG systems (for example, United Nations Regulation No. 67).
Key facts:
- Maximum working pressure: 3.0 MPa (30 bar)
- Operating temperature range: −40 °C to +80 °C
- Maximum hose size: 19
Key topics and technical requirements
ISO 8789:2020 defines both material and performance criteria, including:
- Materials & construction: smooth-bore LPG-resistant rubber liner, reinforcement (textile or corrosion-resistant wire), and oil/weather-resistant rubber cover (cover omitted if wire-reinforced). Covers must be pin‑pricked to reduce gas‑permeation bubble formation.
- Dimensions & tolerances: inside diameter and minimum bending radii for each hose size; concentricity requirements (≤ 1.0 mm).
- Physical properties of compounds: minimum tensile strength (≥ 10 MPa) and elongation at break (≥ 250%) for lining and cover, plus resistance to ageing and solvent (n‑pentane) effects.
- Performance tests: proof pressure (7.5 MPa / 75 bar hold), minimum burst pressure (15.0 MPa / 150 bar), adhesion, low‑temperature flexibility (−40 °C), ozone resistance and permeability to propane (tested per ISO 4080).
- Fittings: stainless steel, brass or plated ferrous materials; crimp‑on or reusable screw‑together types. Swivel nuts use UNF or metric threads and sealing is preferably by a 45° flare.
- Hose assembly tests: underwater leakage at 3.0 MPa, burst/proof tests and permeability checks; marking and test frequency requirements are specified.
Applications and users
ISO 8789:2020 is essential for:
- Hose and hose‑assembly manufacturers designing and producing LPG fuel lines for vehicles
- Automotive OEMs specifying supplier components for factory‑fitted LPG systems
- Aftermarket suppliers and installers of LPG conversions and repair kits
- Test laboratories and certification bodies performing type and production tests in accordance with international regulations
- Regulatory authorities and compliance engineers referencing harmonized safety criteria (e.g., UN R67)
Related standards
Normative references include ISO test methods and related standards such as:
ISO 8789:2020 helps ensure safety, durability and regulatory compliance for LPG fuel lines in motor vehicles by specifying materials, dimensions and rigorous performance testing.