ISO 20766-18:2019

Overview

ISO 20766-18:2019 specifies requirements for hoses used in liquefied petroleum gas (LPG) fuel systems for road vehicles (as defined in ISO 3833). It sets out design principles, mandatory marking and instructions, construction rules for rubber and synthetic hoses, coupling and assembly requirements, and detailed test methods (hydrostatic, temperature, tensile, permeability, bending, impulse, gas-tightness). The standard applies to mono-fuel, bi-fuel and dual-fuel vehicle applications using gaseous fuels per ISO 9162 and covers service pressures commonly between 110 kPa and 840 kPa (gauge), with alternative pressures accommodated by linear scaling.

Key topics and technical requirements

• Scope and exclusions: Applicable to vehicle LPG hose components; excludes fuel containers, stationary gas engines, container mounting hardware, electronic fuel management and refuelling receptacles. Fully metal bendable hoses are excluded.
• Marking: Hoses must be indelibly marked at intervals ≤ 0.5 m with manufacturer/trademark, part number, working pressure and temperature range, fabrication year/month, and size/type. Recommended markings include flow direction, fuel type and certification marks.
• Construction:
  • Rubber hoses: smooth-bore tube, synthetic cover, reinforced interlayers; covers to protect reinforcement from corrosion unless reinforcement is corrosion-resistant.
  • Synthetic hoses: thermoplastic tube and cover; similar reinforcement and cover requirements.
  • Couplings: steel or brass, corrosion-resistant surfaces, crimp-fitting type; swivel nuts with UNF thread and 45° sealing cone where applicable. Banjo bolts to comply with DIN 7643.
• Assembly: Design should avoid peeling covers except where reinforcement requires it. If assemblies are provided by separate parties, approval must include hose, coupling, and assembly instructions in local language or English.
• Testing:
  • Hydrostatic strength: test pressure = 2.25 × working pressure.
  • Temperature leakage: leakage ≤ 15 cm³/h (checked at room temperature after conditioning) when tested at minimum (−40 °C or −20 °C) and maximum (65/85/120 °C) operating temperatures at 150% working pressure, after ≥8 h conditioning.
  • Tensile/elongation: rubber lining/cover ≥ 10 MPa and elongation ≥ 250%; synthetic lining/cover generally ≥ 20 MPa and elongation ≥ 200%. Polyamide 6 has additional ISO 527-2 test conditions and conditioning.

Applications and users

• Vehicle OEMs and Tier‑1 suppliers designing LPG fuel systems
• Hose and coupling manufacturers for product specification and type approval
• Test laboratories conducting hydrostatic, permeability, temperature and impulse testing
• Certification bodies / regulators evaluating component compliance and marking
• Conversion garages and fleet operators selecting compliant hoses for LPG conversions and maintenance

Related standards

• ISO 20766-1 (general requirements and definitions)
• ISO 20766-2 (performance and general test methods)
• ISO 3833, ISO 9162, ISO 37, ISO 527-2, ISO 1307, ISO 4080, ISO 1436, DIN 7643

Keywords: ISO 20766-18, LPG hose standard, liquefied petroleum gas fuel systems, hose testing, hydrostatic strength, tensile requirements, vehicle LPG components.