ISO 20766-25:2022

Overview

ISO 20766-25:2022 - "Road vehicles - Liquefied petroleum gas (LPG) fuel system components - Part 25: Gas connections" defines general requirements, definitions, design principles, marking and testing requirements for LPG gas connections used on road vehicles (as defined in ISO 3833). The standard applies to mono‑fuel, bi‑fuel and dual‑fuel vehicle applications using gaseous fuels in accordance with ISO 9162 and covers components with service pressures in the range 110 kPa to 840 kPa (gauge pressures). It excludes fuel containers, refuelling receptacles, stationary gas engines, container mounting hardware and electronic fuel management.

Key Topics and Requirements

• Scope & Definitions: Applies to vehicle gas connections within the ISO 20766 series; pressure references are gauge pressure unless stated otherwise. Other service pressures may be accommodated by pressure-ratio adjustment.
• Marking: Components must be traceable and marked with manufacturer/agent name or trademark, model/part number, working pressure (or pressure/temperature range), serial number/date code and flow direction (if required). Additional recommended markings include fuel type, electrical ratings, certification symbol and a reference to ISO 20766-25.
• Construction and Materials:
  • No soldered or welded joints except for attaching parts of detachable couplings to tubes.
  • Gas tubes must use corrosion‑compatible fittings; distribute blocks must be corrosion‑resistant.
  • Joints and fittings must not damage tubes and must meet equal or higher burst pressure than the tube.
  • Minimize number of joints; locate joints for inspection; avoid gas‑carrying connections in passenger compartments except in specified sealed housings or protected filling unit sleeves.
• Testing Requirements (referenced to ISO 20766-2 procedures):
  • Hydrostatic strength: test pressure = 2.25 × working pressure.
  • Continued operation: endurance test for 100 000 cycles.
  • Pull-off: tensile separation test along tube axis; acceptance force F calculated as: F = (π × d × P) / 10 where d = internal diameter in mm, P = maximum working pressure in MPa (bar).
  • Other applicable tests: leakage, excess torque, bending moment, corrosion, vibration, material compatibility and temperature cycling.

Applications and Users

ISO 20766-25 is intended for:

• Automotive OEMs designing LPG fuel systems and component suppliers producing gas connections.
• Test laboratories and conformity assessment bodies performing ISO 20766 series tests.
• Certification agencies and regulators establishing safety and type-approval criteria for LPG vehicle components.
• System integrators and installers ensuring correct selection, marking and installation of gas connections to prevent leaks and galvanic corrosion.

Practical uses include product design validation, production quality control, component marking/traceability and type‑approval testing for LPG vehicle fuel system safety.

Related Standards

• ISO 20766-1 (General requirements and definitions)
• ISO 20766-2 (Performance and general test methods)
• ISO 3833 (Vehicle types - terms and definitions)
• ISO 9162 (Specifications for liquefied petroleum gases)

Keywords: ISO 20766-25, LPG gas connections, road vehicles, liquefied petroleum gas, LPG fuel system components, hydrostatic strength, pull-off test, continued operation.