ISO 20766-5:2023

Overview

ISO 20766-5:2023 provides definitions and general requirements for liquefied petroleum gas (LPG) fuel selection systems and electrical installations 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. It specifies design principles, marking and instructions, and identifies mandatory tests and performance criteria for safe, reliable operation within the service pressure range of 110 kPa to 840 kPa.

Key exclusions include fuel containers, stationary gas engines, container mounting hardware and refuelling receptacles.

Key Topics

• Scope and applicability: Components intended for vehicle use (mono/bi/dual‑fuel) and the pressure range covered. Other service pressures can be accommodated by adjusting the pressure by the appropriate factor.
• Marking requirements: Components must allow traceability by marking manufacturer name/trademark, model/part number and operating specifications (temperature range, electrical rating). Recommended markings include fuel type, certification symbol, approval numbers and a reference to ISO 20766-5.
• Construction and assembly:
  • Systems must withstand maximum operating pressure and the specified temperature range.
  • Electrically operated fuel selection systems shall plug into the harness using the same connector or an adapter.
  • Electrical insulation must prevent current flow through LPG-containing parts; isolation resistance shall exceed 10 MΩ.
  • Wiring and connectors must be suitable for automotive use, protected from abrasion, flexing and heat, and secured at intervals not exceeding 40 cm.
  • Overload protection: at least one dedicated fuse sized for the system with location documented in the operator manual.
• Electrical connection quality: Sealed connectors with positive locking, manufacturer‑recommended connectors, or soldered connections protected by heavy wall shrink insulation are required. The use of electrical tape for bare connections is not permitted.

Tests

ISO 20766-5 references required tests and criteria, many of which are performed per ISO 20766-2. Notable tests and acceptance criteria included in the document:

• Continued operation: 50 000 switching operations at room temperature with cycles apportioned 80% ambient, 10% at -40 °C and 10% at 85 °C; successful completion requires passing the insulation resistance test.
• Vibration resistance: Components with moving parts or printed circuit boards must remain undamaged and operational while powered during vibration tests.
• Temperature cycle: 96‑hour cycles between minimum and maximum operating temperatures with 120 min cycle time; component must be in working condition and meet insulation criteria afterward.
• Insulation resistance: Apply 500 V d.c. for 60 s; minimum allowable resistance 240 kΩ.
• Minimum operating voltage: ≤ 8 V for 12 V systems and ≤ 16 V for 24 V systems while in working condition.

Applications

ISO 20766-5:2023 is directly applicable to:

• Automotive OEM and aftermarket components for LPG fuel selection and associated electrical installations.
• Design verification and type approval testing of LPG switching devices, wiring harness interfaces and electrical modules used in mono/bi/dual‑fuel vehicles.
• Installation guidance for vehicle converters, system integrators and certification bodies evaluating component compliance.

Related Standards

• ISO 20766 series (all parts), including ISO 20766-1:2018 (general requirements) and ISO 20766-2:2018 (performance and test methods)
• ISO 3833 (vehicle types and definitions)
• ISO 9162 (gaseous fuel requirements)
• Relevant material and fuel standards referenced in the ISO 20766-5 bibliography (for example ISO 11114-2)

Compliance with ISO 20766-5:2023 helps ensure safe electrical integration, robust switching performance and traceable marking for LPG fuel systems used in road vehicles.