ISO 20766-21:2023

Overview

ISO 20766-21:2023 specifies general requirements for pressure and/or temperature sensors used in liquefied petroleum gas (LPG) fuel systems for road vehicles as defined in ISO 3833. The standard focuses on component-level design principles, identification and marking, and applicable tests to verify mechanical and environmental performance. It applies to mono-fuel, bi-fuel and dual-fuel vehicle applications that use gaseous fuels in accordance with ISO 9162, and addresses devices with service pressures between 110 kPa and 840 kPa (gauge pressures unless otherwise specified).

Key Topics

• Scope and applicability

  • Sensors intended for mobile road vehicles (not fuel containers, stationary engines, container mounting hardware, electronic fuel management or refuelling receptacles).
  • Recognizes that other components may be assessed using applicable parts of the ISO 20766 series.

• Marking and identification

  • Sensors shall carry clear, indelible markings including: manufacturer or agent name/trademark, model/part number, working pressure and temperature range, and year/month of fabrication.
  • Recommended additional markings: flow direction, fuel type, electrical ratings, certification symbol, type approval number, serial/date code and a reference to ISO 20766-21.

• Construction and assembly

  • Devices must withstand the maximum operating pressure and the specified operating temperature range.
  • Electrically operated sensors require insulation and isolation to prevent current conduction through LPG-containing parts; isolation resistance shall exceed 10 MΩ.
  • Materials in contact with the heat exchange medium must be compatible with LPG and able to withstand specific test pressures (e.g., 200 kPa for heat exchange fluid compatibility where applicable).

• Testing requirements (see ISO 20766-2 for procedures)

  • Hydrostatic strength: test pressure = 2.25 × working pressure.
  • External leakage, high temperature and low temperature leakage tests: leakage limits and conditioning periods defined; components must not exceed specified leak rates when tested at 150% of working pressure and designated temperatures.
  • Additional tests (corrosion, immersion, creep, ozone ageing, temperature cycling) apply as relevant and are indicated in the standard's test matrix.

Applications

• Use in LPG fuel systems for passenger cars, commercial vehicles and other mobile road vehicles using LPG as a fuel source.
• Integration into mono-, bi- or dual-fuel vehicle platforms to monitor pressure and/or temperature for safety, control and diagnostics.
• Helps manufacturers and suppliers demonstrate conformity to a recognized international benchmark for sensor design, marking and performance testing.

Related Standards

• ISO 20766-1 - General requirements and definitions for LPG fuel system components.
• ISO 20766-2 - Performance and general test methods referenced for hydrostatic, leakage and temperature tests.
• ISO 3833 - Vehicle types and definitions (referenced for vehicle applicability).
• ISO 9162 - Specifications for LPG fuels (class F).

ISO 20766-21:2023 provides a clear framework for designing, marking and testing LPG pressure and temperature sensors so manufacturers, system integrators and certification bodies can ensure safety, compatibility and regulatory compliance in automotive LPG applications.