ISO 20766-4:2018

Overview

ISO 20766-4:2018 - "Road vehicles - Liquefied petroleum gas (LPG) fuel system components - Part 4: Level indicator" specifies requirements, definitions and tests for LPG level indicators used on road vehicles (mono‑fuel, bi‑fuel or dual‑fuel) as defined in ISO 3833. The standard covers general design principles, marking and instructions, and functional and safety tests for devices operating in the LPG service pressure range of 110 kPa to 840 kPa (adjustable by ratio for other pressures). It excludes fuel containers, stationary gas engines, container mounting hardware, electronic fuel management and refuelling receptacles.

Key topics and requirements

• Scope and definitions: Applies to LPG level indicators for motor vehicles using gaseous fuels per ISO 9162. Pressure references are gauge pressures unless stated otherwise.
• Marking and traceability: Components must be marked with manufacturer/agent identification, model/part number and working pressure (or pressure and temperature range). Recommended markings include flow direction, fuel type, electrical ratings, certification symbol, type approval number and serial/date code.
• Construction and electrical protection: Level indicator construction must comply with ISO 20766-1/2; electrical connections shall meet IP54 (IEC 60529).
• Functional and durability tests:
  • Hydrostatic strength: tested at 2.25 × working pressure (WP).
  • Leakage: specified test temperatures and pressure factors (e.g., −40/−20 °C at 0.75×WP and 0.025×WP; 20 °C at 0.025×WP and 2.25×WP; 85 °C at 0.05×WP).
  • Continued operation: 6 000 cycles between empty and 80% tank valve cut‑off; readings must remain within declared tolerance and component must pass hydrostatic retest.
  • Insulation resistance for electrical variants: apply DC 1 000 V between connector pin and housing for ≥2 s; minimum allowable resistance 240 kΩ.
  • Float pressure test: floats must withstand 3 000 kPa external pressure.
• Other applicable tests: leakage, excess torque resistance, bending moment, corrosion, vibration, temperature cycling and material compatibility as referenced in ISO 20766-2.

Applications and users

Who uses ISO 20766-4:2018:

• LPG component manufacturers and designers - for product design, marking and test requirements.
• Automotive OEMs and system integrators - to select compliant level indicators for LPG vehicles.
• Test laboratories and certification bodies - to perform required hydrostatic, leakage, electrical and durability tests.
• Regulators, procurement teams and aftermarket suppliers - to verify safety, traceability and type‑approval for vehicle LPG fuel systems.

Practical uses include product development, type‑approval testing, compliance documentation, procurement specifications and installation/maintenance guidance for LPG vehicle fuel systems.

Related standards

• ISO 20766 series (Parts 1 and 2 referenced)
• ISO 3833 (vehicle categories)
• ISO 9162 (gaseous fuels)
• IEC 60529 (IP Code)
• EN 12806, EN 589 (see bibliography for additional references)