ISO 20766-6:2019

Road vehicles - Liquefied petroleum gas (LPG) fuel systems components - Part 6: Pressure relief valves (PRV)

This document specifies general requirements and definitions of liquefied petroleum gas fuel components, intended for use on the types of motor vehicles as defined in ISO 3833. It also provides general design principles, and specifies requirements for instructions and marking. This document is applicable to vehicles (mono-fuel, bi-fuel or dual-fuel applications) using gaseous fuels in accordance with ISO 9162. It is not applicable to the following: a) fuel containers; b) stationary gas engines; c) container mounting hardware; d) electronic fuel management; and e) refuelling receptacles. NOTE 1 It is recognized that miscellaneous components not specifically addressed herein can be examined for compliance with the criteria of any applicable part of ISO 20766, including testing to the appropriate functional tests. NOTE 2 All references to pressure in this document are considered gauge pressures unless otherwise specified. NOTE 3 This document applies to devices which have a service pressure in the range of 110 kPa (Butane rich at 20 °C) and 840 kPa (Propane at 20 °C), hereinafter referred to in this document. Other service pressures can be accommodated by adjusting the pressure by the appropriate factor (ratio).

Véhicules routiers — Équipements pour véhicules utilisant le gaz de pétrole liquéfié (GPL) comme combustible — Partie 6: Vannes de contrôle de la surpression

General Information

• Status: Published
• Publication Date: 12-May-2019
• ICS: 43.060.40 - Fuel systems
• Technical Committee: ISO/TC 22/SC 41 - Specific aspects for gaseous fuels
• Drafting Committee: ISO/TC 22/SC 41/WG 6 - Fuel system components and refuelling connector for vehicles propelled by Liquefied Petroleum Gas (LPG)
• Current Stage: 9060 - Close of review
• Completion Date: 02-Dec-2029

Relations

• Amended By: ISO 20766-6:2019/Amd 1:2022 - Road vehicles - Liquefied petroleum gas (LPG) fuel systems components - Part 6: Pressure relief valves (PRV) - Amendment 1
• Effective Date: 13-Oct-2020

Overview

ISO 20766-6:2019 specifies requirements for pressure relief valves (PRV) used in LPG fuel systems for road vehicles. It is part of the ISO 20766 series covering LPG fuel system components and focuses on definitions, design principles, marking, construction and testing to ensure safe, reliable venting of overpressure in vehicle LPG systems. The standard applies to mono‑fuel, bi‑fuel and dual‑fuel vehicles (as defined in ISO 3833) using gaseous fuels per ISO 9162, and addresses devices with service pressures from 110 kPa to 840 kPa (gauge pressure).

Key topics and technical requirements

• Scope and exclusions
  • Applicable to LPG PRVs for vehicle use; not applicable to fuel containers, stationary gas engines, container mounting hardware, electronic fuel management, or refuelling receptacles.
• Marking
  • Components must be marked to allow traceability: manufacturer/agent, model/part number, and working pressure (and recommended additional markings such as flow direction, fuel type, certification symbol).
• Construction and assembly
  • PRVs should be mounted in the vapour phase and designed with a discharge pressure ≤ 1.0 × working pressure (WP).
• Testing and performance
  • PRVs must meet the applicable provisions of ISO 20766‑1 and ISO 20766‑2 and pass specific tests in Clause 6, including:
    • Hydrostatic strength: tested at 2.25 × WP to verify body strength (moving parts may be blocked).
    • Leakage: evaluated at specified temperatures and fractions of WP.
    • Continued operation: capable of 600 cycle operations (open/vent and re‑seat cycles within 10 s ± 2 s), followed by leakage test.
    • Operational test: opening and re‑seating pressures verified on samples; opening pressure within ±5% of manufacturer’s set pressure; re‑seating ≥ 90% of set pressure and within ±5% of average; temperature tests require minimum percentages of reference values (e.g., opening ≥ 85% at temperature extremes).
    • Additional tests: corrosion, vibration, material compatibility, temperature cycling, etc.
• Production quality
  • Manufacturers must implement a production batch inspection and acceptance testing program to ensure consistent safety performance.

Applications and who uses it

• Target users:
  • PRV and LPG component manufacturers
  • Vehicle OEMs integrating LPG systems
  • Test laboratories and conformity assessment bodies
  • Regulatory authorities, safety engineers, and aftermarket component suppliers
• Practical uses:
  • Designing, certifying and validating PRVs for automotive LPG systems, ensuring compliance with international safety and performance expectations.

Related standards

• ISO 20766‑1: General requirements and definitions
• ISO 20766‑2: Performance and general test methods
• ISO 9162: Gaseous fuel characteristics and requirements
• ISO 3833: Vehicle type definitions

Keywords: ISO 20766-6, pressure relief valve, PRV, LPG fuel systems, road vehicles, hydrostatic strength, operational test, LPG safety, production inspection.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 20766-6
First edition
2019-05
Road vehicles — Liquefied petroleum
gas (LPG) fuel systems components —
Part 6:
Pressure relief valves (PRV)
Véhicules routiers — Équipements pour véhicules utilisant le gaz de
pétrole liquéfié (GPL) comme combustible —
Partie 6: Vannes de contrôle de la surpression
Reference number
©
ISO 2019
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
ii © ISO 2019 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Markings . 2
5 Construction and assembly . 2
6 Tests . 2
6.1 Applicability . 2
6.2 Hydrostatic strength . 3
6.3 Leakage . 3
6.4 Continued operation . 3
6.5 Operational test . 4
6.5.1 General. 4
6.5.2 Test procedure . 4
7 Production batch inspection and acceptance testing . 4
Foreword
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This document was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 41,
Specific aspects for gaseous fuels.
A list of all parts in the ISO 20766 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
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iv © ISO 2019 – All rights reserved

INTERNATIONAL STANDARD ISO 20766-6:2019(E)
Road vehicles — Liquefied petroleum gas (LPG) fuel
systems components —
Part 6:
Pressure relief valves (PRV)
1 Scope
This document specifies general requirements and definitions of liquefied petroleum gas fuel
components, intended for use on the types of motor vehicles as defined in ISO 3833.
...