ISO 20766-9:2019

INTERNATIONAL ISO
STANDARD 20766-9
First edition
2019-05
Road vehicles — Liquefied petroleum
gas (LPG) fuel systems components —
Part 9:
Pressure relieve device (PRD)
Véhicules routiers — Équipements pour véhicules utilisant le gaz de
pétrole liquéfié (GPL) comme combustible —
Partie 9: Dispositif de limitation de pression
Reference number
©
ISO 2019
© ISO 2019
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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 Bending moment . 3
6.5 Continued operation . 4
6.5.1 Test procedure . 4
6.5.2 Requirements . 4
6.6 Accelerated life . 4
6.6.1 General. 4
6.6.2 Test procedure . 4
6.6.3 Accelerated-life test temperature. 4
6.6.4 Requirements . 5
6.7 Benchtop activation . 5
6.7.1 General. 5
6.7.2 Thermally-activated relief devices . 5
6.8 Thermal cycling . 5
6.8.1 Test procedure . 5
6.8.2 Requirements . 6
6.9 Condensate-corrosion resistance . 6
6.9.1 Test procedure . 6
6.9.2 Test solution. 6
6.10 Flow capacity . 6
6.10.1 General. 6
6.10.2 Test procedure . 6
7 Production batch inspection and acceptance testing . 7
Annex A (normative) Determination of fusible material yield temperature and PRD
activation temperature . 8
Foreword
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bodies (ISO member bodies). The work of preparing International Standards is normally carried out
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electrotechnical standardization.
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described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
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URL: www .iso .org/iso/foreword .html
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
complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO 2019 – All rights reserved

INTERNATIONAL STANDARD ISO 20766-9:2019(E)
Road vehicles — Liquefied petroleum gas (LPG) fuel
systems components —
Part 9:
Pressure relieve device (PRD)
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. 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).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 20766-1, Road vehicles — Liquefied petroleum gas (LPG) fuel systems components — Part 1: General
requirements and definitions
ISO 20766-2, Road vehicles — Liquefied petroleum gas (LPG) fuel systems components — Part 2:
Performance and general test methods
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 20766-1 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http: //www .electropedia .org/
— ISO Online browsing platform: available at https: //www .iso .org/obp
3.1
activation pressure
rupture pressure
pressure, as specified by the pressure relief device (PRD) m
...