This document specifies general information regarding the non-return valve component of liquefied 
petroleum gas fuel, intended for use on the types of motor vehicles as defined in ISO 3833. It provides 
general design principles and specifies requirements for instructions and marking. It also specifies test 
requirements for the non-return valve.
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;
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).st edition 2019-12 Road vehicles — Liquefied petroleum gas (LPG) fuel systems components — Part 12: Non-return valve Véhicules routiers — équipements pour véhicules utilisant le gaz de pétrole liquéfié (GPL) comme combustible — Partie 12: clapet anti-retour Reference number ISO 20766-12:2019(E) ？ ISO 2019 ISO 20766-12:2019(E) COPYRIGHT PROTECTED DOCUMENT ？ ISO 標準截圖