ISO 19723-1:2018 PDF

Road vehicles — Liquefied natural gas (LNG) fuel systems — Part 1: Safety requirements

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Title (English):

ISO 19723-1:2018

Road vehicles — Liquefied natural gas (LNG) fuel systems — Part 1: Safety requirements

Document status:: Withdrawn
Format:: Electronic (PDF)
Number of pages:: 13
Publication date:: July 17, 2018
Edition:: ISO IS 19723 edition 1 version 1
ICS:: 43.060.40

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Description (English):

This document specifies the minimum safety requirements applicable to liquefied natural gas (LNG) on-board fuel system intended for use on the types of motor vehicles defined in ISO 3833. This document is applicable to vehicles (mono-fuel, bi-fuel or dual-fuel applications) using liquefied natural gas in accordance with the ISO 15403 series. It is not applicable to original-production and converted vehicles. All matters relating to the skills of installers and converters have been excluded from this document. This document is only applicable on the components in the "LNG system" meaning an assembly of components (tanks, valves, flexible fuel lines, etc., see Annex B) and connecting parts (fuel lines, fittings, etc.) fitted on motor vehicles using LNG in their propulsion system and related components up to and including the vaporizer. Other parts downstream from the vaporizer are considered as CNG components covered by ISO 15501.

Technical details

Technical committee: ISO/TC 22/SC 41 - Specific aspects for gaseous fuels
SKU: ISO 19723-1:2018

Abstract

Overview

ISO 19723-1:2018 - Road vehicles - Liquefied natural gas (LNG) fuel systems - Part 1: Safety requirements - specifies minimum safety requirements for LNG on-board fuel systems fitted to motor vehicles defined in ISO 3833. The standard covers systems used in mono‑fuel, bi‑fuel and dual‑fuel applications that use LNG in accordance with the ISO 15403 series. It applies to the LNG system components up to and including the vaporizer and excludes downstream CNG components (covered by ISO 15501). The document also excludes matters relating to installer/converter skills and - as stated in the scope - is not applicable to original‑production and converted vehicles.

Key topics and technical requirements

Scope of coverage: Components in the LNG system (tanks, valves, flexible fuel lines, fittings, vaporizer, etc.) and connecting parts fitted on motor vehicles.
Design requirements:
- Components must withstand operational and environmental temperatures (LNG ≈ −162 °C at atmospheric pressure).
- Location, mounting and protection against impact, corrosion, road debris, heat and chemical splash.
- Minimize galvanic corrosion and ensure proper electrical conductivity and grounding to avoid electrostatic charge.
Component-specific rules:
- Tanks and pressure systems designed per service pressure and ISO 12614 series.
- Pressure relief valves (PRV): primary PRV must vent via a pipe‑away to a high level; secondary PRV outlets must be protected and not share the same pipe‑away.
- Excess flow limiting devices: allowed inside or directly on the tank and may be integrated with LNG/CNG automatic valves.
- Automatic valves: must be normally closed when deactivated and only open when LNG operation is selected and the engine is cranking or running.
- Refuelling receptacle: must comply with ISO 12617, include a cap and nearby marking (fuel type and service pressure).
Safety systems: venting system, gas‑tight housings or natural gas detectors for certain vehicle categories, isolation valves, check valves, and provisions up to the vaporizer.
Documentation and marking: instructions for use and component marking requirements.

Practical applications - who uses this standard

Vehicle manufacturers (OEMs) designing LNG‑powered vehicles (M and N categories per ISO 3833).
Component and system suppliers (tanks, PRVs, receptacles, valves, vaporizers).
System integrators and safety engineers for vehicle-level safety design and routing of LNG lines.
Test laboratories and certification bodies conducting compliance and type‑approval testing.
Fleet operators and specifiers seeking safe LNG vehicle procurement and maintenance guidance.

Related standards

ISO 12614 (LNG fuel system components)
ISO 12617 (LNG refuelling connector)
ISO 12991 (LNG on‑board tanks)
ISO 19723‑2 (refuelling connector test methods)
ISO 15500 (CNG fuel system components)
Relevant IEC standards for explosive atmospheres (e.g., IEC 60079 series)

ISO 19723-1:2018 is essential reading for anyone responsible for the safe design, manufacture or certification of on‑board LNG fuel systems for road vehicles.

Related standards

Standards mentioned in the description

Abstract

Overview

Key topics and technical requirements

Scope of coverage: Components in the LNG system (tanks, valves, flexible fuel lines, fittings, vaporizer, etc.) and connecting parts fitted on motor vehicles.
Design requirements:
- Components must withstand operational and environmental temperatures (LNG ≈ −162 °C at atmospheric pressure).
- Location, mounting and protection against impact, corrosion, road debris, heat and chemical splash.
- Minimize galvanic corrosion and ensure proper electrical conductivity and grounding to avoid electrostatic charge.
Component-specific rules:
- Tanks and pressure systems designed per service pressure and ISO 12614 series.
- Pressure relief valves (PRV): primary PRV must vent via a pipe‑away to a high level; secondary PRV outlets must be protected and not share the same pipe‑away.
- Excess flow limiting devices: allowed inside or directly on the tank and may be integrated with LNG/CNG automatic valves.
- Automatic valves: must be normally closed when deactivated and only open when LNG operation is selected and the engine is cranking or running.
- Refuelling receptacle: must comply with ISO 12617, include a cap and nearby marking (fuel type and service pressure).
Safety systems: venting system, gas‑tight housings or natural gas detectors for certain vehicle categories, isolation valves, check valves, and provisions up to the vaporizer.
Documentation and marking: instructions for use and component marking requirements.

Practical applications - who uses this standard

Vehicle manufacturers (OEMs) designing LNG‑powered vehicles (M and N categories per ISO 3833).
Component and system suppliers (tanks, PRVs, receptacles, valves, vaporizers).
System integrators and safety engineers for vehicle-level safety design and routing of LNG lines.
Test laboratories and certification bodies conducting compliance and type‑approval testing.
Fleet operators and specifiers seeking safe LNG vehicle procurement and maintenance guidance.

Related standards

ISO 12614 (LNG fuel system components)
ISO 12617 (LNG refuelling connector)
ISO 12991 (LNG on‑board tanks)
ISO 19723‑2 (refuelling connector test methods)
ISO 15500 (CNG fuel system components)
Relevant IEC standards for explosive atmospheres (e.g., IEC 60079 series)

ISO 19723-1:2018 is essential reading for anyone responsible for the safe design, manufacture or certification of on‑board LNG fuel systems for road vehicles.

ISO 19723-1:2018 PDF

Technical details

Abstract

Overview

Key topics and technical requirements

Practical applications - who uses this standard

Related standards

Related standards

Abstract

Overview

Key topics and technical requirements

Practical applications - who uses this standard

Related standards

Related standards

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