kSIST FprEN ISO 16923:2025

SLOVENSKI STANDARD
oSIST prEN ISO 16923:2025
01-februar-2025
Polnilne postaje za oskrbo z zemeljskim plinom - Postaje za oskrbo vozil s
stisnjenim zemeljskim plinom (ISO/DIS 16923:2024)
Natural gas fuelling stations - CNG stations for fuelling vehicles (ISO/DIS 16923:2024)
Gasfüllanlagen - CNG Füllanlagen zur Betankung von Fahrzeugen (ISO/DIS
16923:2024)
Stations-service de gaz naturel - Stations GNC pour le ravitaillement de véhicules
(ISO/DIS 16923:2024)
Ta slovenski standard je istoveten z: prEN ISO 16923
ICS:
75.200 Oprema za skladiščenje Petroleum products and
nafte, naftnih proizvodov in natural gas handling
zemeljskega plina equipment
oSIST prEN ISO 16923:2025 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

oSIST prEN ISO 16923:2025
oSIST prEN ISO 16923:2025
DRAFT
International
Standard
ISO/DIS 16923
ISO/TC 340
Natural gas fuelling stations — CNG
Secretariat: AFNOR
stations for fuelling vehicles
Voting begins on:
Stations-service de gaz naturel — Stations GNC pour le
2024-12-25
ravitaillement de véhicules
Voting terminates on:
ICS: 75.200 2025-03-19
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
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BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
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POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS.
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION.
Reference number
ISO/DIS 16923:2024(en)
oSIST prEN ISO 16923:2025
DRAFT
ISO/DIS 16923:2024(en)
International
Standard
ISO/DIS 16923
ISO/TC 340
Natural gas fuelling stations — CNG
Secretariat: AFNOR
stations for fuelling vehicles
Voting begins on:
Stations-service de gaz naturel — Stations GNC pour le
ravitaillement de véhicules
Voting terminates on:
ICS: 75.200
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2024
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
BE CONSIDERED IN THE LIGHT OF THEIR
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TO SUBMIT, WITH THEIR COMMENTS,
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NOTIFICATION OF ANY RELEVANT PATENT
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Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland Reference number
ISO/DIS 16923:2024(en)
ii
oSIST prEN ISO 16923:2025
ISO/DIS 16923:2024(en)
Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 3
4 Symbols and abbreviated terms. 8
4.1 Symbols .8
4.2 Abbreviated terms .8
5 Risk management . 9
6 Fuel supply to the fuelling station .12
6.1 Supply by pipeline . 12
6.2 Supply by mobile storage . 13
7 Dryer . 14
8 Compressors . 14
8.1 General .14
8.2 Instrumentation and control . 15
8.3 Crankcase design . 15
8.4 Compressor enclosures, buildings and canopies .17
8.5 Underground compressor installations .18
8.6 Hazardous area classification .18
9 Buffer storage .18
10 Dispensers . 19
10.1 General requirements .19
10.2 Breakaway devices .19
10.3 Fuelling hose assemblies . 20
10.4 Fuelling hoses .21
10.5 Enclosure . 22
10.6 Fuelling controls and instrumentation . 23
10.7 Electrical systems and interconnections .24
10.8 Documentation .24
11 Gas odorization.25
12 Pipework.25
12.1 General . 25
12.2 Buried piping . 26
13 Electrical .26
13.1 Labelling . 26
13.2 Contact with live parts . 26
13.3 Cables .27
13.4 Performance after power fail and restoration .27
13.5 Electrical bonding and grounding .27
14 Instrumentation and control system .27
14.1 Gas detection .27
15 Emergency shutdown .28
15.1 Emergency shutdown devices. 28
15.2 Emergency shutdown procedure . 29
15.3 Restoration after emergency shutdown . 29
16 Indoor fuelling .30
16.1 General . 30
16.2 Ventilation . 30

iii
oSIST prEN ISO 16923:2025
ISO/DIS 16923:2024(en)
16.3 Additional requirements . 30
17 Testing and commissioning .31
18 Operation .31
18.1 Fuelling procedures .31
18.2 Safety signs .31
18.3 Training .32
18.4 Emergency response plan . . 33
18.5 Operations manual . 33
19 Installation and operating instructions .33
20 Inspection and maintenance .34
20.1 Inspection and maintenance program . 34
20.2 Maintenance and testing frequency of gas detection . 34
Annex A (informative) Examples of hazardous zone classification .35
Annex B (normative) Separation distances .42
Annex C (informative) Fuelling procedures .43
Annex D (informative) Emergency instructions example .44
Annex E (informative) Example of fuelling station periodic inspection and maintenance .45
Bibliography . 47

iv
oSIST prEN ISO 16923:2025
ISO/DIS 16923:2024(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are 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 editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent
rights identified during the development of the document will be in the Introduction and/or on the ISO list of
patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment,
as well as information about ISO's adherence to the World Trade Organization (WTO) principles in the
Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html.
The committee responsible for this document is ISO/PC 340, Natural gas fuelling stations.

v
oSIST prEN ISO 16923:2025
oSIST prEN ISO 16923:2025
DRAFT International Standard ISO/DIS 16923:2024(en)
Natural gas fuelling stations — CNG stations for fuelling
vehicles
1 Scope
This document covers the design, construction, operation, inspection and maintenance of stations for
fuelling compressed natural gas (CNG) to vehicles, including equipment, safety and control devices.
This document also applies to portions of a fuelling station where natural gas is in a gaseous state and
dispensing CNG derived from liquefied natural gas (LCNG) according to ISO 16924.
This document applies to fuelling stations supplied with natural gas as defined in local applicable gas
composition regulations or ISO 13686. It also applies to other gases meeting these requirements including
biomethane, upgraded coal-bed methane (CBM) and gas supplies coming from LNG vaporization (on-site or
off-site).
This document includes all equipment for downstream gas supply connection (i.e. point of separation
between the CNG fuelling station piping and the pipeline network). Fuelling station nozzles are not defined
in this document.
This document covers fuelling stations with the following characteristics:
— slow fill;
— fast fill;
— private access;
— public access (self-service or assisted);
— fuelling stations with fixed storage;
— fuelling stations with mobile storage (daughter station);
— multi-fuel stations.
This document is not applicable to domestic CNG fuelling devices without buffer storage.
NOTE This document is based on the condition that the gas entering the fuelling station is odorized. For
unodorized gas fuelling stations, additional safety requirements are included in Clause 10.
2 Normative references
The following documents are referred to in 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 7-1, Pipe threads where pressure-tight joints are made on the threads — Part 1: Dimensions, tolerances and
designation
ISO 834-1, Fire-resistance tests — Elements of building construction — Part 1: General requirements
ISO 4126-1, Safety devices for protection against excessive pressure — Part 1: Safety valves
ISO 8580, Rubber and plastics hoses — Determination of ultra-violet resistance under static conditions

oSIST prEN ISO 16923:2025
ISO/DIS 16923:2024(en)
ISO 9809-1, Gas cylinders — Design, construction and testing of refillable seamless steel gas cylinders and tubes
— Part 1: Quenched and tempered steel cylinders and tubes with tensile strength less than 1 100 MPa
ISO 9809-2, Gas cylinders — Design, construction and testing of refillable seamless steel gas cylinders and
tubes — Part 2: Quenched and tempered steel cylinders and tubes with tensile strength greater than or equal to
1 100 MPa
ISO 11119-1, Gas cylinders — Design, construction and testing of refillable composite gas cylinders and tubes —
Part 1: Hoop wrapped fibre reinforced composite gas cylinders and tubes up to 450 l
ISO 11119-2, Gas cylinders — Design, construction and testing of refillable composite gas cylinders and tubes —
Part 2: Fully wrapped fibre reinforced composite gas cylinders and tubes up to 450 l with load-sharing metal liners
ISO 11119-3, Gas cylinders — Design, construction and testing of refillable composite gas cylinders and tubes
— Part 3: Fully wrapped fibre reinforced composite gas cylinders and tubes up to 450 l with non-load-sharing
metallic or non-metallic liners or without liners
ISO 11439, Gas cylinders — High pressure cylinders for the on-board storage of natural gas as a fuel for
automotive vehicles
ISO 11925-3, Reaction to fire tests — Ignitability of building products subjected to direct impingement of flame
— Part 3: Multi-source test
ISO 12100, Safety of machinery — General principles for design — Risk assessment and risk reduction
ISO 13847, Petroleum and natural gas industries — Pipeline transportation systems — Welding of pipelines
ISO 14120, Safety of machinery — Guards — General requirements for the design and construction of fixed and
movable guards
ISO 15500-2, Road vehicles — Compressed natural gas (CNG) fuel system components — Part 2: Performance
and general test methods
ISO 15500-17, Road vehicles — Compressed natural gas (CNG) fuel system components — Part 17: Flexible fuel line
ISO 15589-1, Petroleum, petrochemical and natural gas industries — Cathodic protection of pipeline systems —
Part 1: On-land pipelines
ISO 15649, Petroleum and natural gas industries — Piping
ISO 23684, Road vehicles — Technical personnel dealing with natural gas vehicles (NGVs) — Training and
qualification
ISO 20607, Safety of machinery — Instruction handbook — General drafting principles
ISO 24671, Road vehicles — Qualification and certification of technical personnel dealing with natural gas
vehicles (NGVs)
IEC 31010, Risk management — Risk assessment techniques
IEC 60079-0, Electrical apparatus for explosive gas atmospheres — Part 0: General requirements
IEC 60079-10-1, Explosive atmospheres — Part 10-1: Classification of areas — Explosive gas atmospheres
IEC 60079-11, Explosive atmospheres — Part 11: Equipment Protection by Intrinsic Safety “i”
IEC 60079-14, Electrical apparatus for explosive gas atmospheres — Part 14: Electrical installations in
hazardous areas (other than mines)
IEC 60079-25, Explosive atmospheres — Part 25: Intrinsically safe electrical systems
IEC 60079-29-1, Explosive atmospheres - Part 29-1: Gas detectors - Performance requirements of detectors for
fammable gases
oSIST prEN ISO 16923:2025
ISO/DIS 16923:2024(en)
IEC 60079-29-4, Explosive atmospheres - Part 29-4: Gas detectors - Performance requirements of open path
detectors for fammable gases
IEC 60079-32, Explosive atmospheres - Part 32-1: Electrostatic hazards, guidance
ISO 80079-36, Explosive atmospheres — Part 36: Non-electrical equipment for explosive atmospheres — Basic
method and requirements
IEC 60204-1, Safety of machinery — Electrical equipment of machines — Part 1: General requirements
IEC 60529, Degrees of protection provided by enclosures (IP Code)
IEC 62305 (series), Protection against lightning
IEC 62443 (series), Industrial communication networks – network and system security
EN 16723-2, Natural gas and biomethane for use in transport and biomethane for injection in the natural gas
network -part 2 – Automotive fuels specification
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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 http:// www .iso .org/ obp
3.1
assembly
sub-system of fuelling stations comprising several components
3.2
auto-extinguishing
feature of a material that ceases combustion upon removal of flame or ignition source
3.3
biomethane
methane rich gas derived from biogas or from gasification of biomass by upgrading with the properties
similar to natural gas
[SOURCE: ISO 14532:2014, 2.1.1.15]
3.4
bonding
equipotential zone where potentially live exposed metallic parts are electrically connected with at least one
point connected to ground/earth
3.5
breakaway device
a coupling which separates at a predetermined section to protect the fuelling station from damage by
vehicles driving away while still connected to the station.
Note 1 to entry: Each separated section contains a self-closing shut-off valve which seals automatically.
3.6
buffer storage
one or more suitable pressure vessels designed for the purpose of storing compressed natural gas

oSIST prEN ISO 16923:2025
ISO/DIS 16923:2024(en)
3.7
building
structures, usually enclosed by walls and a roof, constructed to provide support or shelter for an intended
occupancy
3.8
bundle tube
bundles of small diameter stainless steel tubes contained within a Polyethylene sheath
3.9
burst pressure
p pressure that causes failure and consequential fluid loss through the component envelope
b
3.10
canopy
roof, overhead shelter, or hood, that affords a degree of weather protection
3.11
CNG fuelling station
facility at which compressed natural gas is dispensed to vehicles
3.12
competent person
person having the ability, appropriate training, knowledge and experience, to supervise or carry out the
work being undertaken in a safe and proper manner with documented proof of appropriate training
3.13
compressed natural gas CNG
natural gas which has been compressed and stored for use as a vehicle fuel
[SOURCE: ISO 15500-1:2000, 3.2]
3.14
compressor
machine that increases the pressure of gas
3.15
conduit
casing, tubing or liner, either metallic or non-metallic
[SOURCE: ISO 14310:2008, 3.6]
3.16
cylinder
pressure vessel used for the storage of compressed natural gas
3.17
cylinder working pressure
settled pressure of a fully filled cylinder at a uniform temperature of 15 °C
3.18
dispenser
equipment through which the fuel is supplied to the vehicle
Note 1 to entry: This equipment can include metering.
3.19
Dryer
equipment which decreases the water vapour content (moisture) of natural gas

oSIST prEN ISO 16923:2025
ISO/DIS 16923:2024(en)
3.20
enclosure
structure, not being a building or canopy, that encloses a component of the fuelling station
EXAMPLE Housing, container and machine cabinet.
3.21
explosive gas atmosphere
mixture of substances with air, under atmospheric conditions, in the form of gases, vapours, mists or dusts
in which, after ignition has occurred, combustion spreads to the entire unburned mixture
[SOURCE: IEC 61340–4-4:2014, 11, 3.4]
3.22
fail-safe
design feature that ensures that safe conditions are maintained in the event of a malfunction of a control
device or an interruption of a supply source
3.23
fast fill
fuelling operation which has a designed flow rate greater than 100 m (N)/h per nozzle
3.24
field piping
piping installed for interconnection between equipment at the site
3.25
fire resistant
property that prevents or retards the passage of excessive heat, hot gases or flames under specified
conditions
3.26
fire wall
wall, or separating partition erected to reduce the effects of radiated heat
3.27
fuelling
transfer of fuel from dispenser to the vehicle
3.28
fuelling pressure
pressure at which the fuel is delivered to the vehicle
3.29
fuelling station
facility at which vehicles fuels are dispensed
3.30
grounding
electrical connection of potentially live exposed metallic parts to earth
3.31
hazardous area
area in which an explosive gas atmosphere is present, or can be expected to be present, in quantities such
as to require special precautions for the construction, installation and use of apparatus to prevent ignition
[SOURCE: IEC 60079–10–1:2008, 3.3]
3.32
hose
pipeline of flexible material with end fittings attached

oSIST prEN ISO 16923:2025
ISO/DIS 16923:2024(en)
3.32.1
vent hose
pipeline of flexible material through which natural gas is vented from the fuelling connection at a vehicle
3.31.2
hose assembly
hose or hoses with ancillary components, such as bend restrictors, breakaways and nozzles, attached
3.33
intrinsically safe circuit
circuit in which any spark or thermal effect is incapable of causing ignition of a mixture of flammable or
combustible material in air under specified test conditions
3.34
lower explosive limit
LEL
volume concentration of flammable gas or vapour in air, below which the mixture is not flammable
[SOURCE: ISO 19372:2015, 3.7, modified — “explosive” has been changed to “flammable”.]
3.35
maximum allowable operating pressure
MAOP
maximum pressure that the component or system is subjected to during normal operation
Note 1 to entry: MAOP is typically not greater than 90 % of the maximum allowable working pressure of the component
or system.
3.36
maximum allowable working pressure
MAWP
maximum pressure to which a component or system is designed to be subjected and which is the basis for
determining the strength of the component or system
[SOURCE: ISO 12991:2012, 3.10, modified — “or system” has been added and “under consideration” has been
removed.]
3.36.1
mobile storage
multi-cylinder or tank fixture mounted on a vehicle or trailer and used for the transportation of natural gas
to CNG fuelling stations
3.37
multi-fuel dispenser
dispenser delivering CNG and other fuels (liquid or gaseous)
3.38
multi-fuel station
fuelling station that can fuel natural gas as well as other fuels, for example diesel, petrol, LPG
3.39
natural gas
complex gaseous mixture of hydrocarbons, primarily methane, but generally includes ethane, propane and
higher hydrocarbons, and some non-combustible gases such as nitrogen and carbon dioxide
Note 1 to entry: Natural gas can also contain components or containments such as sulfur compounds and/or other
chemical species.
[SOURCE: ISO 14532:2014, 2.1.1.1]

oSIST prEN ISO 16923:2025
ISO/DIS 16923:2024(en)
3.40
non-combustible
not capable of undergoing combustion under specified conditions
[SOURCE: ISO 13943:2008, 4.239]
3.41
normal operation
situation when the equipment is operating within its design parameters
[SOURCE: ISO 16110-1:2007, 3.50]
3.42
non-hazardous area
area in which an explosive gas is not expected to be present in quantities such as to require special
precautions for the construction, installation and use of apparatus
[SOURCE: ISO 16110-1:2007, 3.48]
3.43
odorant
intensely smelling organic chemical or combination of chemicals added to natural gas at low concentration
and capable of imparting a characteristic and distinctive (usually disagreeable) warning odor so gas leaks
can be detected at concentrations below their lower flammability limit
Note 1 to entry: ISO/TR 16922 gives the specifications and guidelines for the methods to be used in the odorization of
natural gas under a safety point of view and specifies the principles for the odorization technique (including handling
and storage of odorants) and the control of odorization of natural gas.
[SOURCE: ISO 14532:2014, 2.8.1, modified — Note 1 to entry has been added.]
3.44
odorization
process of introducing odorant(s) into natural gas
3.45
overpressure
condition under which the pressure exceeds the maximum allowable working pressure
3.46
power failure
reduction in power such that any electrical component or sub system (such as flow control) are operating
outside manufacturers specification
3.47
refuelling receptacle
device connected to a vehicle or storage system which receives the CNG refuelling nozzle and permits
safe transfer of fuel
[SOURCE: ISO 14469-1:2004, 3.7]
3.48
separation distance
minimum separation between a hazard source and an object, which is required to mitigate the effect of a
likely foreseeable incident and prevent a minor incident escalating into a larger incident
3.48.1
external separation distance
separation distance between a hazard source and an object situated outside the boundaries of the fuelling station
3.48.2
internal separation distance
separation distance between a hazard source and an object situated within the boundaries of the fuelling station

oSIST prEN ISO 16923:2025
ISO/DIS 16923:2024(en)
3.49
service duct
enclosed conduit through which either field piping or electrical cabling is routed
3.50
settled pressure
gas pressure when a given settled temperature is reached and there is no gas flow
3.51
settled temperature
uniform gas temperature in the cylinder after the dissipation of any heat caused by fuelling
3.52
slow fill
fuelling operation which has a designed flow rate equal or less than 100 m (N)/h per nozzle
3.53
self service
facility where the fuel is dispensed by the user with or without supervision by an attendant.
3.54
vault
room or space, typically situated underground
3.55
ventilation
movement of air and its replacement with fresh air due to the effects of wind, temperature gradients, or
artificial means (for example fans or extractors)
3.56
venting
controlled release of natural gas to the atmosphere
3.57
zone
hazardous area classified based upon the frequency of the occurrence and duration of an explosive gas
atmosphere
[SOURCE: IEC 60079-10-1:2015, 3.3.3, modified — “gas” has been added.]
4 Symbols and abbreviated terms
4.1 Symbols
p
burst pressure
b
p
maximum allowable working pressure
MAWP
4.2 Abbreviated terms
CNG compressed natural gas
IS intrinsically safe
ERP emergency response plan
LEL lower explosive limit
MAOP maximum allowable operating pressure

oSIST prEN ISO 16923:2025
ISO/DIS 16923:2024(en)
MAWP maximum allowable working pressure
NGV natural gas vehicle
P&I process and instruments
5 Risk management
5.1 General
Risks shall be managed throughout the life cycle of the LNG fuelling station through the adoption of a
risk management policy and framework that systematically identifies, analyses and evaluates the risks
to personnel, the environment and equipment. The principles and guidelines of ISO 12100, ISO 31000 and
IEC 31010 shall be followed in developing a risk management policy and a risk management framework. One
or more of the risk assessment techniques described in IEC 31010 shall be used to conduct risk assessments.
Appropriate risk mitigation measures can then be identified and implemented to reduce the risks to as low
as reasonably practicable. Risk mitigation can be achieved through various measures to reduction of the
probability and/or the consequences of a risk scenario. Risk mitigation measures may include one or more
of the following:
a) the use of inherently safe designs and technologies;
b) the use of protective devices and systems;
c) the adoption of specific operating and maintenance procedures;
d) the use of personal protective equipment;
e) the provision of information and training;
f) the adoption of emergency planning and emergency procedures during the delivery process.
g) The need for an emergency stop system that can stop the filling process once activated, Including the
need for interaction with valves on the tube trailer or transportable module as applicable
h) the need to prevent public access during the delivery process
i) the need for isolation valves at the filling points
j) the measures taken to prevent excessive storage
k) the design of connection points to ensure a connection/disconnection suitable for transport storage and
site storage
l) the identification of losses during the delivery process
m) the protection against breakage of the flexible hose during transfer
n) the identification of hazardous areas around the delivery area
o) the flow control if applicable and
5.2 Risk assessment shall follow the techniques described in ISO 12100 for assessment of machinery
safety and IEC 31010 for general site risk management, or local applicable standards.
5.3 The CNG fuelling station installation shall be sited to minimize risk to users, operating personnel,
properties, and environment.
oSIST prEN ISO 16923:2025
ISO/DIS 16923:2024(en)
5.4 Risk assessment shall include design, construction, operation and maintenance of the CNG fuelling
station. The risk assessment process shall be used to evaluate the consequences of hazardous events and to
determine appropriate means of risk reduction and/or mitigation of consequences.
5.5 Measures to reduce fire and explosion risks shall be applied, including but not limited to:
— prevention of the formation of a flammable or explosive mixture;
— avoid electrostatic risk.
— avoid of ignition sources;
— mitigation of the effects of a fire or explosion.
5.6 Protection against static electricity shall be carried out according to applicable standards such as
IEC 60079-32-1 and ISO 80079-36, etc.
5.7 Protection from ignition in explosive atmospheres shall be by the use of protection systems defined in
the IEC 60079 series where the applicable hazard zones are defined in IEC 60079-10-1.
5.8 Hazardous area classification
5.8.1 A hazardous area classification analysis according to IEC 60079-10-1 shall be undertaken for all
the locations in which an explosive gas atmosphere can be present in quantities such as to require special
precautions in relation to electrical and other sources of ignition.
Note Annex A provides recommendations for determining the size of hazardous areas for the major units of the
CNG fuelling station.
5.8.2 Special attention shall be given to existing equipment such as high voltage cables and their insulation
and protection. Vaulted or underground installations shall be deemed to provide engineered protection
from overhead power lines.
5.8.3 if other combustible or hazardous liquids can encroach on any parts of the LNG fuelling station,
means shall be provided to protect those parts.
5.8.4 Fired equipment (flame heated equipment) shall be located outside hazardous areas.
5.8.5 The hazardous area shall not exceed the boundaries of the CNG fuelling station within the separation
distances as defined in Tables B.1 unless a complementary risk assessment is carried out.
5.9 General
5.9.1 Installation and equipment design shall minimize the number of connections and other possible
points of leakage or release to atmosphere.
5.9.2 Configurations generating the possibility of a confined explosive atmosphere should be avoided. Fire
and explosion risk prevention shall take into account foreseeable malfunctions and misuse.
5.9.3 Appropriate safety distances shall be maintained between the natural gas pipeline, and utility piping
and electrical cabling
5.9.4 Pressure indication shall be provided such that the pressure on any piping segment can be
determined.
oSIST prEN ISO 16923:2025
ISO/DIS 16923:2024(en)
5.9.5 Pressure piping system shall have provision for purging and safe manual depressurization.
Depressurization shall not be performed by opening pipe joints.
5.9.6 The mounting of equipment and supporting foundations shall be designed and constructed to be
suitable for local seismic and geological conditions.
5.9.7 All CNG equipment exposed to the risk of vehicle collision shall be provided with barriers or other
mechanisms to protect the gas equipment from collision damage.
5.9.8 The CNG fuelling station shall be designed to shut down safely in the event of a loss of power.
Restoration of power shall be in accordance with 16.2.
5.9.9 The CNG fuelling station shall include firefighting equipment in accordance with local applicable
regulations.
5.9.10 The CNG fuelling station shall have means of ensuring that oil carryover from the compressor, dust,
water in the gas stream are maintained within the limits of ISO 15403-1. Where specific limits are non
defined in ISO 15403-1, reference shall be made to locally applicable gas quality regulations and associated
standards.
5.9.11 All equipment shall be operated within temperature and pressure limits specified by the
manufacturer.
5.9.12 The CNG fuelling station shall be designed while taking into account the specific climatic conditions
of the site location and expected minimum and maximum temperatures.
5.9.13 During normal operation, venting should be limited to minor releases of gas resulting, for example,
from disconnection of hoses.
5.9.14 During vehicle fuelling, venting shall not be allowed, except when connecting and disconnecting
fuelling nozzle from vehicle receptacle where gas release to atmosphere is unavoidable.
5.10 Site layout
5.10.1 The CNG fuelling station separation distances shall follow the requirements listed in Annex B. At
multifuel stations the separation distances shall follow the requirements of applicable fuel standards. The
potential of hazardous interaction between different fuels shall be considered.
5.10.2 The
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