prEN ISO 17879

SLOVENSKI STANDARD
01-marec-2026
Plinske jeklenke - Samozaporni ventili za plinske jeklenke - Specifikacija in
preskus tipa (ISO/DIS 17879:2026)
Gas cylinders - Self-closing cylinders valves - Specification and type testing (ISO/DIS
17879:2026)
Gasflaschen - Selbstschließende Flaschenventile - Spezifikation und Baumusterprüfung
(ISO/DIS 17879:2026)
Bouteilles à gaz - Robinets de bouteilles équipés de clapets auto-obturants -
Spécifications et essais de type (ISO/DIS 17879:2026)
Ta slovenski standard je istoveten z: prEN ISO 17879
ICS:
23.020.35 Plinske jeklenke Gas cylinders
23.060.40 Tlačni regulatorji Pressure regulators
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
International
Standard
ISO/DIS 17879
ISO/TC 58/SC 2
Gas cylinders — Self-closing
Secretariat: AFNOR
cylinders valves — Specification and
Voting begins on:
type testing
2026-01-15
ICS: 23.020.35
Voting terminates on:
2026-04-09
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,
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USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
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RECIPIENTS OF THIS DRAFT ARE INVITED
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NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION.
Reference number
ISO/DIS 17879:2026(en)
DRAFT
ISO/DIS 17879:2026(en)
International
Standard
ISO/DIS 17879
ISO/TC 58/SC 2
Gas cylinders — Self-closing
Secretariat: AFNOR
cylinders valves — Specification and
Voting begins on:
type testing
ICS: 23.020.35
Voting terminates on:
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 2026
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
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Published in Switzerland Reference number
ISO/DIS 17879:2026(en)
ii
ISO/DIS 17879:2026(en)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Valve description . 8
5 Valve design requirements . 9
5.1 General .9
5.2 Materials .9
5.3 Valve connections .10
5.4 Mechanical strength .11
5.4.1 Resistance to hydraulic pressure .11
5.4.2 Resistance to mechanical damage . 12
5.5 Valve operating mechanism. 12
5.5.1 Opening and closing of the valve. 12
5.5.2 Endurance . 12
5.5.3 Acetylene specific requirements . 13
5.6 Leakage . 13
5.7 Resistance to ignition .14
5.8 Manufacturing tests and examinations .14
6 Type testing . 14
6.1 General .14
6.2 Test schedule .14
6.3 Documentation .17
6.4 Test samples .17
6.5 Test report .18
6.6 Test temperatures .18
6.7 Test pressures .18
6.7.1 Valve hydraulic test pressure.18
6.7.2 Valve test pressure .18
6.8 Test gases.19
6.8.1 Gas quality .19
6.8.2 Leak tightness tests . 20
6.8.3 Endurance test . 20
6.8.4 Acetylene decomposition test . 20
6.8.5 Oxygen pressure surge test . 20
6.9 Hydraulic pressure test . 20
6.10 Leak tightness tests .21
6.10.1 General .21
6.10.2 Internal leak tightness test .21
6.10.3 External leak tightness test . 22
6.11 Endurance test . 22
6.12 Endurance test of VIPR type C . 23
6.13 Endurance test of the filling connection non-return valve .24
6.13.1 Filling connection non-return valve downstream of the valve operating
mechanism .24
6.13.2 Filling connection non-return valve upstream of the valve operating mechanism . 25
6.13.3 Test apparatus . 25
6.14 Visual examination . 26
6.15 Pressure relief valve tightness test . 26
7 Marking . .27
Annex A (normative) Mechanical strength tests .28

iii
ISO/DIS 17879:2026(en)
Annex B (normative) Oxygen pressure surge test .31
Annex C (normative) Required tests for validation of changes and/or material variants within
a valve design .33
Annex D (informative) Example of a vacuum test .35
Annex E (normative) Manufacturing tests and examinations .36
Bibliography .37

iv
ISO/DIS 17879:2026(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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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 voluntary nature of standards, 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 www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 58, Gas cylinders, Subcommittee SC 2, Cylinder
fittings, in collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/
TC 23, Transportable gas cylinders, in accordance with the Agreement on technical cooperation between ISO
and CEN (Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 17879:2017), which has been technically
revised.
The main changes are as follows:
— Harmonization with the 2024 edition of ISO 10297;
— Modification of requirements and testing of valves used in acetylene service including deletion of former
Annex B;
— Update of Annex B (former Annex C) on the oxygen pressure surge test by adopting the structure of the
respective Annex C in ISO 10297:2024.
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.

v
ISO/DIS 17879:2026(en)
Introduction
This document has been written so that it is suitable to be referenced in the UN Model Regulations. In this
document, the unit bar is used due to its universal use in the field of technical gases. It should, however, be
5 5 2
noted that bar is not an SI unit, and that the corresponding SI unit for pressure is Pa (1 bar = 10 Pa = 10 N/m ).
Pressure values in this document are given as gauge pressure (pressure exceeding atmospheric pressure)
unless noted otherwise.
Any tolerances given in this document include measurement uncertainties.

vi
DRAFT International Standard ISO/DIS 17879:2026(en)
Gas cylinders — Self-closing cylinders valves — Specification
and type testing
1 Scope
This document specifies design, type testing, marking and manufacturing tests and examinations
requirements for:
a) self-closing cylinder valves;
b) self-closing cylinder valves with integrated pressure regulator (VIPR);
NOTE 1 This includes VIPR designs where the primary valve operating mechanism is located upstream of the
pressure regulating system (VIPR type A) and where the primary valve operating mechanism is located at the
low-pressure side of the pressure regulating system (VIPR type C).
NOTE 2 This does not include VIPR designs where the pressure regulating system is acting as the primary
valve operating mechanism (VIPR type B) and designs where closure of the primary valve operating mechanism
is obtained by closing the seat of the pressure regulating mechanism. Such designs are covered by ISO 10297.
for refillable transportable gas cylinders which convey compressed, liquefied or dissolved gases.
NOTE 3 The main applications for such self-closing cylinder valves are in the calibration gas and beverage
industries.
NOTE 4 Where there is no risk of ambiguity, cylinder valves and VIPRs are addressed with the collective term
“valves” within this document.
This document does not apply to:
— valves for cryogenic equipment, portable fire extinguishers and liquefied petroleum gas (LPG);
— quick-release cylinder valves (e.g. for fire-extinguishing, explosion protection and rescue applications)
- requirements for quick-release cylinder valves are specified in ISO 17871 which contains normative
references to this document;
— ball valves.
NOTE 5 Requirements for valves for cryogenic vessels are specified in ISO 21011 and at a regional level, e.g. in
EN 1626. Requirements for valves for portable fire extinguishers are specified at a regional level, e.g. in EN 3 series.
Requirements for self-closing LPG cylinder valves are specified in ISO 14245. Requirements for quick-release cylinder
valves are given in ISO 17871. Requirements for ball valves are given in ISO 23826.
This document only covers the function of a valve as a closure. Other functions that are possibly integrated
in the valve can be covered by other standards. Such standards do however not constitute requirements
according to this document.
NOTE 6 Definition of and specific requirements for VIPRs in addition to those that are given in this document are
specified in ISO 22435 for industrial applications or ISO 10524-3 for medical applications. Similarly, certain specific
additional requirements for residual pressure valves (RPV) are given in ISO 15996.
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/DIS 17879:2026(en)
ISO 10286, Gas cylinders — Vocabulary
ISO 10297:2024, Gas cylinders — Cylinder valves — Specification and type testing
ISO 11114-1, Gas cylinders — Compatibility of cylinder and valve materials with gas contents — Part 1: Metallic
materials
ISO 11114-2, Gas cylinders — Compatibility of cylinder and valve materials with gas contents — Part 2: Non-
metallic materials
ISO 11114-6, Gas cylinders — Compatibility of cylinder and valve materials with gas contents — Part 6: Oxygen
pressure surge testing
ISO 13341, Gas cylinders — Fitting of valves to gas cylinders
ISO 14246, Gas cylinders — Cylinder valves — Manufacturing tests and examinations
ISO 15615:2022, Gas welding equipment — Acetylene manifold systems for welding, cutting and allied processes
— Safety requirements in high-pressure devices
3 Terms and definitions
For the purposes of this document, the terms and definitions in ISO 10286 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
self-closing cylinder valve
cylinder valve with a normally closed valve operating mechanism (3.9) that is actuated by a separate operating
device (3.10) which is not an integral part of the cylinder valve
3.2
residual pressure valve
RPV
valve which incorporates a residual pressure device (3.3)
3.3
residual pressure device
RPD
device that is designed to prevent ingress of contaminants by maintaining a positive pressure within the gas
cylinder relative to atmosphere by closing off its internal gas passages in the discharging direction
Note 1 to entry: This definition can be different to definitions given in applicable transport regulations.
3.4
valve with integrated pressure regulator
VIPR
device intended to be permanently fitted to a gas cylinder which comprises of at least a shut-off function and
pressure regulating system
3.5
VIPR type A
VIPR design where the primary valve operating mechanism (3.9) is located upstream of the pressure
regulating system (3.8)
Note 1 to entry: For typical designs, see Figure 1.

ISO/DIS 17879:2026(en)
a) Valve filling connection upstream of the prima- b) Valve filling connection between the primary
ry valve operating mechanism valve operating mechanism and the pressure
regulating system
Key
1 valve inlet connection
2 primary valve operating mechanism
3 valve filling connection
4 filling connection closing device
5 pressure regulating system
6 valve outlet connection
Figure 1 — General structure of VIPR type A designs
3.6
VIPR type B
VIPR design where the pressure regulating system (3.8) is also acting as the primary valve operating
mechanism (3.9)
Note 1 to entry: See Figure 2.

ISO/DIS 17879:2026(en)
Key
1 valve inlet connection
2 pressure regulating system including primary valve operating mechanism
3 valve filling connection
4 filling connection closing device
5 valve outlet connection
Figure 2 — General structure of a VIPR type B design
3.7
VIPR type C
VIPR design where the primary valve operating mechanism (3.9) is located downstream of the pressure
regulating system (3.8)
Note 1 to entry: The primary valve operating mechanism can be a flow selector.
Note 2 to entry: See Figure 3.

ISO/DIS 17879:2026(en)
Key
1 valve inlet connection
2 primary valve operating mechanism
3 valve filling connection
4 filling connection closing device
5 pressure regulating system
6 valve outlet connection
Figure 3 — General structure of a VIPR type C design
3.8
pressure regulating system
device(s) that reduce(s) the inlet pressure to a controlled outlet pressure
Note 1 to entry: A pressure regulating system can comprise of one or more stages of pressure regulation.
Note 2 to entry: The pressure regulating system can be either adjustable (adjustable pressure setting) or pre-set
(fixed pressure setting).
3.9
valve operating mechanism
mechanism which opens the valve orifice by an operating device (3.10) and closes automatically when or
before the operating device is disconnected and which includes the internal sealing system
3.10
operating device
external component which actuates the valve operating mechanism (3.9)
Note 1 to entry: The operating device is not part of the valve design.
EXAMPLE Push-pin as part of a regulator, lever-operated push-pin.
3.11
external leak tightness
leak tightness to atmosphere (leakage in and/or leakage out) when the valve is open
Note 1 to entry: Some designs of self-closing valves (e.g. Figure 6 a)) cannot leak externally except through the valve
outlet connection.
Note 2 to entry: The total external leakage typically comprises that from the valve external sealing system plus, for
example, pressure relief device, RPD, pressure indicating devices and pressure regulating system.

ISO/DIS 17879:2026(en)
Note 3 to entry: See Figure 4.
Note 4 to entry: Leakage in describes a leak resulting in a flow direction into the valve during vacuum testing. Leakage
out describes a leak resulting in a flow direction out of the valve.
a) p < p b) p > p
a a
Key
1 valve outlet connection (sealed)
p internal pressure
p atmospheric pressure
a
a
Leakage in (vacuum test).
b
Leakage out.
Figure 4 — External leak tightness
3.12
internal leak tightness
leak tightness to atmosphere (leakage in and/or leakage out) when the valve is closed and pressurized from
the valve inlet connection
Note 1 to entry: See Figure 5.
Note 2 to entry: Leakage in describes a leak resulting in a flow direction into the valve during vacuum testing. Leakage
out describes a leak resulting in a flow direction out of the valve.

ISO/DIS 17879:2026(en)
a) p < p b) p > p
a a
Key
1 valve outlet connection (open)
p internal pressure
p atmospheric pressure
a
a
Leakage in (vacuum test).
b
Leakage out.
Figure 5 — Internal leak tightness
3.13
leak tightness in transport and storage conditions
leak tightness across any closing device (e.g. valve seat, filling connection closing device, outlet connection
closing device) and integrated pressure retaining components (e.g. active pressure gauge, pressure relief
device) located upstream of the closing device, when the valve is closed
Note 1 to entry: For valves without any integrated pressure retaining components located upstream the valve seat,
the leak tightness in transport and storage conditions corresponds to the internal leak tightness (3.12).
3.14
valve working pressure
p
w
settled pressure of a compressed gas at a uniform reference temperature of 15 °C in a full gas cylinder for
which the valve is intended
Note 1 to entry: This definition does not apply to liquefied gases (e.g. carbon dioxide) or dissolved gases (e.g. acetylene).
3.15
valve hydraulic test pressure
p
vht
minimum pressure applied to a valve during the hydraulic pressure test
3.16
valve test pressure
p
vt
minimum pressure applied to a valve during testing

ISO/DIS 17879:2026(en)
3.17
total package mass
combined mass of a gas cylinder, its valve(s), its permanent attachment(s) and its maximum allowed gas content
Note 1 to entry: Valve guards but not valve protection caps are examples of permanent attachments.
Note 2 to entry: The total package mass is expressed in kg.
3.18
valve inlet connection
connection on the valve which connects the valve to the cylinder
3.19
valve outlet connection
connection on the valve used to discharge the cylinder
Note 1 to entry: For most valves, this connection is also used for filling the cylinder.
3.20
valve filling connection
connection on the valve used to fill the cylinder
Note 1 to entry: For some valves, the valve filling connection is different from the valve outlet connection.
3.21
filling connection closing device
closing device located in the valve filling connection (3.20)
EXAMPLE Non-return valve, isolating valve.
4 Valve description
4.1 A self-closing valve typically comprises:
a) valve body;
b) valve operating mechanism;
c) valve outlet connection(s);
d) valve inlet connection.
4.2 Valves can also incorporate:
a) pressure-relief device;
NOTE The relevant transport regulation can require or forbid pressure relief devices for some gases, gas
mixtures or gas groups. Additional requirements for pressure relief devices can exist in international/regional
regulations/standards.
b) dip tube;
c) outlet connection plug/cap;
d) excess flow device;
e) filling connection closing device (e.g. non-return valve, isolating valve);
f) RPD with or without non-return function;
g) pressure regulating system;
h) separated valve filling connection (i.e. separated from the valve outlet connection, e.g. for a VIPR);

ISO/DIS 17879:2026(en)
e) flow restricting orifice;
f) filter(s).
Not all of these components have test requirements detailed in this document.
4.3 Typical self-closing cylinder valve designs are given in Figure 6.
a) b)
Key
1 poppet
2 valve body
3 seat insert/soft seal
4 seat closing spring
Figure 6 — Typical self-closing cylinder valve designs
5 Valve design requirements
5.1 General
Valves shall be designed to open and close and be leak tight from −20 °C to +65 °C. In the closed position, valves
shall be leak tight during transport and storage (see test no. 6 in Table 2) for temperatures down to −40 °C.
The design requirements given in Clause 5 are minimum requirements to be met. The agreement of stricter
requirements is permitted.
5.2 Materials
Under all intended operating conditions [see 6.3 e)], metallic and non-metallic materials in contact with the
gas shall be chemically and physically compatible with the gas, either
— according to ISO 11114-1 and ISO 11114-2 or

ISO/DIS 17879:2026(en)
— proven as being compatible, see 6.3 f).
Copper alloys in contact with oxygen or other oxidizing gases or gas mixtures shall have a maximum
aluminium content of no more than 2,5 %.
The compatibility of the lubricant(s) and adhesive(s), if used in gas wetted areas, shall also be considered.
For valves used for dissolved gases, the compatibility of the materials in contact with the solvent shall also
be considered.
For valves used with gas mixtures, the compatibility of the gas wetted materials with each component of the
gas mixture shall be considered.
When using plated or coated components in gas wetted areas, the material compatibility of both, the plating/
coating material and the substrate material shall be taken into account. In addition, consideration should
be given to avoid flaking or particle generation, especially for oxygen, other oxidizing gases (as defined in
ISO 10156) and gas mixtures containing oxygen or other oxidizing gases.
The material used for the valve body shall be of either:
a) a metallic material not showing a ductile to brittle transition (examples of materials not showing a
ductile to brittle transition are copper alloys, austenitic stainless steels, aluminium alloys and nickel
alloys), or
b) a ferritic material (e.g. carbon steel) having an impact value greater than 27 J at −40 °C when submitted
to the Charpy pendulum impact test as specified in ISO 148-1.
For valves requiring oxygen pressure surge testing (see 5.7), ignition resistance of non-metallic materials,
lubricants and adhesives used in the gas wetted area of valves should be considered (e.g. using an appropriate
test procedure such as ISO 11114-3 for auto ignition temperature (AIT) testing and ISO 21010:2014, Annex C
for oxygen pressure surge testing of materials using test apparatus as given in ISO 11114-6). Non-metallic
materials used in oxygen wetted areas should have an AIT of at least 100 °C above its maximum service
1)
temperature tested at a pressure of at least 100 bar (see ISO 15001 or ASTM G63).
Lubricants used in all gas wetted area of valves (e.g. for VIPR also the lubricants used downstream the
pressure regulating system) for gases requiring oxygen pressure surge testing (see 5.7) shall either
1) be rated for:
— at least p in cases of single gases, or
vt
— a pressure not less than the corresponding oxygen partial pressure in case of gas mixtures containing
other oxidizing gases than air with a partial pressure greater than 30 bar, or
NOTE This rated pressure is the maximum pressure at which the lubricant passed the oxygen pressure
surge test described in ISO 21010:2014, Annex C.
2) be permitted only if the corresponding valve passes the oxygen pressure surge test after being pre-
conditioned via the endurance cycling procedure described in 6.11 but without subsequent leak
tightness tests and without visual examination being performed.
For medical and breathing applications ISO 15001 should be considered, especially when selecting materials
to reduce the risk of toxic products of combustion/decomposition from non-metallic materials including
lubricants.
5.3 Valve connections
If the valve connections are not an integral part of the valve body, the design shall ensure that they cannot
be unintentionally disassembled.
1) 1 bar = 0,1 MPa = 105 Pa; 1 MPa = 1 N/mm2.

ISO/DIS 17879:2026(en)
Valve inlet and outlet connections shall conform to:
— an International Standard or
— regional or national standards or
— proprietary designs that have been qualified to an acceptable industry standard.
If the valve outlet connection is also used as valve filling connection, the filling mechanism shall be designed
so that it does not encroach or compromise safe gas withdrawal via user connectors in accordance with a
relevant standard.
NOTE 1 International valve inlet connection standards are, for example, ISO 11363-1 and ISO 15245-1.
NOTE 2 International valve outlet connection standards are, for example, ISO 5145 and ISO 10692-1. A partial
compilation of regional and national standards is given in ISO/TR 7470. For medical VIPRs, see ISO 10524-3.
NOTE 3 Qualification procedures for proprietary valve inlet connection designs are, for example, given in
ISO 10692-2.
NOTE 4 Qualification procedures for proprietary valve outlet connection designs are, for example, given in CGA V-1.
Specific measures shall be taken if the valve filling connection is separated from the valve outlet connection
in one of the ways given as a) and b).
a) If the valve filling connection is located between the valve operating mechanism and the gas cylinder
[e.g. see Figures 1 a) and Figure 3], it shall be equipped with a filling connection closing device (i.e. non-
return valve or isolating valve).
b) If the valve filling connection is located between the valve operating mechanism and the valve outlet
connection [e.g. see Figure 1 b)], it shall be provided either with a filling connection closing device (i.e.
non-return valve or isolating valve) or with a pressure-tight device (e.g. a plug or cap which can be
operated or removed only by the use of a special proprietary tool provided by the manufacturer). If
fitted, such a pressure-tight device shall be designed to vent gas before becoming disengaged.
If a non-return valve is used, it shall meet the requirements of 5.6 without replacement of the sealing system
after 1 000 opening and closing cycles.
The endurance test of the filling connection non-return valve is given in 6.13.
If an isolating valve is used, it shall meet all requirements for the valve operating mechanism of the
applicable closure standard (e.g. Clause 5.5 of this document or equivalent Clause in ISO 10297 or ISO 23826),
except that for the endurance test only 1 000 cycles shall be applied. Such isolating valves may be tested in
combination with testing the valve operating mechanism.
NOTE 5 The reduction of the number of cycles to 1 000 cycles is based on the estimation that the filling connection
is operated less frequently than the valve operating mechanism.
5.4 Mechanical strength
5.4.1 Resistance to hydraulic pressure
Valves shall withstand p (see 6.7.1) without burst.
vht
The hydraulic burst pressure test is specified in 6.9.
NOTE The hydraulic pressure test confirms whether the burst pressure of the valve is at least 1,5 times the test
pressure of the gas cylinder, which can be required by transport regulations (e.g. UN Model Regulations).
For valves for acetylene service see 5.5.3.2.

ISO/DIS 17879:2026(en)
5.4.2 Resistance to mechanical damage
Valves shall be tested for resistance to mechanical damage, if:
a) used for gas cylinders not intended to be protected during transport by
— a valve protection cap or a valve guard complying with ISO 11117, or
— other suitable means;
NOTE Applicable transport regulations normally specify the variety of suitable means to maintain the
integrity of the gas cylinder.
b) used for gas cylinders where a valve guard is fixed only to the valve and not to the gas cylinder. The
valve shall be tested without the valve guard fitted.
The valve shall withstand the impact test according to Annex A, A.1.
Distortion due to impact is permissible. After being tested, for safety reasons, the closed valve shall first be
pressurized hydraulically to p and not burst or leak. If successfully passed, the closed valve shall undergo
vt
a pneumatic leak tightness test at p with the outlet unplugged. The total leakage (comprising that from the
vt
valve internal sealing system plus that from the threaded joint between the valve and the gas cylinder/test
fixture) shall not exceed 100 cm /h. Any leakage shall not result from cracking of the valve body. In addition,
the test sample shall remain capable of being opened for emergency venting purposes, e.g. by using a tool.
If the dimensions of the valve make the impact test impracticable, then the drop test according to Annex A,
A.2 shall be carried out. After the drop test, the valve shall be leak tight as specified in Annex A, A.2. Any
leakage shall not result from cracking of the valve body. In addition, the test sample shall remain capable of
being opened for emergency venting purposes, e.g. by using a tool.
Note The test is deemed to be impracticable when the dimensions of the plummet weight collide with the
cylinder neck or test fixture and not just with the valve.
5.5 Valve operating mechanism
5.5.1 Opening and closing of the valve
The valve operating mechanism should be designed in such a way that the setting of the operating position
of the valve cannot be inadvertently altered, i.e. if the valve is closed, it should remain closed during normal
service or normal transport.
Valves for gases requiring oxygen pressure surge testing (see 5.7) or for acetylene service should have an
opening characteristic which avoids rapid pressure surge. This can be achieved using flow limiting devices.
NOTE Valve opening characteristic is the time needed to equalise the pressure upstream and downstream of
the valve seat after opening the valve operating mechanism. This time varies with the design of the valve operating
mechanism and the volume downstream of the valve seat.
5.5.2 Endurance
The valve operating mechanism shall meet the requirements of 5.6 without replacement of the sealing
system after 2 000 opening and closing cycles.
For a VIPR type C with more than one valve operating mechanism (e.g. pressure outlet and flow selector),
each valve operating mechanism shall be tested.
It shall be possible to open and close the valve at pressures up to p (see 6.7.2) without using any additional
vt
equipment not recommended by the manufacturer. This shall be verified during the endurance test, see 6.11.
In addition, VIPR type C shall meet the requirements of 5.6 without replacement of the sealing system after
100 000 opening and closing cycles.

ISO/DIS 17879:2026(en)
The additional endurance test of VIPR type C is given in 6.12.
After the endurance test(s) and the subsequent leak tightness tests have been performed, a visual
examination shall be carried out to ensure that no components are displaced (no longer in the places where
they were installed), non-functional (e.g. broken) or missing.
The visual examination is specified in 6.14.
5.5.3 Acetylene specific requirements
5.5.3.1 General
For valves for acetylene service, a means to protect the valve seat from contamination coming from the
cylinder shall be fitted.
Note A mesh or sintered filter of 100 µm filtration capability installed in the valve inlet has proved to be
adequate.
5.5.3.2 Resistance to acetylene flashback
To verify resistance to acetylene flashback for valves for acetylene service, self-closing valves shall undergo
an acetylene decomposition test as a stop valve in accordance with ISO 15615:2022, Annex A, Table A.1 via
the outlet connection in the open position. Due to the developed pressure involved in decomposition, this
test is deemed to be sufficient to prov
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