EN ISO 7291:2010

SLOVENSKI STANDARD
01-januar-2012
1DGRPHãþD
SIST EN ISO 7291:2002
Oprema za plamensko varjenje - Glavni regulatorji tlaka plina za varjenje, rezanje
in sorodne postopke za tlake do 30 MPa (300 bar) (ISO 7291:2010)
Gas welding equipment - Pressure regulators for manifold systems used in welding,
cutting and allied processes up to 30 MPa (300 bar) (ISO 7291:2010)
Gasschweißgeräte - Hauptstellendruckregler für Schweißen, Schneiden und verwandte
Prozesse bis 30 MPa (300 bar) (ISO 7291:2010)
Matériel de soudage aux gaz - Détendeurs de centrale de bouteilles pour le soudage, le
coupage et les techniques connexes jusqu'à 30 MPa (300 bar) (ISO 7291:2010)
Ta slovenski standard je istoveten z: EN ISO 7291:2010
ICS:
23.060.40 7ODþQLUHJXODWRUML Pressure regulators
25.160.30 Varilna oprema Welding equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 7291
NORME EUROPÉENNE
EUROPÄISCHE NORM
November 2010
ICS 25.160.30 Supersedes EN ISO 7291:2001
English Version
Gas welding equipment - Pressure regulators for manifold
systems used in welding, cutting and allied processes up to 30
MPa (300 bar) (ISO 7291:2010)
Matériel de soudage aux gaz - Détendeurs de centrale de Gasschweißgeräte - Hauptstellendruckregler für
bouteilles pour le soudage, le coupage et les techniques Schweißen, Schneiden und verwandte Prozesse bis 30
connexes jusqu'à 30 MPa (300 bar) (ISO 7291:2010) MPa (300 bar) (ISO 7291:2010)
This European Standard was approved by CEN on 23 October 2010.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same
status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2010 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 7291:2010: E
worldwide for CEN national Members.

Contents Page
Foreword .3

Foreword
This document (EN ISO 7291:2010) has been prepared by Technical Committee ISO/TC 44 "Welding and
allied processes" in collaboration with Technical Committee CEN/TC 121 “Welding” the secretariat of which is
held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by May 2011, and conflicting national standards shall be withdrawn at the
latest by May 2011.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 7291:2001.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 7291:2010 has been approved by CEN as a EN ISO 7291:2010 without any modification.

INTERNATIONAL ISO
STANDARD 7291
Third edition
2010-11-01
Gas welding equipment — Pressure
regulators for manifold systems used in
welding, cutting and allied processes up
to 30 MPa (300 bar)
Matériel de soudage aux gaz — Détendeurs de centrale de
bouteilles pour le soudage, le coupage et les techniques connexes
jusqu'à 30 MPa (300 bar)
Reference number
ISO 7291:2010(E)
©
ISO 2010
ISO 7291:2010(E)
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ii © ISO 2010 – All rights reserved

ISO 7291:2010(E)
Contents Page
Foreword .iv
1 Scope.1
2 Normative references.1
3 Terms and definitions .2
4 Units.3
4.1 Pressure .3
4.2 Flow.3
4.3 Temperature.3
5 Manufacturing requirements.3
5.1 Materials .3
5.2 Design, machining and assembly.4
6 Physical characteristics .6
6.1 General .6
6.2 Pressures .7
6.3 Flow rates.7
6.4 Operating characteristics .9
7 Marking.10
7.1 Pressure regulator.10
7.2 Pressure relief devices .10
8 Instructions for use.10
9 Type test procedure .11
9.1 General .11
9.2 Test conditions.11
9.3 Functional tests.12
9.4 Tests for mechanical resistance of pressure regulators .14
9.5 Test for durability of markings.18
Bibliography.19

ISO 7291:2010(E)
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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 7291 was prepared by Technical Committee ISO/TC 44, Welding and allied processes, Subcommittee
SC 8, Equipment for gas welding, cutting and allied processes.
This third edition cancels and replaces the second edition (ISO 7291:1999), which has been technically
revised.
Requests for official interpretations of any aspect of this International Standard should be directed to the
Secretariat of ISO/TC 44/SC 8 via your national standards body. A complete listing of these bodies can be
found at www.iso.org.
iv © ISO 2010 – All rights reserved

INTERNATIONAL STANDARD ISO 7291:2010(E)

Gas welding equipment — Pressure regulators for manifold
systems used in welding, cutting and allied processes up
to 30 MPa (300 bar)
1 Scope
This International Standard specifies requirements and test methods for pressure regulators in manifold
systems used in welding, cutting, and allied processes for:
1)
a) compressed gases up to 30 MPa (300 bar);
b) dissolved acetylene;
c) liquefied petroleum gases (LPG);
d) methylacetylene-propadiene-mixtures (MPS);
e) carbon dioxide (CO ).
[2]
It is not applicable to pressure regulators fitted directly to the gas cylinders, as defined in ISO 2503 .
2 Normative references
The following referenced documents are indispensable for the application 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 5171, Gas welding equipment — Pressure gauges used in welding, cutting and allied processes
ISO 9090, Gas tightness of equipment for gas welding and allied processes
ISO 9539, Gas welding equipment — Materials for equipment used in gas welding, cutting and allied
processes
ISO 15296, Gas welding equipment — Vocabulary — Terms used for gas welding equipment

1) The value 30 MPa relates to maximum cylinder filling pressure at 15 °C.
ISO 7291:2010(E)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 15296 and the following apply.
3.1
pressure regulator for manifold systems
device for regulating a generally variable inlet pressure to as constant as possible an outlet pressure when
controlling the output of a manifold of cylinders
NOTE The diagram of the pressure regulator is an example only. Optional design characteristics are to be
compatible with the safety requirements specified in this International Standard. See Figure 1.

Key
1 pressure regulator body
2 inlet connector
3 upstream pressure gauge
4 relief valve
5 downstream pressure gauge
6 outlet connector
7 pressure regulator cover
8 pressure adjusting screw
Figure 1 — Example of pressure regulators and designation of its components
3.2
manifold
assembly of devices generally linking two or more gas sources coupled to a user pipeline system, delivering a
regulated pressure under specified safe conditions
NOTE A manifold can include components like collectors, safety devices, and pressure regulators.
2 © ISO 2010 – All rights reserved

ISO 7291:2010(E)
4 Units
4.1 Pressure
2)
The pressures measured are gauge pressures and are expressed in megapascals or bars.
4.2 Flow
3)
Flow rates are measured in cubic metres per hour corrected to a standard atmosphere , taking into account
the relevant conversion coefficient for the gas used (see Table 1).
Table 1 — Conversion coefficient, U
Conversion coefficient
Test gas
LPG, e.g.
CO
air oxygen nitrogen argon hydrogen helium acetylene
propane
air 1 0,950 1,02 0,851 3,81 2,695 1,05 0,800 0,808
nitrogen 0,983 0,930 1 0,837 3,75 2,65 1,03 0,784 0,792

The conversion coefficient, U, is given by Equation (1):
γ
U = (1)
γ
where
γ is the density of test gas;
γ is the density of gas used.
4.3 Temperature
Temperatures are measured in degrees Celsius.
5 Manufacturing requirements
5.1 Materials
Materials for pressure regulators shall conform to the requirements of ISO 9539.

2) Pressure exceeding atmospheric pressure.
[1]
3) A standard atmosphere at 23 °C and 0,101 3 MPa (1,013 bar), ISO 554 .
ISO 7291:2010(E)
5.2 Design, machining and assembly
5.2.1 Oxygen pressure regulators
Pressure regulators for oxygen shall be designed and manufactured giving consideration to the possibility of
internal ignition. Pressure regulators for oxygen shall not ignite or show evidence of burning when submitted
to the ignition test in 9.4.4.
All components and accessories shall be thoroughly cleaned and degreased before assembly.
5.2.2 Acetylene pressure regulators
Pressure regulators shall be designed and constructed in such a way that they withstand acetylene
decomposition. The test shall be carried out in accordance with 9.4.6.
5.2.3 Connections
5.2.3.1 Inlet connections
Choice of inlet connections is left to the manufacturer's discretion.
5.2.3.2 Outlet connections
Choice of outlet connection is left to the manufacturer's discretion.
5.2.4 Filter
A particle filter, having an effective cross-section compatible with the discharge, shall be mounted within or
directly fitted to the pressure regulator upstream of the pressure regulator valve. The filter shall not be
removable without the use of a tool. The filter shall retain particles of size greater than or equal to 0,1 mm.
5.2.5 Pressure-adjusting device
This device shall be designed in such a way that it is not possible for the pressure regulator valve to be held in
the open position, for example, as a consequence of the spring being compressed fully (to its solid length).
If the dimensions of the pressure-adjusting screw are such as to prevent the spring becoming fully
compressed, then the pressure-adjusting screw shall not be removable.
Using the adjusting device, it shall not be possible to obtain a pressure at which the pressure relief device
vents.
5.2.6 Pressure gauges
The pressure regulator shall be supplied with upstream and downstream pressure gauges complying with the
functions and safety requirements specified in ISO 5171.
Inlet connection threads shall conform to international, regional or national standards for pressure gauges.
Pressure gauges shall be designed and constructed in such a way that they withstand acetylene
decomposition. The test shall be carried out in accordance with 9.4.7.
4 © ISO 2010 – All rights reserved

ISO 7291:2010(E)
5.2.7 Gas leakage
5.2.7.1 General
The pressure regulator shall be gastight to the exterior, e.g. to the atmosphere, and internally, i.e. between the
high-pressure and low-pressure parts. At all normal pressures for relevant gases, the leakage shall not
exceed the limits specified in 5.2.7.2 and 5.2.7.3.
5.2.7.2 External leakage
Pressure regulators shall be gastight to the atmosphere and shall conform to the requirements of ISO 9090.
The total leakage shall be less than 10 cm /h.
5.2.7.3 Internal leakage, q
f
Maximum allowable internal leakage, q , in cubic centimetres per hour, of the pressure regulator is a function
f
of its standard discharge, Q , in cubic metres per hour (see Figure 2).
3 3
For Q < 30 m /h, q < 50 cm /h and
1 f
3 3
for Q > 1 500 m /h, q < 2 500 cm /h.
1 f
Between these two pairs of values the allowable leakage rate shall satisfy Condition (2):
u  (2)
qQ
f1
Key
q internal leakage
f
Q standard discharge
Figure 2 — Allowable internal leakage rates
5.2.8 Mechanical resistance
5.2.8.1 Resistance to internal pressure
Pressure regulators shall be designed and constructed in such a way that the application of pressures given in
Table 2 in the high-pressure and low-pressure chambers does not lead to permanent deformation
(see 9.4.2.1).
ISO 7291:2010(E)
Table 2 — Test pressures
Gas High-pressure chambers Low-pressure chambers
Oxygen and other compressed gases,
p u 1 MPa (10 bar)
3 MPa (30 bar)
Acetylene
MPS
1,2 × 1,5 × p
Oxygen and other compressed gases,
6 MPa (60 bar)
1 MPa (10 bar) < p u 2 MPa (20 bar)
Oxygen and other compressed gases,
3p
p > 2 MPa (20 bar)
5.2.8.2 Pressure retention of the low-pressure side
Pressure regulators shall be designed and constructed so that if the low-pressure chamber of the pressure
regulator, or intermediate chamber in the case of two-stage pressure regulators, is in direct communication
with a full cylinder of gas, for example, the pressure regulator valve is held in the open position and the outlet
connection is closed by an attached stop valve or a blind plug, the high-pressure gas shall either be safely
retained or vented (see 9.4.2.2).
A pressure relief device may be fitted to the manifold pressure regulator to fulfil this requirement. For
flammable gases, a means of safely venting shall be provided.
6 Physical characteristics
6.1 General
The symbols used are given in Table 3.
Table 3 — Symbols used
Symbol Explanation
i irregularity coefficient
p pressure
p nominal inlet pressure
p nominal outlet pressure
p acetylene outlet pressure used for calculation of R (see 9.3.3.3)
2R
p acetylene outlet pressure used for calculation of i (see 9.3.5.3)
2i
p upstream pressure for type testing: p = 2 p + 1 (0,100 MPa)
3 3 2
p stabilized outlet pressure (stabilization after flow ceases)
p highest or lowest outlet pressure during a test of determination of irregularity coefficient according to 6.4.2
p inlet pressure
i
p outlet pressure
o
Q standard (nominal) discharge
Q maximum discharge
max
q internal leakage
f
R coefficient of pressure increase upon closure
t time
6 © ISO 2010 – All rights reserved

ISO 7291:2010(E)
6.2 Pressures
6.2.1 Nominal inlet pressure, p
Nominal inlet pressure specified by the manufacturer.
6.2.2 Nominal outlet pressure, p
Nominal outlet pressure for the standard discharge, Q , specified by the m
...