EN ISO 7291:2001

SLOVENSKI STANDARD
01-maj-2002
1DGRPHãþD
SIST EN 961:1996
Oprema za plamensko varjenje - Glavni regulatorji tlaka plina za varjenje, rezanje
in sorodne postopke za tlake do 300 bar (ISO 7291:1999)
Gas welding equipment - Pressure regulators for manifold systems used in welding,
cutting and allied processes up to 300 bar (ISO 7291:1999)
Gasschweißgeräte - Hauptstellendruckregler für Schweißen, Schneiden und verwandte
Prozesse bis 300 bar (ISO 7291:1999)
Matériel de soudage aux gaz - Détendeurs de centrales de bouteilles pour le soudage, le
coupage et les techniques connexes jusqu'a 300 bar (ISO 7291:1999)
Ta slovenski standard je istoveten z: EN ISO 7291:2001
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
August 2001
ICS 25.160.30 Supersedes EN 961:1995
English version
Gas welding equipment - Pressure regulators for manifold
systems used in welding, cutting and allied processes up to 300
bar (ISO 7291:1999)
Matériel de soudage aux gaz - Détendeurs de centrales de Gasschweißgeräte - Hauptstellendruckregler für
bouteilles pour le soudage, le coupage et les techniques Schweißen, Schneiden und verwandte Prozesse bis 300
connexes jusqu'à 300 bar (ISO 7291:1999) bar (ISO 7291:1999)
This European Standard was approved by CEN on 3 June 2001.
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 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 Management Centre has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,
Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2001 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 7291:2001 E
worldwide for CEN national Members.

Foreword
The text of the International Standard from Technical Committee ISO/TC 44 "Welding and
allied processes" of the International Organization for Standardization (ISO) has been taken
over as an European Standard by Technical Committee CEN/TC 121 "Welding", the
secretariat of which is held by DS.
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 February 2002, and conflicting national
standards shall be withdrawn at the latest by February 2002.
This European Standard replaces EN 961:1995.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium,
Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy,
Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United
Kingdom.
Endorsement notice
The text of the International Standard ISO 7291:1999 has been approved by CEN as a
European Standard without any modification.
NOTE: Normative references to International Standards are listed in annex ZA (normative).
Annex ZA (normative)
Normative references to international publications
with their relevant European publications
This European Standard incorporates by dated or undated reference, provisions from other
publications. These normative references are cited at the appropriate places in the text and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions
of any of these publications apply to this European Standard only when incorporated in it by
amendment or revision. For undated references the latest edition of the publication referred to
applies.
Publication Year Title EN Year
ISO 9090 1989 Gas tightness of equipment for gas EN 29090 1992
welding and allied processes
ISO 9539 1988 Materials for equipment used in gas EN 29539 1992
welding, cutting and allied processes
INTERNATIONAL ISO
STANDARD 7291
Second edition
1999-12-01
Gas welding equipment — Pressure
regulators for manifold systems used in
welding, cutting and allied processes up to
300 bar
Matériel de soudage aux gaz — Détendeurs de centrales de bouteilles pour
le soudage, le coupage et les techniques connexes jusqu'à 300 bar
A
Reference number
ISO 7291:1999(E)
ISO 7291:1999(E)
Contents Page
1 Scope .1
2 Normative references .1
3 Terms and definitions .1
4 Terminology.1
5 Symbols and units.2
6 Manufacturing requirements .3
7 Types of connection.6
8 Physical characteristics.6
9 Type test procedure.9
10 Marking .15
11 Instructions for use .15
Annex A (informative) Decomposition test for pressure regulators in manifolds used for acetylene .16
Bibliography.17
©  ISO 1999
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet iso@iso.ch
Printed in Switzerland
ii
© ISO
ISO 7291:1999(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 3.
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.
International Standard 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 second edition cancels and replaces the first edition (ISO 7291:1990) which has been technically revised.
Annex A of this International Standards is for information only.
iii
INTERNATIONAL STANDARD  © ISO ISO 7291:1999(E)
Gas welding equipment — Pressure regulators for manifold
systems used in welding, cutting and allied processes up to
300 bar
1 Scope
This International Standard specifies requirements and test methods for pressure regulators in manifold systems for
welding, cutting and allied processes.
This International Standard is applicable to pressure regulators normally used for compressed gases up to 300 bar
(30 MPa), for dissolved acetylene, methylacetylene-propadiene-mixtures (MPS) and carbondioxide (CO ), to
regulate the pressure at the outlet of high-pressure lines from manifold gas cylinders.
It is not applicable to pressure regulators fitted directly to the gas cylinders, as defined in ISO 2503 or to pressure
regulators for liquefied petroleum gases.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 554:1976, Standard atmospheres for conditioning and/or testing — Specifications.
ISO 5171:1995, Pressure gauges used in welding, cutting and allied processes.
ISO 9090:1989, Gas tightness of equipment for gas welding and allied processes.
ISO 9539:1988, Materials for equipment used in gas welding, cutting and allied processes.
3 Terms and definitions
For the purposes of this International Standard, the following term and definition apply.
3.1
pressure regulator for manifold systems
device for regulating a generally variable inlet pressure to as constant as possible an outlet pressure, and intended
to equip a manifold of cylinders
4 Terminology
Figure 1 shows a diagram of the pressure regulator as an example only. Optional design characteristics shall be
compatible with the safety requirements specified in this International Standard.
© ISO
ISO 7291:1999(E)
Key
1 Pressure regulator housing 5 Outlet connection
2 Inlet connection 6 Pressure regulator bonnet
3 Pressure gauges 7 Pressure adjusting screw
4 Relief valve
Figure 1 — Example of pressure regulators and designation of its components
5 Symbols and units
5.1 Symbols
The symbols used in this International Standard are listed in Table 1.
Table 1 — Symbols used
Symbol Designation
i Irregularity coefficient
p Rated inlet pressure
p Rated outlet pressure
p Acetylene outlet pressure used for calculation of i (see 9.4.5)
2i
p Acetylene outlet pressure used for calculation of R (see 9.4.4)
2R
p
3 Upstream pressure for type testing: p = 2p + 1 bar (0,1 MPa)
3 2
p Stabilised outlet pressure (stabilisation 1 min after flow ceases)
p Highest or lowest outlet pressure during a test of determination of irregularity coefficient in
accordance with 9.4.5
Q Nominal discharge
Q Maximum discharge
max
Q Discharge of the relief valve
RV
Coefficient of pressure increase upon closure
R
T Internal leakage
f
Conversion coefficient
U
© ISO
ISO 7291:1999(E)
5.2 Units
5.2.1 Pressure
1) -1
The pressures measured are gauge pressures and are expressed in bar (10 MPa).
5.2.2 Flow
3 2)
Flow rates are measured in cubic metres per hour (m /h) at normal conditions taking into account the relevant
conversion coefficient for the gas used (see Table 2).
Table 2 — Conversion coefficient, U
Test
Conversion coefficient for
gas
air oxygen nitrogen argon hydrogen helium acetylene CO
Air 1 0,95 1,02 0,851 3,81 2,695 1,05 0,808
Nitrogen 0,983 0,93 1 0,837 3,75 2,65 1,03 0,792
Conversion coefficient, U, based on the formula:
g
U
g
where
g is the specific weight of test gas;
g is the specific weight of gas used.
5.2.3 Temperature
Temperatures are measured in degrees Celsius (°C).
6 Manufacturing requirements
6.1 Materials
Materials for pressure regulators shall be in accordance with ISO 9539.
6.2 Design, machining and assembly
6.2.1 Oxygen pressure regulators
Pressure regulators for oxygen shall be designed, machined and manufactured to withstand an adiabatic
compression test (see 11.5.3). All components and accessories shall be thoroughly cleaned and degreased before
assembly.
1)
Pressure greater than atmospheric pressure.
2)
Normal conditions are given in ISO 554.
© ISO
ISO 7291:1999(E)
6.2.2 Acetylene pressure regulators
Pressure regulators for acetylene shall be designed and constructed in such a way that they withstand any
acetylene decomposition.
...