ISO 14520-1:2015

Gaseous fire-extinguishing systems - Physical properties and system design - Part 1: General requirements

ISO 14520-1:2015 specifies requirements and gives recommendations for the design, installation, testing, maintenance and safety of gaseous fire fighting systems in buildings, plants or other structures, and the characteristics of the various extinguishants and types of fire for which they are a suitable extinguishing medium. It covers total flooding systems primarily related to buildings, plants and other specific applications, utilizing electrically non-conducting gaseous fire extinguishants that do not leave a residue after discharge and for which there are sufficient data currently available to enable validation of performance and safety characteristics by an appropriate independent authority. This part of ISO 14520 is not applicable to explosion suppression. ISO 14520-1:2015 is not intended to indicate approval of the extinguishants listed therein by the appropriate authorities, as other extinguishants may be equally acceptable. CO2 is not included as it is covered by other International Standards.

Systèmes d'extinction d'incendie utilisant des agents gazeux — Propriétés physiques et conception des systèmes — Partie 1: Exigences générales

General Information

• Status: Withdrawn
• Publication Date: 07-Dec-2015
• ICS: 13.220.10 - Fire-fighting
• Technical Committee: ISO/TC 21/SC 8 - Gaseous media and firefighting systems using gas
• Drafting Committee: ISO/TC 21/SC 8/WG 5 - General Requirements
• Current Stage: 9599 - Withdrawal of International Standard
• Start Date: 03-Feb-2023
• Completion Date: 13-Dec-2025

Relations

• Revised: ISO 14520-1:2023 - Gaseous fire-extinguishing systems - Physical properties and system design - Part 1: General requirements
• Effective Date: 23-Apr-2020
• Revises: ISO/TS 20885:2003 - Gaseous media fire-extinguishing systems - Area coverage fire test procedure - Engineered and pre-engineered extinguishing units
• Effective Date: 18-Feb-2010
• Revises: ISO 14520-1:2006 - Gaseous fire-extinguishing systems - Physical properties and system design - Part 1: General requirements
• Effective Date: 03-Oct-2009

Standards Content (Sample)

DRAFT INTERNATIONAL STANDARD
ISO/DIS 14520-1
ISO/TC 21/SC 8 Secretariat: SA
Voting begins on: Voting terminates on:
2014-12-08 2015-03-08
Gaseous fire-extinguishing systems — Physical properties
and system design —
Part 1:
General requirements
Systèmes d’extinction d’incendie utilisant des agents gazeux — Propriétés physiques et conception des
systèmes —
Partie 1: Exigences générales
ICS: 13.220.10
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 14520-1:2014(E)
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. ISO 2014

ISO/DIS 14520-1:2014(E)
© ISO 2014
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
Web www.iso.org
Published in Switzerland
ii © ISO 2014 – All rights reserved

ISO/CD 14520-1
Contents Page
Foreword . vii
Introduction . vii
1 Scope . 1
2 Normative references . 2
3 Terms and definitions . 3
4 Use and limitations . 6
4.1 General . 6
4.2 Extinguishants . 7
4.2.1 Environmental properties . 7
4.3 Electrostatic discharge . 7
4.4 Compatibility with other extinguishants . 8
4.5 Temperature limitations . 8
5 Safety . 8
5.1 Hazard to personnel . 8
5.2 Safety precautions . 9
5.2.1 General . 9
5.2.2 For normally occupied areas . 9
5.2.3 For normally unoccupied areas . 9
5.2.4 For unoccupiable areas . 12
5.3 Occupiable areas . 12
5.4 Electrical hazards . 13
5.5 Electrical earthing . 13
5.6 Electrostatic discharge . 14
6 System design . 14
6.1 General . 14
6.2 Extinguishant supply . 14
6.2.1 Quantity . 14
6.2.2 Quality. 14
6.2.3 Container arrangement . 14
6.2.4 Storage containers . 14
6.3 Distribution . 15
6.3.1 General . 15
6.3.2 Piping . 16
6.3.3 Fittings . 16
6.3.4 Pipe and valve supports . 17
6.3.5 Valves . 17
6.3.6 Nozzles . 18
6.3.7 Pressure reducing orifice assembly . 18
6.4 Detection, actuation and control systems . 19
6.4.1 General . 19
6.4.2 Automatic detection . 19
6.4.3 Operating devices . 19
6.4.4 Control equipment . 20
6.4.5 Operating alarms and indicators . 20
6.4.6 Hold switches . 20
7 Extinguishant system design . 20
7.1 General . 20
7.2 Specifications, plans and approvals . 21
ISO/CD 14520-1
7.2.1 Specifications . 21
7.2.2 Working documents . 21
7.3 System flow calculations . 21
7.3.1 General . 21
7.3.2 Balanced and unbalanced system . 21
7.3.3 Friction losses . 24
7.3.4 Pressure drop . 24
7.3.5 Valves and fittings . 24
7.3.6 Piping length . 24
7.3.7 Drawings . 24
7.3.8 Liquefied gases — Specific requirements . 24
7.4 Enclosures . 24
7.5 Extinguishant concentration requirements . 25
7.5.1 Flame extinguishment . 25
7.5.2 Inerting . 26
7.6 Total flooding quantity . 26
7.6.1 General . 26
7.6.2 Liquefied gases . 26
7.6.3 Non-liquefied gas . 27
7.7 Altitude adjustment . 27
7.8 Duration of protection . 28
7.9 System performance . 28
7.9.1 Discharge time . 28
7.9.2 Extended discharge . 29
8 Commissioning and acceptance . 29
8.1 General . 29
8.2 Tests . 29
8.2.1 General . 29
8.2.2 Enclosure check . 29
8.2.3 Review of mechanical components . 29
8.2.4 Review of enclosure integrity . 30
8.2.5 Review of electrical components . 30
8.2.6 Preliminary functional tests . 31
8.2.7 System functional operational test . 32
8.2.8 Remote monitoring operations (if applicable) . 32
8.2.9 Control panel primary power source . 32
8.2.10 Completion of functional tests . 32
8.3 Completion certificate and documentation . 32
9 Inspection, maintenance, testing and training . 33
9.1 General . 33
9.2 Inspection . 33
9.2.1 General . 33
9.2.2 Container . 33
9.2.3 Hose . 33
9.2.4 Enclosures . 33
9.3 Maintenance . 34
9.3.1 General . 34
9.3.2 User's programme of inspection . 34
9.3.3 Service schedule. 34
9.4 Training . 34
Annex A (normative) Working documents . 35
A.1 General . 35
A.2 Working documents . 35
A.3 Specific details . 36
A.3.1 Pre-engineered systems . 36
A.3.2 Engineered systems . 36
Annex B (normative) Determination of flame-extinguishing concentration of gaseous
extinguishants by the cup burner method . 37
iv © ISO 2013 – All rights reserved

ISO/CD 14520-1
B.1 Scope . 37
B.2 Principle. 37
B.3 Requirements for apparatus. 37
B.3.1 General . 37
B.3.2 Cup . 38
B.3.3 Chimney. 38
B.3.4 Diffuser . 38
B.3.5 Fuel supply . 39
B.3.6 Manifold . 39
B.3.7 Air supply . 39
B.3.8 Extinguishant supply . 39
B.3.9 Delivery system . 39
B.4 Requirements for materials . 39
B.4.1 Air . 39
B.4.2 Fuel . 39
B.4.3 Extinguishant . 39
B.5 Procedure for inflammable liquids . 39
B.6 Procedure for inflammable gases . 40
B.7 Extinguishant extinguishing concentration . 41
B.7.1 Preferred method . 41
B.7.2 Alternative method . 41
B.8 Reporting of results . 42
Annex C (normative) Fire extinguishment/area coverage fire test procedure for engineered and
pre-engineered extinguishing units . 43
C.1 Requirements . 43
C.2 Type of test and report of test results . 43
C.2.1 Type of test . 43
C.2.2 Reporting of test results . 44
C.3 Extinguishing system . 46
C.4 Extinguishing concentration . 47
C.4.1 Extinguishing agent concentration . 47
C.4.2 Cold discharge test . 48
C.5 Nozzle distribution verification tests . 49
C.5.1 Nozzle minimum height/maximum area coverage test . 49
C.5.2 Nozzle maximum height test . 55
C.6 Extinguishing concentration tests . 57
C.6.1 Wood crib test . 57
C.6.2 Heptane pan test . 63
C.6.3 Polymeric sheet fire test . 65
Annex D (normative) Method of evaluating inerting concentration of a fire extinguishant . 71
D.1 Scope . 71
D.2 Principle. 71
D.3 Apparatus . 71
D.4 Procedure . 71
D.5 Inerting concentration . 72
Annex E (normative) Door fan test for determining of minimum hold time . 73
E.1 Scope . 73
E.2 Test for determination of predicted hold time . Error! Bookmark not defined.
E.2.1 Principle. Error! Bookmark not defined.
E.2.2 Apparatus . Error! Bookmark not defined.
E.2.3 Calibration and accuracy of apparatus . Error! Bookmark not defined.
E.2.4 Preliminary preparation . Error! Bookmark not defined.
E.2.5 Evaluation of enclosure . Error! Bookmark not defined.
E.2.6 Measurement of enclosure . Error! Bookmark not defined.
E.2.7 Test procedure . Error! Bookmark not defined.
E.2.8 Calculation . Error! Bookmark not defined.
E.3 Treatment of enclosures with predicted hold times less than the recommended valueError! Bookmark no
E.3.1 General . Error! Bookmark not defined.
ISO/CD 14520-1
E.3.2 Leakage areas . Error! Bookmark not defined.
E.3.3 Improved sealing of the enclosure . Error! Bookmark not defined.
E.3.4 Quantification and location of leaks . Error! Bookmark not defined.
E.4 Report . Error! Bookmark not defined.
Annex F (informative) System performance verification . 89
Annex G (informative) Safe personnel exposure guidelines. 90
G.1 Scope . 90
G.2 Safety . 90
G.3 Hazards to personnel — Potential hazards . 90
G.3.1 Agent itself . 90
G.3.2 Noise . 90
G.3.3 Turbulence . 90
G.3.4 Low temperature . 90
G.4 Halocarbon agents. 91
G.4.1 Toxicity of halocarbons (liquefied gases) . 91
G.4.2 PBPK model . 92
G.4.3 Safe exposure guidelines for halocarbons . 93
G.5 Inert gas (non-liquefied gas) . 95
G.5.1 Physiological effects of inert gas agents . 95
G.5.2 Safe exposure guidelines for inert gas agents . 95
Annex H (informative) Flow calculation implementation method and flow calculation verification and
testing for approvals. 97
H.1 Scope . 97
H.2 Calculation method implementation . 97
H.3 Minimum accuracy recommendations . 98
H.3.1 Recommended design limits to be included inside the flow calculation method (software) . 98
H.4 Recommended testing procedure for system flow calculation method (software)
validation . 98
H.4.1 General . 98
H.4.2 System design for testing . 99
H.5 Pass/fail criteria . 100

vi © ISO 2013 – All rights reserved

ISO/CD 14520-1
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 14520 1 was prepared by Technical Committee ISO/TC 21, Equipment for fire protection and fire fighting,
Subcommittee SC 8, Gaseous media and firefighting systems using gas.
This second edition cancels and replaces the first edition (ISO 14520-1:2000), which has been technically
revised.
Annex C has been extensively revised to include polymeric sheet fuel array fire tests [polymethyl methacrylate
(PMMA)], [polypropylene (PP)] and [acrylonitrile-butadiene-styrene (ABS)]. These tests are designed to more
closely represent plastic fuel hazards such as may be encountered in information technology,
telecommunications and process control facilities.
Annex E has been re-structured to accommodate lighter-than-air gases and to provide means for dealing with
non-standard (as opposed to geometrically regular) hazard enclosures.
Also incorporated in this revision of ISO 14520-1 are safe personnel exposure guidelines. Annex G,
recognizing physiologically based pharmacokinetic (PBPK) modelling and hypoxic guidelines to define safe
human exposure limits.
ISO 14520 consists of the following parts, under the general title Gaseous fire-extinguishing systems —
Physical properties and system design6:
— Part 1: General requirements
— Part 2: CF3I extinguishant
— Part 5: FK-5-1-12 extinguishant
— Part 6: HCFC Blend A extinguishant
— Part 8: HFC 125 extinguishant
— Part 9: HFC 227ea extinguishant
— Part 10: HFC 23 extinguishant
— Part 11: HFC 236fa extinguishant
ISO/CD 14520-1
— Part 12: IG-01 extinguishant
— Part 13: IG-100 extinguishant
— Part 14: IG-55 extinguishant
— Part 15: IG-541 extinguishant
Parts 3, 4 and 7, which dealt with FC-2-1-8, FC-3-1-10 and HCFC 124 extinguishants, respectively, have been
withdrawn, as these types are no longer manufactured.
viii © ISO 2013 – All rights reserved

ISO/CD 14520-1
Introduction
Fire fighting systems covered in this part of ISO 14520 are designed to provide a supply of gaseous
extinguishing medium for the extinction of fire.
Several different methods of supplying extinguishant to, and applying it at, the required point of discharge for
fire extinction have been developed in recent years, and there is a need for dissemination of information on
established systems and methods. This part of ISO 14520 has been prepared to meet this need.
In particular, new requirements to eliminate the need to release extinguishants during testing and
commissioning procedures are included. These are linked to the inclusion of enclosure integrity testing.
The requirements of this part of ISO 14520 are made in the light of the best technical data known to the
working group at the time of writing but, since a wide field is covered, it has been impracticable to consider
every possible factor or circumstance that might affect implementation of the recommendations.
It has been assumed in the preparation of this part of ISO 14520 that the execution of its provisions is
entrusted to people appropriately qualified and experienced in the specification, design, installation, testing,
approval, inspection, operation and maintenance of systems and equipment, for whose guidance it has been
prepared, and who can be expected to exercise a duty of care to avoid unnecessary release of extinguishant.
Attention is drawn to the Montreal Protocol on substances that deplete the ozone layer.
It is important that the fire protection of a building or plant be considered as a whole. Gaseous extinguishant
systems form only a part, though an important part, of the available facilities, but it should not be assumed that
their adoption necessarily removes the need to consider supplementary measures, such as the provision of
portable fire extinguishers or other mobile appliances for first aid or emergency use, or to deal with special
hazards.
Gaseous extinguishants have for many years been a recognized effective medium for the extinction of
inflammable liquid fires and fires in the presence of electrical and ordinary Class A hazards, but it should not
be forgotten, in the planning of comprehensive schemes, that there may be hazards for which these media are
not suitable, or that in certain circumstances or situations there may be dangers in their use requiring special
precautions.
Advice on these matters can be obtained from the appropriate manufacturer of the extinguishant or the
extinguishing system. Information may also be sought from the appropriate fire authority, the health and safety
authorities and insurers. In addition, reference should be made as necessary to other national standards and
statutory regulations of the particular country.
It is essential that fire-fighting equipment be carefully maintained to ensure instant readiness when required.
Routine maintenance is liable to be overlooked or given insufficient attention by the owner of the system. It is,
however, neglected at peril to the lives of occupants of the premises and at the risk of crippling financial loss.
The importance of maintenance cannot be too highly emphasized. Installation and maintenance should only
be done by qualified personnel.
Inspection preferably by a third party, should include an evaluation that the extinguishing system continues to
provide adequate protection for the risk (protected zones as well as state of the art can change over time).
ISO/CD 14520-1
The test protocol contained in Annex C of this part of ISO 14520 was developed by a special working group of
ISO/TC 21/SC 8. Annex C deals with the tests for determination of the extinguishing concentrations and
system performance and they are designed in such a way to allow individual installers to use his/her/system
and carry out all of the extinguishing tests. The need for the tests presented in Annex C was established by
the fact that the previously used Class A fire test involved wood crib, heptane pan and heptane can test fires
in an enclosure of 100 m , and did not necessarily indicate extinguishing concentrations suitable for the
protection of plastic fuel hazards such as may be encountered in information technology, telecommunications
and process control facilities.
As a consequence of the above, the current Annex C of this part of ISO 14520 has been revised as described
in the Foreword.
Specific parts 3, 4 and 7 have been withdrawn on the basis that the extinguishing media have not been
commercialized, and a new agent specific part 5 has been introduced to cover FK-5-1-12 (dodecafluoro-2-
methylpentan-3-one) systems.
x © ISO 2013 – All rights reserved

COMMITTEE DRAFT ISO/CD 14520-1

Physical properties and system design - Part 1: General
requirements
1 Scope
This part of ISO 14520 specifies requirements and gives recommendations for the design, installation, testing,
maintenance and safety of gaseous fire fighting systems in buildings, plant or other structures, and the
characteristics of the various extinguishants and types of fire for which they are a suitable extinguishing
medium.
It covers total flooding systems primarily related to buildings, plant and other specific applications, utilizing
electrically non-conducting gaseous fire extinguishants that do not leave a residue after discharge and for
which there are sufficient data currently available to enable validation of performance and safety
characteristics by an appropriate independent authority. This part of ISO 14520 is not applicable to explosion
suppression.
This part of ISO 14520 is not intended to indicate approval of the extinguishants listed therein by the
appropriate authorities, as other extinguishants may be equally acceptable. CO is not included as it is
covered by other International Standards.
This part of ISO 14520 is applicable to the extinguishants listed in Table 1. It is essential that it be used in
conjunction with the separate parts of ISO 14520 for specific extinguishants, as cited in Table 1.
ISO/CD 14520-1
Table 1 — Listed extinguishant
Extinguishant Chemical Formula CAS No. International
Standard
CF l Trifluoroiodomethane CF l 2314-97-8 ISO 14520-2
3 3
FK-5-1-12 Dodecafluoro-2- CF CF C(O)CF(CF ) 756-13-8 ISO 14520-5
3 2 3 2
methylpentan-3-one
HCFC Blend A
HCFC-123 Dichlorotrifluoroethane CHCl CF 306-83-2
2 3
HCFC-22 Chlorodifluoromethane CHClF 75-45-6 ISO 14520-6
HCFC-124 Chlorotetrafluoroethane CFClFCF 2837-89-0
Isopropenyl-1- C H 5989-27-5
10 16
methylcyclohexene
HFC 125 Pentafluoroethane CHF CF 354-33-6 ISO 14520-8
2 3
HFC 227ea Heptafluoropropane CF CHFCF 2252-84-8 ISO 14520-9
3 3
HFC 23 Trifluoromethane CHF 75-46-7 ISO 14520-10
HFC 236fa Hexafluoropropane CF CH CF 27070-61-7 ISO 14520-11
3 2 3
IG-01 Argon Ar 74040-37-1 ISO 14520-12
IG-100 Nitrogen N 7727-37-9 ISO 14520-13
Nitrogen (50 %) N 7727-37-9
IG-55 Argon (50 %) Ar 74040-37-1 ISO 14520-14
Nitrogen (52 %) N 7727-37-9
IG-541 Argon (40 %) Ar 74040-37-1 ISO 14520-15
Carbon dioxide (8 %) CO2 124-38-9
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 3941, Classification of fires
ISO 5660-1, Reaction-to-fire tests — Heat release, smoke production and mass loss rate — Part 1: Heat
release rate (cone calorimeter method)
ISO 14520-2, Gaseous fire-extinguishing systems — Physical properties and system design — Part 2: CF I
extinguishant
ISO 14520-5, Gaseous fire-extinguishing systems — Physical properties and system design — Part 5: FK-5-
1-12 extinguishant
ISO 14520-6, Gaseous fire-extinguishing systems — Physical properties and system design — Part 6: HCFC
Blend A extinguishant
2 © ISO 2013 – All rights reserved

ISO/CD 14520-1
ISO 14520-8, Gaseous fire-extinguishing systems — Physical properties and system design — Part 8:
HFC 125 extinguishant
ISO 14520-9, Gaseous fire-extinguishing systems — Physical properties and system design — Part 9:
HFC 227ea extinguishant
ISO 14520-10, Gaseous fire-extinguishing systems — Physical properties and system design — Part 10:
HFC 23 extinguishant
ISO 14520-11, Gaseous fire-extinguishing systems — Physical properties and system design — Part 11:
HFC 236fa extinguishant
ISO 14520-12, Gaseous fire-extinguishing systems — Physical properties and system design — Part 12: IG-
01 extinguishant
ISO 14520-13, Gaseous fire-extinguishing systems — Physical properties and system design — Part 13: IG-
100 extinguishant
ISO 14520-14, Gaseous fire-extinguishing systems — Physical properties and system design — Part 14: IG-
55 extinguishant
ISO 14520-15, Gaseous fire-extinguishing systems — Physical properties and system design — Part 15: IG-
541 extinguishant
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
NOTE For the purposes of this document, the term “bar” shall be taken as “gauge”, unless otherwise indicated.
Concentrations or quantities expressed in percentages (%) shall be taken as by volume, unless otherwise indicated.
3.1
approved
acceptable to a relevant authority (see 3.2)
NOTE In determining the acceptability of installations or procedures, equipment or materials, the authority can base
acceptance on compliance with the appropriate standards.
3.2
authority
organization, office or individual responsible for approving equipment, installations or
...

INTERNATIONAL ISO
STANDARD 14520-1
Third edition
2015-12-01
Corrected version
2016-04-01
Gaseous fire-extinguishing systems —
Physical properties and system
design —
Part 1:
General requirements
Systèmes d’extinction d’incendie utilisant des agents gazeux —
Propriétés physiques et conception des systèmes —
Partie 1: Exigences générales
Reference number
©
ISO 2015
© ISO 2015, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. [phone]
Fax [phone]
[e-mail]
www.iso.org
ii © ISO 2015 – All rights reserved

Contents Page
Foreword .vi
Introduction .viii
1 Scope . 1
2 Normative references . 2
3 Terms and definitions . 2
4 Use and limitations . 6
4.1 General . 6
4.2 Extinguishants . 6
4.2.1 Environmental properties . 7
4.3 Electrostatic discharge . 7
4.4 Compatibility with other extinguishants . 7
4.5 Temperature limitations . 7
5 Safety . 7
5.1 Hazard to personnel . 7
5.2 Safety precautions . 8
5.2.1 General. 8
5.2.2 For normally occupied areas . 8
5.2.3 For normally unoccupied areas.10
5.2.4 For unoccupiable areas .10
5.3 Occupiable areas .10
5.4 Electrical hazards .11
5.5 Electrical earthing .11
5.6 Electrostatic discharge .11
6 System design .12
6.1 General .12
6.2 Extinguishant supply .12
6.2.1 Quantity .12
6.2.2 Quality .12
6.2.3 Container arrangement .12
6.2.4 Storage containers .12
6.3 Distribution .13
6.3.1 General.13
6.3.2 Piping .14
6.3.3 Fittings .14
6.3.4 Pipe and valve supports .15
6.3.5 Valves .16
6.3.6 Nozzles .16
6.3.7 Pressure reducing orifice assembly.17
6.4 Detection, actuation and control systems.17
6.4.1 General.17
6.4.2 Automatic detection .17
6.4.3 Operating devices .17
6.4.4 Control equipment .18
6.4.5 Operating alarms and indicators .18
6.4.6 Hold switches.18
7 Extinguishant system design .18
7.1 General .18
7.2 Specifications, plans and approvals .19
7.2.1 Specifications .19
7.2.2 Working documents .19
7.3 System flow calculations .19
7.3.1 General.19
7.3.2 Balanced and unbalanced system .19
7.3.3 Friction losses.21
7.3.4 Pressure drop .21
7.3.5 Valves and fittings .21
7.3.6 Piping length .22
7.3.7 Drawings .22
7.3.8 Liquefied gases — Specific requirements .22
7.4 Enclosures .22
7.5 Extinguishant concentration requirements .22
7.5.1 Flame extinguishment . .22
7.5.2 Inerting .24
7.6 Total flooding quantity .24
7.6.1 General.24
7.6.2 Liquefied gases .24
7.6.3 Non-liquefied gas . .24
7.7 Altitude adjustment .25
7.8 Duration of protection .25
7.9 System performance .26
7.9.1 Discharge time .26
7.9.2 Extended discharge .26
8 Commissioning and acceptance .26
8.1 General .26
8.2 Tests .26
8.2.1 General.26
8.2.2 Enclosure check .27
8.2.3 Review of mechanical components .27
8.2.4 Review of enclosure integrity .28
8.2.5 Review of electrical components .28
8.2.6 Preliminary functional tests . .29
8.2.7 System functional operational test.29
8.2.8 Remote monitoring operations (if applicable) .30
8.2.9 Control panel primary power source .30
8.2.10 Completion of functional tests .30
8.3 Completion certificate and documentation.30
9 Inspection, maintenance, testing and training.30
9.1 General .30
9.2 Inspection .31
9.2.1 General.31
9.2.2 Container .31
9.2.3 Hose .31
9.2.4 Enclosures .31
9.3 Maintenance .32
9.3.1 General.32
9.3.2 User’s programme of inspection .32
9.3.3 Service schedule .32
9.4 Training .32
Annex A (normative) Working documents .33
Annex B (normative) Determination of flame-extinguishing concentration of gaseous
extinguishants by the cup burner method .35
Annex C (normative) Fire extinguishment/area coverage fire test procedure for engineered
and pre-engineered extinguishing units .41
Annex D (normative) Method of evaluating inerting concentration of a fire extinguishant .70
Annex E (normative) Door fan test for determining of minimum hold time .72
Annex F (informative) System performance verification .88
iv © ISO 2015 – All rights reserved

Annex G (informative) Safe personnel exposure guidelines .89
Annex H (informative) Flow calculation implementation method and flow calculation
verification and testing for approvals .96
Bibliography .100
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 WTO principles in the Technical
Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 21, Equipment for fire protection and fire fighting,
Subcommittee SC 8, Gaseous media and firefighting systems using gas.
This third edition cancels and replaces the second edition (ISO 14520-1:2006), which has been
technically revised. It also incorporates ISO 14520-1:2006/Cor 1:2007 and ISO/TS 20885:2003.
This corrected version of ISO 14520-1:2015 incorporates the following corrections.
Foreword: the details of documents that ISO 14520-1:2015 cancels and replaces have been amended.
7.6.3: the numerator within brackets in Formula 4 has been corrected (from C to 100).
C.4.1: the numerator within brackets in Formula C.2 has been corrected (from C to 100).
The most important changes in the third edition are as follows.
Methods are given to calculate the effects of atmospheric pressure on the inert gases.
The discharge time for inert gas agents has been increased from a maximum of 60 seconds to a
maximum of 120 seconds for the protection of Class A hazards.
The height at which agent concentrations are to be held following a discharge, and during the hold time,
has been revised to reflect the height of the protected hazard replacing the previous requirement of
10%, 50% and 90% of the enclosure height.
Annexes B, C and E have been modified to reflect experience gained in the areas covered by these
Annexes, since the last edition.
Annex H has been amended to reflect the content of what was previously ISO/TS 13075.
Certain environmental data has been added in the specific agents parts of ISO 14520 and an explanation
and advice on where additional information can be found has been added as Clause 4.2.1.
ISO 14520 consists of the following parts, under the general title Gaseous fire-extinguishing systems —
Physical properties and system design
vi © ISO 2015 – All rights reserved

— Part 1: General requirements
— Part 2: CF3I extinguishant
— Part 5: FK-5-1-12 extinguishant
— Part 6: HCFC Blend A extinguishant
— Part 8: HFC 125 extinguishant
— Part 9: HFC 227ea extinguishant
— Part 10: HFC 23 extinguishant
— Part 11: HFC 236fa extinguishant
— Part 12: IG-01 extinguishant
— Part 13: IG-100 extinguishant
— Part 14: IG-55 extinguishant
— Part 15: IG-541 extinguishant
Introduction
Fire fighting systems covered in this part of ISO 14520 are designed to provide a supply of gaseous
extinguishing medium for the extinction of fire.
Several different methods of supplying extinguishant to, and applying it at, the required point of
discharge for fire extinction have been developed in recent years, and there is a need for dissemination
of information on established systems and methods. This part of ISO 14520 has been prepared to meet
this need.
The requirements of this part of ISO 14520 are made in the light of the best technical data known to
the working group at the time of writing but, since a wide field is covered, it has been impracticable
to consider every possible factor or circumstance that might affect implementation of the
recommendations.
It has been assumed in the preparation of this part of ISO 14520 that the execution of its provisions is
entrusted to people appropriately qualified and experienced in the specification, design, installation,
testing, approval, inspection, operation and maintenance of systems and equipment, for whose guidance
it has been prepared, and who can be expected to exercise a duty of care to avoid unnecessary release
of extinguishant.
Attention is drawn to the Montreal Protocol on substances that deplete the ozone layer.
It is important that the fire protection of a building or plant be considered as a whole. Gaseous
extinguishant systems form only a part, though an important part, of the available facilities, but it
should not be assumed that their adoption necessarily removes the need to consider supplementary
measures, such as the provision of portable fire extinguishers or other mobile appliances for first aid or
emergency use, or to deal with special hazards.
Gaseous extinguishants have for many years been a recognized effective medium for the extinction
of inflammable liquid fires and fires in the presence of electrical and ordinary Class A hazards, but
it should not be forgotten, in the planning of comprehensive schemes, that there may be hazards for
which these media are not suitable, or that in certain circumstances or situations there may be dangers
in their use requiring special precautions.
Advice on these matters can be obtained from the appropriate manufacturer of the extinguishant or
the extinguishing system. Information may also be sought from the appropriate fire authority, the
health and safety authorities and insurers. In addition, reference should be made as necessary to other
national standards and statutory regulations of the particular country.
It is essential that fire-fighting equipment be carefully maintained to ensure instant readiness when
required. Routine maintenance is liable to be overlooked or given insufficient attention by the owner of
the system. It is, however, neglected at peril to the lives of occupants of the premises and at the risk of
crippling financial loss. The importance of maintenance cannot be too highly emphasized. Installation
and maintenance should only be done by qualified personnel.
Inspection preferably by a third party, should include an evaluation that the extinguishing system
continues to provide adequate protection for the risk (protected zones, as well as state of the art can
change over time).
viii © ISO 2015 – All rights reserved

INTERNATIONAL STANDARD ISO 14520-1:2015(E)
Gaseous fire-extinguishing systems — Physical properties
and system design —
Part 1:
General requirements
1 Scope
This part of ISO 14520 specifies requirements and gives recommendations for the design, installation,
testing, maintenance and safety of gaseous fire fighting systems in buildings, plants or other structures,
and the characteristics of the various extinguishants and types of fire for which they are a suitable
extinguishing medium.
It covers total flooding systems primarily related to buildings, plants and other specific applications,
utilizing electrically non-conducting gaseous fire extinguishants that do not leave a residue after
discharge and for which there are sufficient data currently available to enable validation of performance
and safety characteristics by an appropriate independent authority. This part of ISO 14520 is not
applicable to explosion suppression.
This part of ISO 14520 is not intended to indicate approval of the extinguishants listed therein by the
appropriate authorities, as other extinguishants may be equally acceptable. CO is not included as it is
covered by other International Standards.
This part of ISO 14520 is applicable to the extinguishants listed in Table 1. It is essential that it be used
in conjunction with the separate parts of ISO 14520 for specific extinguishants, as cited in Table 1.
Table 1 — Listed extinguishant
Extinguishant Chemical Formula CAS No. International
Standard
CF l Trifluoroiodomethane CF l 2314-97-8 ISO 14520-2
3 3
FK-5-1-12 Dodecaf luoro-2-meth- CF CF C(O)CF(CF ) 756-13-8 ISO 14520-5
3 2 3 2
ylpentan-3-one
HCFC Blend A
HCFC-123 Dichlorotrifluoroethane CHCl CF 306-83-2
2 3
HCFC-22 Chlorodifluoromethane CHClF 75-45-6 ISO 14520-6
HCFC-124 Chlorotetrafluoroethane CFClFCF 2837-89-0
Isopropenyl-1-methylcy- C H 5989-27-5
10 16
clohexene
HFC 125 Pentafluoroethane CHF CF 354-33-6 ISO 14520-8
2 3
HFC 227ea Heptafluoropropane CF CHFCF 2252-84-8 ISO 14520-9
3 3
HFC 23 Trifluoromethane CHF 75-46-7 ISO 14520-10
HFC 236fa Hexafluoropropane CF CH CF 27070-61-7 ISO 14520-11
3 2 3
IG-01 Argon Ar 74040-37-1 ISO 14520-12
IG-100 Nitrogen N 7727-37-9 ISO 14520-13
Nitrogen (50 %) N 7727-37-9
IG-55 Argon (50 %) Ar 74040-37-1 ISO 14520-14
Table 1 (continued)
Extinguishant Chemical Formula CAS No. International
Standard
Nitrogen (52 %) N 7727-37-9
IG-541 Argon (40 %) Ar 74040-37-1 ISO 14520-15
Carbon dioxide (8 %) CO2 124-38-9
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 14520-2, Gaseous fire-extinguishing systems — Physical properties and system design — Part 2: CF3I
extinguishant
ISO 14520-5, Gaseous fire-extinguishing systems — Physical properties and system design — Part 5: FK-5-
1-12 extinguishant
ISO 14520-6, Gaseous fire-extinguishing systems — Physical properties and system design — Part 6: HCFC
Blend A extinguishant
ISO 14520-8, Gaseous fire-extinguishing systems — Physical properties and system design —
Part 8: HFC 125 extinguishant
ISO 14520-9, Gaseous fire-extinguishing systems — Physical properties and system design —
Part 9: HFC 227ea extinguishant
ISO 14520-10, Gaseous fire-extinguishing systems — Physical properties and system design —
Part 10: HFC 23 extinguishant
ISO 14520-11, Gaseous fire-extinguishing systems — Physical properties and system design —
Part 11: HFC 236fa extinguishant
ISO 14520-12, Gaseous fire-extinguishing systems — Physical properties and system design — Part 12: IG-
01 extinguishant
ISO 14520-13, Gaseous fire-extinguishing systems — Physical properties and system design — Part 13: IG-
100 extinguishant
ISO 14520-15, Gaseous fire-extinguishing systems — Physical properties and system design — Part 15: IG-
541 extinguishant
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
NOTE For the purposes of this document, the term “bar” shall be taken as “gauge”, unless otherwise
indicated. Concentrations or quantities expressed in percentages (%) shall be taken as by volume, unless
otherwise indicated.
3.1
approved
acceptable to a relevant authority
Note 1 to entry: See 3.2.
2 © ISO 2015 – All rights reserved

Note 2 to entry: In determining the acceptability of installations or procedures, equipment, or materials, the
authority can base acceptance on compliance with the appropriate International Standards.
3.2
authority
organization, office, or individual responsible for approving equipment, installations, or procedures
3.3
automatic/manual switch
means of converting the system from automatic to manual actuation
Note 1 to entry: This can be in the form of a manual switch on the control panel or other units, or a personnel
door interlock. In all cases, this changes the actuation mode of the system from automatic and manual to manual
only or vice versa.
3.4
extinguishant
electrically non-conducting gaseous fire extinguishing agent that, upon evaporation, does not leave
a residue
Note 1 to entry: See Table 1.
Note 2 to entry: The terms “extinguishant” and “agent” are used interchangeably throughout in this part of
ISO 14520.
3.5
clearance
air gap between equipment, including piping and nozzles and unenclosed or uninsulated live electrical
components at other than ground potential
3.6
concentration
3.6.1
design concentration
concentration of extinguishant, including a safety factor, required for system design purposes
3.6.2
maximum concentration
concentration achieved from the actual extinguishant quantity at the maximum ambient temperature
in the protected area
3.6.3
extinguishing concentration
minimum concentration of extinguishant required to extinguish a fire involving a particular fuel under
defined experimental conditions excluding any safety factor
3.7
engineered system
system in which the supply of extinguishant stored centrally is discharged through a system of pipes
and nozzles in which the size of each section of pipe and nozzle orifice has been calculated in accordance
with relevant parts of ISO 14520
3.8
fill density
mass of extinguishant per unit volume of container
3.9
flooding quantity
mass or volume of extinguishant required to achieve the design concentration within the protected
volume
3.10
nett volume
volume enclosed by the building elements around the protected enclosure, minus the volume of any
permanent impermeable building elements within the enclosure
3.11
hold time
period of time during which a concentration of extinguishant greater than the fire extinguishing
concentration surrounds the hazard
3.12
inspection
visual check to give reasonable assurance that the extinguishing system is fully charged and operable
Note 1 to entry: This is done by seeing that the system is in place, that it has not been activated or tampered with,
and that there is no obvious physical damage or condition to prevent operation.
3.13
liquefied gas
gas or gas mixture (normally a halocarbon), which is liquid at the container pressurization level at room
temperature (20 °C)
3.14
lock-off device
manual shut-off valve installed in the discharge piping downstream of the agent containers or another
type of device that mechanically prevents agent container actuation
Note 1 to entry: The actuation of this device provides an indication of system isolation.
Note 2 to entry: The intent is to prevent the discharge of agent into the hazard area when the lock-off device is
activated.
3.15
lowest observed adverse effect level
LOAEL
lowest concentration at which an adverse toxicological or physiological effect has been observed
3.16
maintenance
thorough check, comprising a thorough examination and any necessary repair or replacement of system
component, to give maximum assurance that the extinguishing system will operate as intended
3.17
maximum working pressure
equilibrium pressure within a container at the maximum working temperature
Note 1 to entry: For liquefied gases, this is at the maximum fill density and can include superpressurization.
Note 2 to entry: The equilibrium pressure for a container in transit can differ from that in storage within a
building.
3.18
no observed adverse effect level
NOAEL
highest concentration at which no adverse toxicological or physiological effect has been observed
3.19
non-liquefied gas
gas or gas mixture (normally an inert gas), which, under service pressure and permissible service
temperature conditions, is always present in the gaseous form
4 © ISO 2015 – All rights reserved

3.20
normally occupied area
area intended for occupancy
3.21
normally unoccupied area
area not normally occupied by people but which may be entered occasionally for brief periods
3.22
pre-engineered systems
system consisting of a supply of extinguishant of specified capacity coupled to pipework with a balanced
nozzle arrangement up to a maximum permitted design
Note 1 to entry: No deviation is permitted from the limits specified by the manufacturer or authority.
3.23
regulated system
non-liquefied gas system where the pressure downstream of a pressure regulation device is limited to
some maximum pressure under both flow and no flow conditions
3.24
safety factor
multiplier of the agent extinguishing concentration to determine the agent minimum design
concentration
3.25
sea level equivalent of agent
agent concentration (volume percent) at sea level for which the partial pressure of agent matches the
ambient partial pressure of agent at a given altitude
3.26
sea level equivalent of oxygen
oxygen concentration (volume percent) at sea level for which the partial pressure of oxygen matches
the ambient partial pressure of oxygen at a given altitude
3.27
selector valve
valve installed in the discharge piping downstream of the agent containers, to direct the agent to the
appropriate hazard enclosure
Note 1 to entry: It is used where one or more agent containers are arranged in order to selectively discharge
agent to any of several separate hazard enclosures.
3.28
superpressurization
addition of a gas to the extinguishant container, where necessary, to achieve the required pressure for
proper system operation
3.29
total flooding system
system arranged to discharge extinguishant into an enclosed space to achieve the appropriate design
concentration
3.30
unoccupiable area
area that cannot be occupied due to dimensional or other physical constraints
EXAMPLE Shallow voids and cabinets.
4 Use and limitations
4.1 General
Throughout this part of ISO 14520, the word “shall” indicates a mandatory requirement; the word
“should” indicates a recommendation or that which is advised but not required.
The design, installation, service and maintenance of gaseous fire-extinguishing systems shall be
performed by those competent in fire extinguishing system technology. Maintenance and installation
shall only be done by qualified personnel and companies.
The hazards against which these systems offer protection, and any limitations on their use, shall be
contained in the system supplier’s design manual.
Total flooding fire-extinguishing systems are used primarily for protection against hazards that are in
enclosures or equipment that, in itself, includes an enclosure to contain the extinguishant. The following
are typical of such hazards, but the list is not exhaustive:
a) electrical and electronic hazards;
b) telecommunications facilities;
c) inflammable and combustible liquids and gases;
d) other high-value assets.
4.2 Extinguishants
Any agent that is to be recognized by this part of ISO 14520 or proposed for inclusion in this part of
ISO 14520 shall first be evaluated in a manner equivalent to the process used by the U.S. Environmental
Protection Agency’s (EPA) SNAP Programme or other internationally recognized extinguishing agent
approval institutions.
The extinguishants referred to in this part of ISO 14520 are electrically non-conductive media.
The extinguishants and specialized system parameters are each covered individually in the parts
of ISO 14520 for specific extinguishants. These parts shall be used in conjunction with this part of
ISO 14520.
Unless relevant testing has been carried out to the satisfaction of the authority, the extinguishants
referred to in the specific parts of ISO 14520 shall not be used on fires involving the following:
a) chemicals containing their own supply of oxygen, such as cellulose nitrate;
b) mixtures containing oxidizing materials, such as sodium chlorate or sodium nitrate;
c) chemicals capable of undergoing autothermal decomposition, such as some organic peroxides;
d) reactive metals (such as sodium, potassium, magnesium, titanium and zirconium), reactive
hydrides, or metal amides, some of which may react violently with some gaseous extinguishants;
e) environments where significant surface areas exist at temperatures greater than the breakdown
temperature of the extinguishing agent and are heated by means other than the fire.
6 © ISO 2015 – All rights reserved

4.2.1 Environmental properties
Global warming potential (GWP) and ozone depletion potential (ODP) values applicable to the gaseous
extinguishing agents are detailed in ISO 14520-2 to ISO 14520-15.
NOTE GWP is a measure of how much a given mass of gas is estimated to contribute to global warming. The
scale is a relative comparison on a mass basis where a clean agent is compared to carbon dioxide, which has a
GWP equal to 1. ODP provides a relative comparison of the ability to react with ozone at altitudes within the
stratosphere. ODP values are reported relative to the same mass of CFC-11, which has an ODP equal to 1. The
intergovernmental panel on climate change (IPCC) and the Parties to the Montreal Protocol provide up to date
environmental information on clean agent alternatives. Users of this part of ISO 14520 are encouraged to review
the information provided by those organizations to understand the significance of the environmental properties
of the agents in this part of ISO 14520.
The list of of compounds and their global warming potentials can be found at the IPCC site at: http://
www.ipcc.ch/publications_and_data/ar4/wg1/en/ch2s2-10-2.html. The list of compounds and their
ozone depletion potentials can be found at the Montreal Protocol site at: http://montreal-protocol.
org/new_site/en/Treaties/treaties_decisions-hb.php?art_id=59,60,61,62,63.
4.3 Electrostatic discharge
Care shall be taken when discharging extinguishant into potentially explosive atmospheres. Electrostatic
charging of conductors not bonded to earth may occur during the discharge of ext
...