EN ISO 16852:2010

Flame arresters - Performance requirements, test methods and limits for use (ISO 16852:2008, including Cor 1:2008 and Cor 2:2009)

ISO 16852:2008 specifies the requirements for flame arresters that prevent flame transmission when explosive gas-air or vapour-air mixtures are present. It establishes uniform principles for the classification, basic construction and information for use, including the marking of flame arresters, and specifies test methods to verify the safety requirements and determine safe limits of use.
ISO 16852:2008 is valid for pressures ranging from 80 kPa to 160 kPa and temperatures ranging from -20 °C to +150 °C.
ISO 16852:2008 is not applicable to the following:
external safety-related measurement and control equipment that might be required to keep the operational conditions within the established safe limits;
flame arresters used for explosive mixtures of vapours and gases, which tend to self-decompose (e.g. acetylene) or which are chemically unstable;
flame arresters used for carbon disulphide, due to its special properties;
flame arresters whose intended use is for mixtures other than gas-air or vapour-air mixtures (e.g. higher oxygen-nitrogen ratio, chlorine as oxidant, etc.);
flame arrester test procedures for internal-combustion compression ignition engines;
fast acting valves, extinguishing systems and other explosion isolating systems;
flame arresters integrated or combined with explosion-protected equipment, such as blowers, fans, compressors and pumps.

Flammendurchschlagsicherungen - Leistungsanforderungen, Prüfverfahren und Einsatzgrenzen (ISO 16852:2008, einschließlich Cor 1:2008 und Cor 2:2009)

Diese Internationale Norm legt die Anforderungen an Flammendurchschlagsicherungen fest, die Flammen-durchschläge bei Vorhandensein von explosionsfähigen Gas-Luft- oder Dampf-Luft-Gemischen verhindern. Sie stellt einheitliche Grundsätze für die Klassifizierung, die grundlegende Konstruktion und die Informationen für den Einsatz einschließlich der Kennzeichnung von Flammendurchschlagsicherungen auf und legt Prüfverfahren zur Über¬prüfung der Sicherheitsanforderungen und zur Bestimmung der sicheren Einsatzgrenzen fest.
Diese Internationale Norm gilt für Drücke von 80 kPa bis 160 kPa und für Temperaturen von 20 °C bis 150 °C.
ANMERKUNG 1   Diese Internationale Norm kann für Betriebsbedingungen, die von den oben festgelegten abweichen, als Leitlinie für die Auslegung und Prüfung von Flammendurchschlag¬sicherungen, dienen. Zusätzliche Prüfungen, insbesondere hinsichtlich der vorgesehenen Einsatzbedingungen, sind jedoch ratsam. Dies ist besonders bei hohen Temperaturen und Drücken wichtig. Die Prüfgemische müssen in diesen Fällen möglicherweise verändert werden.
Diese Internationale Norm gilt nicht für:
-   externe sicherheitsrelevante Mess- und Überwachungseinrichtungen, die erforderlich sind, um die Betriebsbedingungen innerhalb der festgelegten sicheren Grenzen zu halten;
ANMERKUNG 2   Eingebaute Mess- und Überwachungseinrichtungen, wie z. B. integrierte Temperatur- und Flammen¬messfühler sowie Bauteile bei denen es beispielsweise beabsichtigt ist, dass sie schmelzen (Rückhaltestift), wegbrennen (Wetterhauben) oder sich verformen (Bimetallstreifen), fallen in den Anwendungsbereich dieser Internationalen Norm.
-   Flammendurchschlagsicherungen für explosionsfähige Gemische aus Dämpfen und Gasen, die zum Selbstzerfall neigen (z. B. Acetylen) oder die chemisch instabil sind;
-   Flammendurchschlagsicherungen, die bei Schwefelkohlenstoff eingesetzt werden, da dieser spezielle Eigenschaften besitzt;

Arrête-flammes - Exigences de performance, méthodes d'essai et limites d'utilisation (ISO 16852:2008, Cor 1:2008 et Cor 2:2009 inclus)

L'ISO 16852:2008 spécifie les exigences applicables aux arrête-flammes qui préviennent la transmission d'une flamme en présence de mélanges explosifs gaz-air ou vapeur-air. Elle établit des principes homogènes pour la classification, la construction de base et les informations pour l'utilisation, y compris le marquage des arrête-flammes et spécifie des méthodes d'essai permettant de vérifier les exigences de sécurité et de déterminer des limites de sécurité d'utilisation.
L'ISO 16852:2008 est valide pour des pressions comprises entre 80 kPa et 160 kPa et des températures comprises entre -20 °C et +150 °C.
L'ISO 16852:2008 n'est pas applicable aux cas suivants:
appareils externes de mesurage et de commande liés à la sécurité qui peuvent être nécessaires pour maintenir les conditions opérationnelles dans les limites de sécurité établies;
arrête-flammes utilisés pour des mélanges explosifs de vapeurs et de gaz qui ont tendance à s'autodécomposer (par exemple l'acétylène) ou qui sont chimiquement instables;
arrête-flammes utilisés pour le disulfure de carbone, du fait de ses propriétés spécifiques;
arrête-flammes destinés à être utilisés pour des mélanges autres que des mélanges gaz-air ou vapeur-air (par exemple avec un rapport oxygène-azote plus élevé, avec du chlore en tant qu'oxydant, etc.);
modes opératoires d'essai des arrête-flammes pour les moteurs à combustion interne et à allumage par compression;
soupapes à action rapide, systèmes de coincement et autres systèmes d'isolement d'explosion;
arrête-flammes intégrés ou combinés à des équipements dotés de protections contre les explosions, par exemple soufflantes, ventilateurs, compresseurs et pompes.

Plamenske zapore - Zahtevane lastnosti, preskusne metode in omejitve uporabe (ISO 16852:2008, vključno s Cor 1:2008 in Cor 2:2009)

Ta mednarodni standard določa zahteve za plamenske zapore, ki preprečujejo prenos plamena, kadar so prisotne eksplozivne mešanice zraka in plina ali hlapov in zraka. Vzpostavlja enotna načela za klasifikacijo, osnovno sestavo in informacije za uporabi, vključno z označevanjem plamenskih zapor, ter opredeljuje preskusne metode za izpolnjevanje varnostnih zahtev in za določevanje varnih omejitev uporabe. Ta mednarodni standard je veljaven za trak v razponu od 80 do 160 kPa in za temperature v razponu od 20 do 150°C. Ta mednarodni standard ne velja za: - zunanjo, z varnostjo povezano meritvijo in nadzor opreme, ki se lahko zahteva za ohranjanje pogojev delovanja v okviru vzpostavljenih omejitev; - plamenske zapore, ki se uporabljajo za eksplozivne mešanice hlapov in plinov, za katere je značilna samorazgraditev (npr. acetilen) ali ki so kemično nestabilne: plamenske zapore, ki se uporabljajo za ogljikov disulfid, in sicer zaradi njegovih posebnih značilnosti; - plamenske zapore, katerih predvidena uporaba je za mešanice, ki niso mešanice plina in zraka ali hlapov in zraka (npr. višje razmerje med kisikom in dušikom, klor kot oksidant, itd.); - preskusne postopke za plamenske zapore za motorje z notranjim izgorevanjem in kompresijskim vžigom; - hitro delujoče ventile, gasilne sisteme in druge sisteme za izolacijo eksplozij; - plamenske zapore, integrirane v in kombinirane z opremo za zaščito pred eksplozijami, kot so pihalniki, ventilatorji, kompresorji in črpalke.

General Information

• Status: Withdrawn
• Publication Date: 27-Apr-2010
• Withdrawal Date: 13-Apr-2025
• ICS: 13.220.10 - Fire-fighting
• ICS: 13.230 - Explosion protection
• Technical Committee: CEN/TC 305 - Potentially explosive atmospheres - Explosion prevention and protection
• Drafting Committee: CEN/TC 305 - Potentially explosive atmospheres - Explosion prevention and protection
• Current Stage: 9960 - Withdrawal effective - Withdrawal
• Start Date: 23-Nov-2016
• Completion Date: 14-Apr-2025
• Directive: 2014/34/EU - Directive 2014/34/EU Of The European Parliament And Of The Council of 26 February 2014 on the harmonisation of the laws of the Member States relating to equipment and protective systems intended for use in potentially explosive atmospheres (recast)
• Directive: 94/9/EC - Directive 94/9/EC of the European Parliament and the Council of 23 March 1994 on the approximation of the laws of the Member States concerning equipment and protective systems intended for use in potentially explosive atmospheres
• Ref Project: SIST EN ISO 16852:2010 - Flame arresters - Performance requirements, test methods and limits for use (ISO 16852:2008, including Cor 1:2008 and Cor 2:2009)

Relations

• Replaces: EN 12874:2001 - Flame arresters - Performance requirements, test methods and limits for use
• Effective Date: 22-Dec-2008
• Replaced By: EN ISO 16852:2016 - Flame arresters - Performance requirements, test methods and limits for use (ISO 16852:2016)
• Effective Date: 20-Jun-2012

Standards Content (Sample)

SLOVENSKI STANDARD
01-november-2010
1DGRPHãþD
SIST EN 12874:2002
3ODPHQVNH]DSRUH=DKWHYDQHODVWQRVWLSUHVNXVQHPHWRGHLQRPHMLWYHXSRUDEH
,62YNOMXþQRV&RULQ&RU
Flame arresters - Performance requirements, test methods and limits for use (ISO
16852:2008, including Cor 1:2008 and Cor 2:2009)
Flammendurchschlagsicherungen - Leistungsanforderungen, Prüfverfahren und
Einsatzgrenzen (ISO 16852:2008, einschließlich Cor 1:2008 und Cor 2:2009)
Arrête-flammes - Exigences de performance, méthodes d'essai et limites d'utilisation
(ISO 16852:2008, Cor 1:2008 et Cor 2:2009 inclus)
Ta slovenski standard je istoveten z: EN ISO 16852:2010
ICS:
13.220.10 Gašenje požara Fire-fighting
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 16852
NORME EUROPÉENNE
EUROPÄISCHE NORM
April 2010
ICS 13.220.10 Supersedes EN 12874:2001
English Version
Flame arresters - Performance requirements, test methods and
limits for use (ISO 16852:2008, including Cor 1:2008 and Cor
2:2009)
Arrête-flammes - Exigences de performance, méthodes Flammendurchschlagsicherungen -
d'essai et limites d'utilisation (ISO 16852:2008, Cor 1:2008 Leistungsanforderungen, Prüfverfahren und Einsatzgrenzen
et Cor 2:2009 inclus) (ISO 16852:2008, einschließlich Cor 1:2008 und Cor
2:2009)
This European Standard was approved by CEN on 16 April 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 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 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 16852:2010: E
worldwide for CEN national Members.

Contents Page
Foreword .3
Annex ZA (informative) Relationship between this European Standard and the Essential
Requirements of EU Directive 94/9/EC concerning equipment and protective systems for
use in potentially explosive atmospheres .6

Foreword
The text of ISO 16852:2008, including Cor 1:2008 and Cor 2:2009 has been prepared by Technical
Committee ISO/TC 21 “Equipment for fire protection and fire fighting” of the International Organization for
Standardization (ISO) and has been taken over as EN ISO 16852:2010 by Technical Committee CEN/TC 305
“Potentially explosive atmospheres - Explosion prevention and protection” 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 October 2010, and conflicting national standards shall be withdrawn at
the latest by October 2010.
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 12874:2001.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association, and supports essential requirements of EU Directive(s).
For relationship with EU Directive(s), see informative Annex ZA, which is an integral part of this document.
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 16852:2008, including Cor 1:2008 and Cor 2:2009 has been approved by CEN as a EN ISO
16852:2010 without any modification.
According to edition 2001 the following fundamental changes are given:
 explosion group IIA1, with a methane-air test mixture included;
 approval of in-line flame arrester (deflagration or detonation) limited to operational pressures less than or
equal to the applied test pressure;
 maximum limit for short time burning of 30 min extended;
 procedure for calculating the critical volume flow rate for endurance burning changed from a temperature
to a time based criterion;
 testing of high velocity vent valves revised;
 testing of flow controlled apertures deleted;
 types of detonation flame arresters extended to four types.
ISO 16852 has been developed from existing national and international standards on flame arresters. These
include the following standards: Z343-98 (Canada), 33CFR 154 (United States Coast Guard), UL 525
(Underwriter Laboratories, USA), IMO MSC/Circ. 677 (International Maritime Organization) and EN 12874
(European Committee for Standardization).
The requirements of ISO 16852 that deviate from those of EN 12874:2001 are detailed described below:
1) According its scope ISO 16852 is not applicable to flame arresters integrated in or combined with
explosion protected equipment. So, in terms of Directive 94/9/EC, ISO 16852 covers protective
systems only and not explosion protected equipment.
Furthermore ISO 16852 also does not cover other protective systems, which prevent flame
transmission by suppression or isolation of explosions; these different techniques find their reflection
in specific CEN standards.
2) ISO 16852 defines atmospheric conditions which comply with the "Guidelines on the Application of
Directive 94/9/EC, Section 4".
3) The requirements for ethylene-air test mixtures when expressed as “percent vapour in air by volume”
have been adjusted slightly as a result of more precise figures from re-evaluations of safe gap data
becoming available.
4) Specific requirements in EN 12874 on the strength of materials do not apply any more. The
international working group took the unanimous view that strength of equipment is sufficiently and
simultaneously proved by the explosion load generated by the flame transmission type tests.
5) All welded constructions are now required to undergo a routine pressure test.
6) An additional explosion group IIA1, with a methane-air test mixture, has been added to take account
of the increasing importance of biogenic generated explosive mixtures.
7) ISO 16852 extends the upper limit of the design series from 400 mm to 1000 mm flange connections.
8) For end-of-line flame arresters with non-measurable elements, the safety margin is achieved by
increasing the severity of the flame transmission test (higher test pressure) rather than requiring
thicker flame arrester elements in the production units.
9) Flame arresters for use with directly combined separate pressure-vacuum-valves shall be tested in
the same way as flame arresters that have integrated pressure-vacuum-valves.
10) For any in-line flame arrester (deflagration or detonation) the approval is limited to operational
pressures less than or equal to the applied test pressure. “Atmospheric testing” and subsequent
approval for operational pressures up to the limit of 1,1 bar absolute is not accepted under ISO 16852.
11) There are minor revisions of the pressure ratios characterizing unstable detonations and the range of
pipe sizes has been extended to 1000 mm and above.
12) For any in-line detonation arrester additional deflagration tests with a run-up length of five pipe
diameters are now required. The number of deflagration tests has also been increased from three to
five for each run-up length tested.
13) The classification of detonation arresters is widened from two types to four types, to include arresters
for stopping detonations in installations with pipe restrictions. Guidance on the proper use of a
detonation arrester type is given in the clause “Limits for use” and in the informative Annex D.
14) The period for the short time burning test has been extended from a 1 min limit to a maximum limit of
30 min. The test period is specified by the manufacturer of the flame arrester and has to be included
in the information marked on the flame arrester.
15) For endurance burn testing of static flame arresters, the procedure for calculating the critical volume
flow rate has been changed from a temperature to a time based criterion. This change was necessary
as a result of problems with applying the temperature criterion when testing large sizes of flame
arrester. The rest of the endurance burn test procedure is unchanged.
16) The procedure for testing high velocity vent valves has been extensively revised as a result of recent
test experience. The undamped oscillation testing of these devices (Annex A.4) has also been
revised.
17) The testing of flow controlled apertures is not covered by ISO 16852. This is mainly because the
safety of these devices largely depends on peripheral equipment and how they are installed, which
would not be assessed by the type tests specified in the standard.
18) Extension of the types of detonation arrester to four (Type 1 to Type 4) and the introduction of the
burn time classes (Burning Class a, b and c) were introduced to take account of the requirements of
the North American market. To aid the user in selecting the correct type of arrester for their
application from the many possible combinations of detonation type and burn class a warning label is
now required specifying the arrester type and its application limits.

Flame arresters shall be used as an integral part of a package of explosion protection measures to fulfil the
European ATEX directives. A risk assessment shall be used to develop a safety concept for the system to be
protected. This can then be used for selecting the correct type of arrester, for example a deflagration flame
arrester, stable detonation flame arrester or unstable detonation flame arrester, to provide the required level of
protection.
If the risk of an explosion is high it may be necessary to use more than one flame arrester, of different types,
to protect the system and in some cases in combination with other explosion protection measures.

Annex ZA
(informative)
Relationship between this European Standard and the Essential Requirements of
EU Directive 94/9/EC concerning equipment and protective systems for use in
potentially explosive atmospheres
This European Standard has been prepared under a mandate given to CEN by the European Commission
and the European Free Trade Association to provide a means of conforming to Essential Requirements of the
New Approach Directive 94/9/EC concerning equipment and protective systems for use in potentially
explosive atmospheres
Once this standard is cited in the Official Journal of the European Union under that Directive and has been
implemented as a national standard in at least one Member State, compliance with the clauses of this
standard given in table ZA confers, within the limits of the scope of this standard, a presumption of conformity
with the corresponding Essential Requirements of that Directive and associated EFTA regulations.
Table ZA — Correspondence between this European Standard and Directive 94/9/EC concerning
equipment and protective systems for use in potentially explosive atmospheres
Clause(s)/sub-clause(s) of this Essential Requirements (ERs) of Qualifying remarks/Notes
EN Directive 94/9/EC
Clause 5; 6.2; Annex D 1.0.1 Principles of integrated

explosion safety
6.2; 7.1 1.0.2 Design and manufacture

considerations
Annex C 1.0.3 Special checking and

maintenance conditions
6.2 1.0.4 Surrounding area
conditions
11.2 1.0.5 Marking
7.4; 8.4; 9.4; 10.3; 11.1 1.0.6 Instructions

6.2; 7.1; Annex C 1.1.1 Operational stresses on

material
6.2; Annex C 1.1.2 Reaction of material

6.2; 7.1 1.1.3 Wear of material

5.1; 6.2; 6.3; 6.4; 6.5; 7.1; 1.2.1 Design and construction

for safe operation
6.6 1.2.3 Enclosed structures and

prevention of leaks
11.1 1.2.5 Additional mans of
protection
7.3.4; 10.1 1.2.8 Overloading of equipment

6.3; 6.4; 7.3.2.3 1.2.9 Flameproof enclosure

systems
6.2 1.3.1 Hazards arising from

different ignition sources
Annex B; Annex C 1.3.2 Hazards arising from static

electricity
6.2 1.4.1 External effects
6.2 1.4.2 Mechanical, thermal and

chemical stresses
6.4 1.6.4 Hazards arising from

connections
6; 7; 8; 9; 10 3.0.1 Dimensioning

6; 7; 8; 9; 10 3.0.2 Design and position

6.5; 7.3.3 3.1.2 Shock waves
WARNING — Other requirements and other EU Directives may be applicable to the product(s) falling within
the scope of this standard.
INTERNATIONAL ISO
STANDARD 16852
First edition
2008-03-01
Flame arresters — Performance
requirements, test methods and limits
for use
Arrête-flammes — Exigences de performance, méthodes d'essai
et limites d'utilisation
Reference number
ISO 16852:2008(E)
©
ISO 2008
ISO 16852:2008(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.

©  ISO 2008
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 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 2008 – All rights reserved

ISO 16852:2008(E)
Contents Page
Foreword. v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 2
4 Symbols . 4
5 Hazards and flame arrester classifications. 6
5.1 Flame transmission: deflagration, stable and unstable detonation. 6
5.2 Flame transmission: stabilized burning. 7
6 General requirements. 7
6.1 Measuring instruments . 7
6.2 Construction. 7
6.3 Housings. 8
6.4 Joints. 8
6.5 Pressure test . 8
6.6 Leak test . 8
6.7 Flow measurement (air). 8
6.8 Flame transmission test. 9
6.9 Summary of tests to be conducted. 11
7 Specific requirements for static flame arresters . 12
7.1 Construction. 12
7.2 Design series. 12
7.3 Flame transmission test. 13
7.4 Limits for use . 26
8 Specific requirements for liquid product detonation flame arresters. 27
8.1 Liquid seals . 27
8.2 Foot valves . 28
8.3 Flame transmission test. 29
8.4 Limits for use . 30
9 Specific requirements for dynamic flame arresters (high velocity vent valves). 30
9.1 General. 30
9.2 Flame transmission test. 30
9.3 Endurance burning test. 31
9.4 Limits for use . 33
10 Specific requirements for hydraulic flame arresters . 33
10.1 Equipment . 33
10.2 Flame transmission test. 34
10.3 Limits for use . 35
11 Information for use . 37
11.1 Instructions for use . 37
11.2 Marking . 37
Annex A (normative) Flow measurement . 40
Annex B (informative) Information for selecting flame arresters. 44
Annex C (informative) Best practice. 45
ISO 16852:2008(E)
Annex D (informative) Use of in-line stable detonation flame arresters. 46
Bibliography . 47

iv © ISO 2008 – All rights reserved

ISO 16852:2008(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 16852 was prepared by Technical Committee ISO/TC 21, Equipment for fire protection and fire fighting.
ISO 16852:2008(E)
Introduction
Flame arresters are safety devices fitted to openings of enclosures or to pipe work, and are intended to allow
flow but prevent flame transmission. They have widely been used for decades in the chemical and oil industry,
and a variety of national standards is available. This International Standard was prepared by an international
group of experts, whose aim was to establish an international basis by harmonizing and incorporating recent
national developments and standards as far as reasonable.
This International Standard addresses manufacturers (performance requirements) and test institutes (test
methods), as well as customers (limits for use).
Only relatively general performance requirements are specified and these are kept to a strict minimum.
Experience has shown that excessively specific requirements in this field often create unjustified restrictions
and prevent innovative solutions.
The hazard identification of common applications found in industry leads to the specification of the test
methods. These test methods reflect standard practical situations and, as such, form the heart of this
International Standard because they also allow classification of the various types of flame arresters and then
determination of the limits of use.
A considerable number of test methods and test conditions had to be taken into account for two main reasons:
a) different types of flame arresters are covered with respect to the operating principle (static, hydraulic,
liquid, dynamic), and each type clearly needs its specific test set-up and test procedure;
b) it is necessary to adapt flame arresters to the special conditions of application (gas, installation) because
of the conflicting demands of high flame quenching capability and low pressure loss; this situation is
completely different from the otherwise similar principle of protection by flameproof enclosure (of electrical
equipment), where the importance of gas flow through gaps is negligible.
Consequently, in this International Standard, the testing and classification related to the gas groups and the
installation conditions has been subdivided more than is usually the case. In particular,
⎯ explosion group IIA is subdivided into sub-groups IIA1 and IIA,
⎯ explosion group IIB is subdivided into sub-groups IIB1, IIB2, IIB3 and IIB, and
⎯ the type “detonation arrester” is divided into four sub-types, which take into account specific installation
situations.
The test conditions lead to the limits for use which are most important for the customer. This International
Standard specifies this safety relevant information and its dissemination through the manufacturer's written
instructions for use and the marking of the flame arresters.
The limits for use are also a link to more general (operational) safety considerations and regulations, which
remain the responsibility of national or corporate authorities. Annexes B, C and D offer some guidance in this
field.
vi © ISO 2008 – All rights reserved

INTERNATIONAL STANDARD ISO 16852:2008(E)

Flame arresters — Performance requirements, test methods
and limits for use
1 Scope
This International Standard specifies the requirements for flame arresters that prevent flame transmission
when explosive gas-air or vapour-air mixtures are present. It establishes uniform principles for the
classification, basic construction and information for use, including the marking of flame arresters, and
specifies test methods to verify the safety requirements and determine safe limits of use.
This International Standard is valid for pressures ranging from 80 kPa to 160 kPa and temperatures ranging
from −20 °C to +150 °C.
NOTE 1 In designing and testing flame arresters for operation under conditions other than those specified above, this
International Standard can be used as a guide. However, additional testing related specifically to the intended conditions
of use is advisable. This is particularly important when high temperatures and pressures are applied. The test mixtures
might need to be modified in these cases.
This International Standard is not applicable to the following:
⎯ external safety-related measurement and control equipment that might be required to keep the
operational conditions within the established safe limits;
NOTE 2 Integrated measurement and control equipment, such as integrated temperature and flame sensors as
well as parts which, for example, intentionally melt (retaining pin), burn away (weather hoods) or bend (bimetallic
strips), is within the scope of this International Standard.
⎯ flame arresters used for explosive mixtures of vapours and gases, which tend to self-decompose (e.g.
acetylene) or which are chemically unstable;
⎯ flame arresters used for carbon disulphide, due to its special properties;
⎯ flame arresters whose intended use is for mixtures other than gas-air or vapour-air mixtures (e.g. higher
oxygen-nitrogen ratio, chlorine as oxidant, etc.);
⎯ flame arrester test procedures for internal-combustion compression ignition engines;
⎯ fast acting valves, extinguishing systems and other explosion isolating systems;
⎯ flame arresters integrated or combined with explosion-protected equipment, such as blowers, fans,
compressors and pumps.
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.
IEC 60079-1, Explosive atmospheres — Part 1: Equipment protection by flameproof enclosures “d”
ISO 16852:2008(E)
IEC 60079-1-1:2002, Electrical apparatus for explosive gas atmospheres — Part 1-1: Flameproof
enclosures “d” — Method of test for ascertainment of maximum experimental safe gap
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
flame arrester
device fitted to the opening of an enclosure, or to the connecting pipe work of a system of enclosures, and
whose intended function is to allow flow but prevent the transmission of flame
3.2
housing
portion of a flame arrester whose principal function is to provide a suitable enclosure for the flame arrester
element and allow mechanical connections to other systems
3.3
flame arrester element
portion of a flame arrester whose principal function is to prevent flame transmission
3.4
stabilized burning
steady burning of a flame stabilized at, or close to, the flame arrester element
3.5
short time burning
stabilized burning for a specified time
3.6
endurance burning
stabilized burning for an unlimited time
3.7
explosion
abrupt oxidation or decomposition reaction producing an increase in temperature, pressure, or in both
simultaneously
3.8
deflagration
explosion propagating at subsonic velocity
3.9
detonation
explosion propagating at supersonic velocity and characterized by a shock wave
3.10
stable detonation
detonation progressing through a confined system without significant variation of velocity and pressure
characteristics
NOTE For the atmospheric conditions, test mixtures and test procedures of this International Standard, typical
velocities range between 1 600 m/s and 2 200 m/s.
3.11
unstable detonation
detonation during the transition of a combustion process from a deflagration into a stable detonation
2 © ISO 2008 – All rights reserved

ISO 16852:2008(E)
NOTE The transition occurs in a limited spatial zone, where the velocity of the combustion wave is not constant and
where the explosion pressure is significantly higher than in a stable detonation. The position of this transition zone
depends, amongst other factors, on pipe diameter, pipe configuration, test gas and explosion group.
3.12 Characteristic safety data of explosive mixtures
3.12.1
maximum experimental safe gap
MESG
safe gap measured in accordance with IEC 60079-1-1:2002
3.12.2
explosion group
Ex.G
ranking of flammable gas-air mixtures with respect to the MESG
NOTE See Table 2, columns 1 and 2.
3.13
bi-directional flame arrester
flame arrester that prevents flame transmission from both sides
3.14
deflagration flame arrester
DEF
flame arrester designed to prevent the transmission of a deflagration
NOTE It can be an end-of-line flame arrester (3.21) or an in-line flame arrester (3.22).
3.15
detonation flame arrester
DET
flame arrester designed to prevent the transmission of a detonation
NOTE It can be an end-of-line flame arrester (3.21) or an in-line flame arrester (3.22), and can be used for both
stable detonations (3.10) and unstable detonations (3.11).
3.16
endurance burning flame arrester
flame arrester that prevents flame transmission during and after endurance burning
3.17
static flame arrester
flame arrester designed to prevent flame transmission by quenching gaps
3.17.1
measurable type
flame arrester where the quenching gaps of the flame arrester element can be technically drawn, measured and
controlled
3.17.2
non-measurable type
flame arrester where the quenching gaps of the flame arrester element cannot be technically drawn, measured
or controlled
EXAMPLE Random structures such as knitted mesh, sintered materials and gravel beds.
ISO 16852:2008(E)
3.18
dynamic flame arrester
high velocity vent valve
pressure relief valve designed to have nominal flow velocities that exceed the flame velocity of the explosive
mixture, thus preventing flame transmission
3.19
liquid product detonation flame arrester
flame arrester in which the liquid product is used to form a liquid seal as a flame arrester medium, in order to
prevent flame transmission of a detonation
NOTE There are two types of liquid product detonation flame arrester for use in liquid product lines: liquid seals and
foot valves.
3.19.1
liquid seal flame arrester
flame arrester designed to use the liquid product to form a barrier to flame transmission
3.19.2
foot valve flame arrester
flame arrester designed to use the liquid product combined with a non-return valve to form a barrier to flame
transmission
3.20
hydraulic flame arrester
flame arrester designed to break the flow of an explosive mixture into discrete bubbles in a water column, thus
preventing flame transmission
3.21
end-of-line flame arrester
flame arrester that is fitted with one pipe connection only
3.22
in-line flame arrester
flame arrester that is fitted with two pipe connections, one on each side of the flame arrester
3.23
pre-volume flame arrester
flame arrester that, after ignition by an internal ignition source, prevents flame transmission from inside an
explosion-pressure-resistant containment (e.g. a vessel or closed pipe work) to the outside, or into the
connecting pipe work
NOTE Explosion-pressure resistance is a property of vessels and equipment designed to withstand the expected
explosion pressure without becoming permanently deformed.
3.24
integrated temperature sensor
temperature sensor integrated into the flame arrester, as specified by the manufacturer of the flame arrester,
in order to provide a signal suitable to activate counter measures
3.25
atmospheric conditions
conditions with pressures ranging from 80 kPa to 110 kPa and temperatures ranging from −20 °C to +60 °C
4 Symbols
A free area of a static flame arrester element
A nominal cross sectional area of the flame arrester connection
p
4 © ISO 2008 – All rights reserved

ISO 16852:2008(E)
A cross sectional area on the unprotected side of the flame arrester element
t
A effective open area of the flame arrester element on the protected side
u
D pipe diameter
D minimum diameter of the pipe on the protected side of a dynamic flame arrester
M
L maximum length without undamped oscillations
M
L pipe length upstream of the dynamic flame arrester used in flame transmission test
m
L pipe length on the protected side
p
L pipe length between flame arrester and restriction

r
L pipe length on the unprotected side, maximum allowable run-up length for installation
u
L , L , L , L pipe lengths in the flow test
1 2 3 4
p time average value of the detonation pressure in the time interval of 200 µs after arrival of the
md
detonation shock wave
p maximum time average value of the transient pressure of an unstable detonation over a time
mu
interval of 200 µs
p pressure in the pressure test
t
p pressure in the flow test of an end-of-line flame arrester
T
p pressure before ignition
TB
p maximum operational pressure
∆p pressure drop in the flow test of an in-line flame arrester
R ratio of the effective open area of the flame arrester element to pipe cross sectional area
A
R ratio of the free volume of the flame arrester element to the whole volume
U
t burning time
BT
T temperature of the flame arrester before ignition
TB
T maximum operational temperature of the flame arrester
v laminar burning velocity
I
v maximum flow velocity during the volume flow-pressure drop measurement (flow test)
max
v minimum flow velocity during the volume flow-pressure drop measurement (flow test)
min
&
V volume flow rate
&
critical volume flow rate
V
c
&
V flow rate at closing point of dynamic flame arresters
CL
&
minimum volume flow rate for endurance burning on dynamic flame arresters
V
&
maximum volume flow rate for endurance burning on dynamic flame arresters
V
E
ISO 16852:2008(E)
&
maximum volume flow rate for dynamic flame arresters at the set pressure
V
K
&
volume flow rate leading to maximum temperature
V
m
V minimum volume in the protected tank
M
&
safe volume flow rate
V
max
&
safe volume flow rate including a safety margin
V
s
&
maximum volume flow rate leading to flame transmission
V
t
Z minimum water seal immersion depth at rest above the outlet openings of the immersion tubes

Rmin
Z immersion depth at rest, corresponding to Z plus the manufacturer's recommended safety
R Rmin
margin
Z minimum operational water seal immersion depth when the mixture flow displaces the water
0min
from the immersion tubes, where Z > Z
0min Rmin
Z operational immersion depth, corresponding to Z plus the manufacturer's recommended
0 0min
safety margin
NOTE All pressure values are absolute pressures.
5 Hazards and flame arrester classifications
5.1 Flame transmission: deflagration, stable and unstable detonation
The ignition of an explosive mixture will initiate a deflagration. A flame arrester covering only this hazard is
classified as a deflagration flame arrester.
A deflagration when confined in a pipe may accelerate and undergo transition through an unstable to a stable
detonation, provided sufficient pipe length is available. This pipe length may vary depending upon the initial
conditions of the mixture and the pipe work configuration.
A flame arrester tested in accordance with 7.3.3.2 or 7.3.3.3 is classified as a stable detonation flame arrester
and is suitable for deflagrations and stable detonations.
Unstable detonations are a specific hazard requiring higher performance flame arresters than for stable
detonations.
A flame arrester tested in accordance with 7.3.3.4 or 7.3.3.5 is classified as an unstable detonation flame
arrester and is suitable for deflagrations, stable detonations and unstable detonations.
These hazards relate to specific installations and in each case the flame arrester successfully tested at p is
TB
suitable for operational pressures p u p , and the application is limited to mixtures with an MESG equal to or
0 TB
greater than that tested.
The specific hazards covered by this International Standard, the classification and the testing required for the
appropriate flame arrester are listed in Table 1.
6 © ISO 2008 – All rights reserved

ISO 16852:2008(E)
Table 1 — Flame arrester classification for deflagration, stable and unstable detonation
Application Flame arrester classification
end-of-line deflagration
a) unconfined deflagration into an enclosure or vessel
b) confined deflagration propagating along a pipe into connecting pipe work in-line deflagration
c) deflagration confined by an enclosure or pipe work to the outside
pre-volume deflagration
atmosphere or into connecting apparatus
d) stable detonation propagating along a pipe into connecting pipe work in-line stable detonation
e) unstable detonation propagating along a pipe into connecting pipe work in-line unstable detonation
end-of-line stable detonation
f) stable detonation into an enclosure or vessel

5.2 Flame transmission: stabilized burning
Stabilized burning after ignition creates additional hazards in applications where there could be a continuous
flow of the explosive mixture towards the unprotected side of the flame arrester. The following situations shall
be taken into account:
⎯ if the flow of the explosive mixture can be stopped within a specific time that is between 1 min and 30 min,
flame arresters which prevent flame transmission during that period of stabilized burning are suitable for
that hazard, and they are classified as safe against short time burning;
NOTE Bypassing, sufficient diluting or inerting are measures equivalent to stopping the flow.
⎯ if the flow of the explosive mixture cannot be stopped or, for operational reasons, is not intended to be
stopped within 30 min, flame arresters which prevent flame transmission for this type of stabilized burning
are suitable for that hazard, and they are classified as safe against endurance burning.
6 General requirements
6.1 Measuring instruments
Appropriate and calibrated measuring instruments shall be used for the tests.
NOTE It is advisable that the uncertainty of measurement in the tests be such that it can be shown that all the
required test parameter limits are met.
6.2 Construction
All parts of the flame arrester shall resist the expected mechanical, thermal and chemical loads for the
intended use.
Production flame arresters shall have flame quenching capabilities no less than the tested flame arrester.
Light metal alloys shall not contain more than 6 % magnesium. Coatings of components which may be
exposed to flames during operation shall not be damaged in a way that makes flame transmission possible.
Flame arresters for short time burning shall be fitted with one or more integrated temperature sensors, taking
into account the intended orientation of the flame arrester.
...