Explosion Isolation Systems

This European Standard describes the general requirements for explosion isolation systems. This standard specifies methods for evaluating the efficacy of the various explosion isolation systems, and methods for evaluating design tools for such explosion isolation systems when applying these in practice.
It is noted that such explosion isolation systems, when defined, attested, and installed in accordance with the requirements of this European Standard have a high degree of operational efficacy. However it is not practical to completely eliminate the risk of explosion propagation beyond the boundaries of the isolation barrier for all scenarios of ignition location and explosion circumstance, and the selection and incorporation of such explosion isolation systems in any explosion safety concept should take into account this small residual risk.
This European Standard also sets out the criteria for alternative test methods and interpretation means to validate the efficacy of explosion isolations.
It covers e.g.:
a)   general requirements for the explosion isolation components;
b)   evaluating the effectiveness of an explosion isolation system;
c)   evaluating design tools for explosion isolation systems;
d)   installation requirements for explosion isolation systems;
e)   maintenance requirements for explosion isolation systems.
This European Standard is applicable only to the use of explosion isolation systems that are intended for avoiding explosion propagation between interconnected enclosures in which an explosion may result as a consequence of ignition of an explosible mixtures e.g., dust-air mixtures, gas-(vapour-)air mixtures, dust-, gas-(vapour-)air mixtures and mists.
This standard does not cover flame arresters. For this devices refer to EN 12874.
This standard is only applicable for explosions of chemicals, stable materials and mixtures of these (flame propagating at subsonic velocity). This standard is not applicable for explosions of materials listed belo

Explosionsentkopplungs-Systeme

Die vorliegende Europäische Norm beschreibt die grundlegenden Anforderungen an Explosionsentkopplungs-Systeme. Diese Norm legt Verfahren zur Bewertung der Wirksamkeit verschiedener Explosionsentkopplungs-Systeme und Verfahren zur Beurteilung von Dimensionierungsmethoden für derartige Explosionsentkopplungs-Systeme bei der praktischen Anwendung fest.
Es ist zu erwähnen, dass derartige Explosionsentkopplungs-Systeme bei Definition, Zertifizierung und Installation entsprechend den Anforderungen dieser Europäischen Norm einen hohen Grad an funktioneller Wirksamkeit aufweisen. Die vollständige Beseitigung des Risikos der Explosionsweiterleitung über die Grenzen der Entkopplungsbarriere hinaus ist jedoch für alle Explosionsszenarien hinsichtlich Zündort und Explosionsumstände praktisch unmöglich und dieses geringe Restrisiko sollte bei der Einbindung derartiger Explosionsentkopplungs-Systeme in ein Explosionssicherheitskonzept berücksichtigt werden.
Diese Europäische Norm legt auch die Kriterien für alternative Prüfverfahren und Interpretationsmittel zum Bewerten der Wirksamkeit von Explosionsentkopplungen offen.
Behandelt werden z. B.:
a)   grundlegende Anforderungen an Explosionsentkopplungs-Bauelemente;
b)   Beurteilung der Wirksamkeit eines Explosionsentkopplungs-Systems;
c)   Beurteilung von Dimensionierungsmethoden für Explosionsentkopplungs-Systeme;
d)   Installationsanforderungen für Explosionsentkopplungs-Systeme;
e)   Wartungsanforderungen für Explosionsentkopplungs-Systeme.
Diese Europäische Norm gilt nur für die Anwendung von Explosionsentkopplungs-Systemen, die zum Verhindern der Explosionsweiterleitung zwischen miteinander verbundenen Gehäusen/Behältern, in denen eine Explosion als Folge einer Entzündung eines explosionsfähigen Gemischs, z. B. Staub-Luft-Gemische, Gas-(Dampf-)Luft-Gemische, Staub-Gas-(Dampf-)Luft-Gemische und Nebel, eintreten kann, vorgesehen sind.
Flammendurchschlagsicherungen werden von dieser Norm nicht berücksichtigt. Hierfür wird auf EN

Systeme d'Explosion Isolation

La présente Norme européenne décrit les exigences générales relatives aux systèmes d'isolement d'une explosion. Un système d'isolement d'une explosion a pour but d’empêcher une onde de pression d'explosion et une flamme, ou uniquement une flamme, de se propager vers d'autres parties des équipements ou vers d'autres zones de l'installation, par l'intermédiaire de canalisations ou de conduites de raccordement. Ces normes européennes exposent les méthodes qui permettent d’évaluer l'efficacité des différents systèmes d'isolement, ainsi que les méthodes d'évaluation des outils de conception destinés à ces systèmes lors de leur mise en œuvre.
La présente Norme européenne expose également les critères requis pour d’autres méthodes d’essai ainsi que des moyens d’interprétation destinés à valider les systèmes d'isolement d'une explosion.
Elle couvre par exemple :
a)   les exigences générales relatives aux composants des systèmes d'isolement d'une explosion ;
b)   l’évaluation de l’efficacité d’un système d'isolement d'une explosion ;
c)   l’évaluation des outils de conception destinés à des systèmes d'isolement d'une explosion.
La présente Norme européenne est uniquement applicable aux systèmes d'isolement d'une explosion qui ont pour but d'éviter une propagation de l’explosion entre des enveloppes communicantes dans lesquelles l'explosion résulte de l'inflammation d'une atmosphère explosive, constituée d'un mélange avec l'air de poussière, de gaz-(vapeur), d'un mélange hybride de poussière et de gaz-(vapeur), ou de brouillard.
En règle générale, les systèmes d’isolement d’une explosion ne sont pas conçus pour empêcher la transmission du feu ou de la poudre de combustion qui peuvent déclencher une explosion en aval de l’installation. Il est important de prendre en compte ces éléments dans l’évaluation des risques.
[...]

Sistemi za ločitev eksplozij

General Information

Status
Published
Publication Date
12-May-2009
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
12-May-2009
Due Date
17-Jul-2009
Completion Date
13-May-2009

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Explosionsentkopplungs-SystemeSysteme d'Explosion IsolationExplosion Isolation Systems13.230Varstvo pred eksplozijoExplosion protectionICS:Ta slovenski standard je istoveten z:EN 15089:2009SIST EN 15089:2009en,fr,de01-julij-2009SIST EN 15089:2009SLOVENSKI

STANDARD
SIST EN 15089:2009

EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 15089March 2009ICS 13.230 English VersionExplosion isolation systemsSystème d'isolation d'explosionExplosions-EntkopplungssystemeThis European Standard was approved by CEN on 7 February 2009.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards 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 translationunder the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as theofficial versions.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, 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 STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre:

Avenue Marnix 17,

B-1000 Brussels© 2009 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 15089:2009: ESIST EN 15089:2009

EN 15089:2009 (E) 2 Contents Page Foreword ..............................................................................................................................................................4 1 Scope ......................................................................................................................................................5 2 Normative references ............................................................................................................................5 3 Terms and definitions ...........................................................................................................................6 4 Explosion isolation systems ................................................................................................................8 4.1 General ....................................................................................................................................................8 4.2 Isolation types ........................................................................................................................................8 4.2.1 Passive isolation type ...........................................................................................................................8 4.2.2 Active isolation type ..............................................................................................................................8 5 Requirements of explosion isolation components ............................................................................8 5.1 General ....................................................................................................................................................8 5.2 Detection devices ..................................................................................................................................9 5.2.1 General ....................................................................................................................................................9 5.2.2 Optical detection ....................................................................................................................................9 5.2.3 Pressure detection.................................................................................................................................9 5.2.4 Other actuation ......................................................................................................................................9 5.3 Indicating equipment (IE) and control and indicating equipment (CIE) ...........................................9 5.3.1 General ....................................................................................................................................................9 5.3.2 Indicating equipment .............................................................................................................................9 5.3.3 Control and indicating equipment .......................................................................................................9 5.4 Safety integrity of control and indicating equipment (CIE) ............................................................ 10 5.4.1 General ................................................................................................................................................. 10 5.4.2 Measures to avoid and control systematic faults ........................................................................... 10 5.4.3 Control of electric connections ......................................................................................................... 10 5.4.4 Indicators and messages on CIE ...................................................................................................... 10 5.4.5 Energy supply ..................................................................................................................................... 10 5.5 Explosion isolation devices ............................................................................................................... 10 5.5.1 General ................................................................................................................................................. 10 5.5.2 Explosion protection valve (active or passive) – F&P .................................................................... 11 5.5.3 Extinguishing barrier (active) – F ...................................................................................................... 11 5.5.4 Rotary valve (passive) – F .................................................................................................................. 11 5.5.5 Explosion proof interlocked double valve arrangement (passive) – F&P .................................... 11 5.5.6 Diverters, explosion isolation flaps and flame arresters ................................................................ 11 6 System design ..................................................................................................................................... 11 6.1 General ................................................................................................................................................. 11 6.2 Combination of explosion isolation systems with other explosion protection techniques ....... 12 6.2.1 Explosion resistant design for the maximum explosion pressure – isolation ............................. 12 6.2.2 Venting – isolation .............................................................................................................................. 12 6.2.3 Suppression – isolation ..................................................................................................................... 13 7 Experimental testing of the efficacy of an explosion isolation system ........................................ 13 7.1 General ................................................................................................................................................. 13 7.2 Test Modules ....................................................................................................................................... 13 7.2.1 General ................................................................................................................................................. 13 7.2.2 Module A: Explosion resistance testing .......................................................................................... 14 7.2.3 Module B: Flameproof testing ........................................................................................................... 15 7.2.4 Module C: Functional testing ............................................................................................................ 16 7.3 Testing Report ..................................................................................................................................... 27 8 Information for use ............................................................................................................................. 28 SIST EN 15089:2009

EN 15089:2009 (E) 3 9 Marking ................................................................................................................................................. 28 9.1 Marking of the explosion isolation system ....................................................................................... 28 9.2 Marking of components of an explosion isolation system ............................................................. 29 Annex A (informative)

Verification of design methods ................................................................................. 30 A.1 General .................................................................................................................................................. 30 A.2 Design on the basis of an interpretation of test results .................................................................. 31 A.3 Mathematical model ............................................................................................................................ 32 Annex ZA (informative)

Relationship between this
European

Standard and the Essential Requirements of EU Directive 94/9/EC ....................................................................................................................... 35 Bibliography ...................................................................................................................................................... 37 Figures Figure 1 — Test arrangement for pressure resistance testing and high-pressure flame proof testing . 15 Figure 2 — Test arrangement for flameproof testing .................................................................................. 16 Figure 3 — Test arrangement for functional testing for passive explosion protection valves ............... 17 Figure 4 — Test arrangement for functional testing for active isolation valves ....................................... 20 Figure 5 — Test arrangement for functional testing for extinguishing barriers ....................................... 23 Figure 6 — Test arrangement for functional testing for rotary valves ....................................................... 26 Figure A.1 — Example of interpolating the minimum and maximum distance of an active explosion valve for enclosure volumes between 1 m³ to 10 m³, triggering device: pressure detection on the enclosure (pa = 0,1 bar) ............................................................................................................................ 31 Figure A.2 — Effect of ignition location, detection system and K-value on minimum installation distance ..................................................................................................................................................... 33 Tables Table 1 — Type of modules as a function of type of isolation device ....................................................... 14 Table 2 — Location of ignition source for verification/determination of the minimum installation distance ..................................................................................................................................................... 19 Table 3 — Location of ignition source to be used for verification/determination of the minimum installation distance ................................................................................................................................. 21 Table 4 — Location of ignition source to be used for verification/determination of the minimum installation distance using flame detection only .................................................................................. 24 Table A.1 — Important criteria, which can influence the design/installation distance of an isolation device......................................................................................................................................................... 30 Table ZA — Correspondence between this European Standard and Directive 94/9/EC .......................... 35

SIST EN 15089:2009

EN 15089:2009 (E) 4 Foreword This document (EN 15089:2009) has been prepared 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 September 2009, and conflicting national standards shall be withdrawn at the latest by September 2009. 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 has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association, and supports essential requirements of EC Directive(s). For relationship with EC 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, 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. SIST EN 15089:2009

EN 15089:2009 (E) 5

1 Scope This European Standard describes the general requirements for explosion isolation systems. An explosion isolation system is a protective system, which prevents an explosion pressure wave and a flame or only a flame from propagating via connecting pipes or ducts into other parts of apparatus or plant areas. This European Standard specifies methods for evaluating the efficacy of the various explosion isolation systems, and methods for evaluating design tools for such explosion isolation systems when applying these in practice. This European Standard also sets out the criteria for alternative test methods and interpretation means to validate the efficacy of explosion isolations. It covers e.g.: a) general requirements for the explosion isolation components; b) evaluating the effectiveness of an explosion isolation system; c) evaluating design tools for explosion isolation systems. This European Standard is applicable only to the use of explosion isolation systems that are intended for avoiding explosion propagation between interconnected enclosures, in which an explosion may result as a consequence of ignition of an explosive mixtures e.g., dust-air mixtures, gas-(vapour-)air mixtures, dust-, gas-(vapour-)air mixtures and mists. In general explosion isolation systems are not designed to prevent the transmission of fire or burning powder either of which can initiate an explosion in downstream plant items. It is necessary to take this situation into account in risk assessments. This European Standard is only applicable for gas and dust explosions of chemically stable substances and mixtures of these (flame propagating at subsonic velocity). This European Standard is not applicable for explosions of materials listed below, or for mixtures containing some of those materials: i) chemically unstable substances that are liable to decompose; ii) explosive substances; iii) pyrotechnic substances. This European Standard does not cover flame arresters. For these devices refer to EN 12874. 2 Normative references The following reference 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. EN 12874:2001, Flame arresters – Performance requirements, test methods and limits for use EN 13237, Potentially explosive atmospheres – Terms and definitions for equipment and protective systems intended for use in potentially explosive atmospheres EN 13673-1, Determination of the maximum explosion pressure and the maximum rate of pressure rise of gases and vapours – Part 1: Determination of the maximum explosion pressure SIST EN 15089:2009

EN 15089:2009 (E) 6 EN 13673-2, Determination of maximum explosion pressure and the maximum rate of pressure rise of gases and vapours – Part 2: Determination of the maximum rate of explosion pressure rise EN 14034-1, Determination of explosion characteristics of dust clouds – Part 1: Determination of the maximum explosion pressure pmax of dust clouds EN 14034-2, Determination of explosion characteristics of dust clouds – Part 2: Determination of the maximum rate of explosion pressure rise (dp/dt)max of dust clouds EN 14373, Explosion suppression systems 3 Terms and definitions For the purposes of this document, the terms and definitions given in EN 13237, EN 14373 and the following apply. 3.1 indicating equipment IE explosion protection equipment, which monitors the explosion sensors/detectors and the explosion protection devices 3.2 closing time time needed for closing an isolation device 3.3 closing time of the system sum of the activation time of sensor, activation time of isolation device and closing time of the isolation device 3.4 design strength of enclosure p (plant strength) 3.4.1 explosion-pressure-resistant property of vessels and equipment designed to withstand the expected explosion pressure without becoming permanently deformed [EN 13237:2003, 3.31] 3.4.2 explosion-pressure-shock-resistant property of vessels and equipment designed to withstand the expected explosion pressure without rupturing, but allowing permanent deformation [EN 13237:2003, 3.32] 3.5 explosion abrupt oxidation or decomposition reaction producing an increase in temperature, pressure, or in both simultaneously [EN 13237:2003, 3.28] 3.6 explosion diverter mechanical device, which will divert the explosion to a safe area NOTE It prevents flame jet ignition and pressure piling but cannot effectively stop explosions from travelling. SIST EN 15089:2009

EN 15089:2009 (E) 7 3.7 explosion isolation system 3.7.1 active explosion isolation system system which is designed to stop explosions from travelling through pipelines or limit the associated destructive effects of the explosion and is activated by detectors and a control and indicating equipment (CIE), which are parts of the system 3.7.2 passive explosion isolation system system which is designed to stop explosions from travelling through pipelines or limit the associated destructive effects of the explosion and does not require detectors and a control and indicating equipment (CIE) 3.8 explosion isolation valve fast acting valve able to stop explosions from travelling through pipelines 3.9 explosion proof interlocked double valve arrangement device, which will act in closed position as isolation valve 3.10 explosion isolation flap hinged door which is kept in open position by the air flow and closes by gravity when the air flow is interrupted 3.11 extinguishing barrier system that is used to discharge suppressant agent into ductwork to isolate a flame and keep it from propagating to other process areas 3.12 extinguishing distance needed distance behind an extinguishing barrier to guarantee a proper isolation of the flame of an explosion 3.13 flame arrester device fitted to the opening of an enclosure or to the connecting pipework of a system of enclosures and whose intended function is to allow flow but prevent the transmission of flame [EN 12874:2001, 3.1.1] 3.14 flame velocity Sf velocity of a flame front relative to a fixed reference point 3.15 installation distance 3.15.1 maximum installation distance longest distance from the outlet of the enclosure with the potential explosion to the isolation system, which is limited by the explosion resistance of the isolation device or pipe but still guaranteeing a successful isolation 3.15.2 minimum installation distance shortest distance from the outlet of the enclosure with the potential explosion to the isolation system guaranteeing a successful isolation SIST EN 15089:2009

EN 15089:2009 (E) 8 3.16 minimum ignition energy MIE lowest energy which is sufficient to effect ignition of the most easily ignitable explosive atmosphere under specified test conditions [EN 13237:2003, 3.85] 3.17 minimum ignition temperature of an explosive atmosphere MIT ignition temperature of a combustible gas or of a vapour of a combustible liquid or the minimum ignition temperature of a dust cloud under specified test conditions 3.18 response time time necessary for actuation of the system after a detection of an explosion 4 Explosion isolation systems 4.1 General Explosion isolation is achieved by a protective system, which prevents an explosion pressure wave and a flame or only a flame from propagating via connecting pipes or ducts into other parts of apparatus or plant areas. Systems providing complete isolation by operation of the isolation device(s) prevent the propagation of the flame as well as pressure effects. Systems providing partial isolation only isolate the flame propagation. This distinction is important for practical application, because it is not necessary in all cases to achieve a complete isolation of flame and pressure. In some cases it is sufficient to achieve only flame isolation. 4.2 Isolation types 4.2.1 Passive isolation type Passive isolation systems do not require the addition of detection and control and indicating equipment to function. 4.2.2 Active isolation type Active isolation systems require detection and control and indicating equipment to function. Detection systems are systems usually based on optical or pressure sensors. 5 Requirements of explosion isolation components 5.1 General To prevent an explosion occurring in a protected installation from spreading through a pipeline to another part of the installation, explosion isolation measures shall be implemented. Therefore isolation is normally installed into a pipe which connects two enclosures. It can also be located immediately after equipment e.g., a rotary valve underneath the cone of a filter or silo. As explosions are generally propagated by flames and not by the pressure waves, it is especially important to detect, extinguish or block this flame front at an early stage, i.e. to isolate the explosion. SIST EN 15089:2009

EN 15089:2009 (E) 9 5.2 Detection devices 5.2.1 General To initiate an active explosion isolation system one or more detectors are used to detect either an explosion pressure wave or flame of a propagating explosion. Each detector provides a signal to the CIE unit. It is important to locate the detector in its correct position, to ensure sufficient time for the isolation system to detect and activate the isolation device to stop the explosion. NOTE In many cases it is favourable to use a combination of a pressure detector in the enclosure and an optical detector in the pipe, and they should be switched in an OR-type of logic for activating the isolation device. 5.2.2 Optical detection Detection of a flame can be achieved using UV, IR or visible radiation sensors. It is important to mount the detector so that the angle of vision allows it to cover the full area to be monitored. The performance of an optical sensor will also be affected by any obstacles within its vision, which can be overcome by the introduction of more detectors. It shall be assured that the optical lenses of the sensors are kept clean, e.g. by air shields. 5.2.3 Pressure detection Threshold detectors provide a signal when a pre-set overpressure – pa (the systems activation pressure) – is exceeded. Dynamic detectors have rate-of-pressure rise triggering points and may include additional pressure threshold triggering points. Although this type of detector minimises spurious activation of the isolation system (due to pressure fluctuations other than explosion pressure rise), care shall be taken to set-up such detectors to meet appropriate detection response criteria for the particular application and protected geometry. 5.2.4 Other actuation Bursting discs, vent panels or explosion doors can be fitted with switches or break wires, which actuate an isolation system. 5.3 Indicating equipment (IE) and control and indicating equipment (CIE) 5.3.1 General Whether control and indicating equipment (CIE) or so-called indicating equipment (IE) is to be used on an isolation device/system is dependant on the type of protection device. IE will only indicate the status of the device; CIE will actively control the operation of the protection device and provide status indication of the device and is therefore critical for the correct functioning of the device/system. 5.3.2 Indicating equipment Indicating equipment (IE) monitors and provides the status indication only of the isolation device/system. 5.3.3 Control and indicating equipment Control and indicating equipment (CIE) records and monitors the signals transmitted by the system detectors. Dependent on configuration, by interrogation and interpretation of the detector data the CIE selectively controls the actuation of protection device, process equipment shut down (direct or indirect) and all audible and visual alarms. System internal monitoring gives fault indication in the event of device or field wiring defect, and alarm and fault relay contacts shall be connected as appropriate. Emergency standby power shall be facilitated such that full explosion protection is assured during any power failure. System isolation to facilitate safe working on or in a protected enclosure shall be implemented. SIST EN 15089:2009

EN 15089:2009 (E) 10 5.4 Safety integrity of control and indicating equipment (CIE) 5.4.1 General The following requirements are intended to ensure the safety integrity for active systems. 5.4.2 Measures to avoid and control systematic faults Systematic and transparent system analyses shall be made in all design stages to prevent potential defects. This methodical and comprehensible design approach ensures a clearly specified level of functional safety for any kind of product (see e.g. EN 15233). 5.4.3 Control of electric connections As a minimum, the electric connections for the following equipment shall be monitored for short circuit, open circuit and earth faults: a) detector(s); b) protection isolation device(s). In case of an identifiable fault such that the safety function of the system cannot be guaranteed to the agreed level of safety integrity, the explosion isolation system shall provide a fail-safe means to place the installation into a safe condition. 5.4.4 Indicators and messages on CIE The activation and fault messages shall be shown and indicated at the CIE indicating its origin and nature. In case of activation of the explosion isolation device/system, the CIE shall provide a means to commence an emergency stop procedure of the protected installation. 5.4.5 Energy supply For the energy supply of the CIE two independent energy sources shall be available. Where batteries are applied, they shall be suitable for the local operation and maintain a sufficient charge. Batteries, where used as a back-up power supply, shall supply a minimum of 4 hours. The power supply shall be independent and suitably protected, and shall not be de-activated by an emergency switch. After loss of the back-up power supply the CIE shall activate an emergency stop procedure of the protected installation. 5.5 Explosion isolation devices 5.5.1 General The following is a list of explosion isolation devices. The different objectives to be addressed can be summarized as follows: Flame (F): objective is to stop flame propagation. The protected area is defined as the point beyond the isolation device, opposite to the ignition source. Pressure (P): objective is to stop the pressure wave from travelling beyond the isolation device. The explosion resistance of the equipment of the isolation device shall meet the expected pressure according to the intended use. SIST EN 15089:2009

EN 15089:2009 (E) 11 5.5.2 Explosion protection valve (active or passive) – F&P To prevent flame and pressure propagation in pipes and ducts, valves or gates may be used which close in a sufficient short time. The closure can be affected by means of an actuating mechanism initiated by a pressure detector or a flame detector or a combination thereof or by the explosion overpressure itself. NOTE Explosion protection valves need not be gas tight. 5.5.3 Extinguishing barrier (active) – F The extinguishing medium is dispersed into the pipeline and the flame extinguished. The extinguishing medium shall be suitable for the specific explosive atmosphere. 5.5.4 Rotary valve (passive) – F The effectiveness of the rotary valve against flame propagation and its explosion resistance shall be proven.

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