Explosion diverters

An explosion diverter is used to divert explosions propagating through ducts. The device is used to prevent flame jet ignition and pressure piling in connected protected enclosures when designed correctly. The standard is specifying the basic requirements for the design and application of explosion diverters. The standard is specifying methods for assessing the efficacy of explosion diverters and present scale-up criteria. It is noted that an explosion diverter cannot be used as an explosion isolation device since flame transmission cannot effectively be prevented. The standard is only considering diverting of explosions propagating in flammable dustair, gas (vapour)-air, mist-air mixtures or hybrids thereof.

Explosionsschlote

Diese Norm legt die grundlegende Gestaltung für Rohr in Rohr Explosionsschlote sowie die Prüfan-forderungen und Anwendungen für Explosionsschlote fest. Außerdem werden Verfahren zur Bewertung der Wirksamkeit von Explosionsschloten festgelegt.
Ein Explosionsschlot wird zum Ableiten von Explosionen verwendet, die sich in Rohrleitungen ausbreiten. Bei sachgemäßer Auslegung verhindern diese Einrichtungen eine Flammenstrahlzündung und einen Druck-aufbau in angrenzenden geschützten Gehäusen. Das Risiko einer Flammenübertragung wird verringert.
In der Norm sind festgelegt:
   ein Prüfverfahren zur Bewertung der Wirksamkeit von Explosionsschloten;
   Gestaltungsregeln für einen Typ eines Rohr in Rohr Explosionsschlotes;
   Anforderungen an die Druckentlastungseinrichtung am Explosionsschlot;
   Installationsanforderungen;
   Wartungsanforderungen;
   Kennzeichnung.
Diese Norm gilt nur für explosionsfähige Staub/Luft Gemische.

Dispositifs déviateurs d'explosion

La présente Norme spécifie la conception de base d'un dispositif déviateur à tuyau interne et les exigences d'essai ainsi que l'application des dispositifs déviateurs d'explosion. La norme spécifie également les méthodes destinées à évaluer l'efficacité des dispositifs déviateurs d'explosion.
Un dispositif déviateur d'explosion est utilisé pour dévier des explosions qui se propagent dans des canalisations. Lorsqu'il est conçu correctement, le dispositif empêchera l'inflammation par jet de flamme et la pré-compression dans les enceintes protégées et reliées. Il diminuera le risque de transmission de la flamme.
La norme englobe :
a)   une méthode d'essai destinée à évaluer l'efficacité des dispositifs déviateurs d’explosion,
b)   des règles de conception pour un type de déviateur à tuyau interne,
c)   des exigences portant sur le dispositif d‘évent situé sur le déviateur,
d)   les exigences d'installation,
e)   les exigences de maintenance,
f)   le marquage.
La présente Norme considère seulement les atmosphères explosives de mélanges poussière/air.

Preusmerjevalniki eksplozij

Preusmerjevalnik eksplozij se uporablja za preusmerjanje eksplozij, ki se širijo prek kablov. Naprava se uporablja za preprečevanje vžiga plamena in kopičenje tlaka v povezavi z zaščitenimi ohišji, če je pravilno načrtovana. Ta standard določa osnovne zahteve za načrtovanje in uporabo preusmerjevalnikov eksplozij. Ta standard določa metode za ocenjevanje učinkovitosti preusmerjevalnikov eksplozij in trenutna merila za njeno povečanje. Treba je opozoriti, da se preusmerjevalnik eksplozij ne more uporabljati kot naprava za izolacijo eksplozije, saj prenosa plamena ni mogoče učinkovito preprečiti. Ta standard obravnava le preusmerjanje eksplozij, ki se širijo na vnetljiv prašni zrak, zrak s plinom (hlapi), mešanice zrak-meglica ali njihove hibride.

General Information

Status
Published
Publication Date
13-Sep-2011
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
06-Sep-2011
Due Date
11-Nov-2011
Completion Date
14-Sep-2011

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Preusmerjevalniki eksplozijExplosionsschloteDispositifs déviateurs d'explosionExplosion diverters13.230Varstvo pred eksplozijoExplosion protectionICS:Ta slovenski standard je istoveten z:EN 16020:2011SIST EN 16020:2011en,de01-oktober-2011SIST EN 16020:2011SLOVENSKI

STANDARD
SIST EN 16020:2011
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 16020
July 2011 ICS 13.230 English Version
Explosion diverters
Dispositifs déviateurs d'explosion
Explosionsschlote This European Standard was approved by CEN on 25 June 2011.

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

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

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

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre:
Avenue Marnix 17,

B-1000 Brussels © 2011 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 16020:2011: ESIST EN 16020:2011

EN 16020:2011 (E) 2 Contents Page Foreword ..............................................................................................................................................................31Scope ......................................................................................................................................................42Normative references ............................................................................................................................43Terms and definitions ...........................................................................................................................44Explosion Diverters ...............................................................................................................................54.1General ....................................................................................................................................................54.2Special requirements to explosion diverters ......................................................................................65Verification of efficacy and mechanical integrity of the diverter by experimental testing ............65.1General ....................................................................................................................................................65.2Test Modules ..........................................................................................................................................76Test Report .......................................................................................................................................... 127Information for use ............................................................................................................................. 138Marking ................................................................................................................................................ 14Annex A (normative)

Constructional design of pipe-in-pipe diverters ....................................................... 15Annex B (informative)

Explosion diverter types ........................................................................................... 17B.1Single pipe-in-pipe explosion diverter.............................................................................................. 17B.2Multiple pipe-in-pipe explosion diverter ........................................................................................... 17B.3Combination systems ........................................................................................................................ 18B.4Diverter with integrated internal closure (flap) ................................................................................ 19Annex ZA (informative)

Relationship between this European Standard and the Essential Requirements of EU Directive 94/9/EC ............................................................................................. 20Bibliography ..................................................................................................................................................... 21 SIST EN 16020:2011

EN 16020:2011 (E) 3 Foreword This document (EN 16020:2011) 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 January 2012, and conflicting national standards shall be withdrawn at the latest by January 2012. 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 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. SIST EN 16020:2011

EN 16020:2011 (E) 4 1 Scope An explosion diverter is used to divert explosions propagating through ducts, thus preventing flame jet ignition and pressure piling in connected protected enclosures. It will reduce the risk of flame transmission. This European Standard describes the basic design of a pipe-in-pipe diverter and specifies the testing requirements and the application of explosion diverters.

This European Standard covers:  a test method for assessing the efficacy of explosion diverters;  design rules for a type of pipe-in-pipe diverter;  demands to venting device on diverter;  installation requirements;  maintenance requirements;  marking. This European Standard considers dust/air explosive atmospheres only. 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. EN 13237, Potentially explosive atmospheres — Terms and definitions for equipment and protective systems intended for use in potentially explosive atmospheres 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 14460:2006, Explosion resistant equipment EN 14491: Dust explosion venting protective systems EN 14797, Explosion venting devices EN 15089:2009, Explosion isolation systems EN ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories

(ISO/IEC 17025:2005) 3 Terms and definitions For the purposes of this document, the terms and definitions given in EN 13237, EN 14797, EN 14491 , EN 15089:2009 and the following apply. SIST EN 16020:2011

EN 16020:2011 (E) 5 3.1 explosion venting device part of the explosion diverter which opens under explosion conditions in a controlled manner 3.2 explosion diverter passive mechanical device typically installed in a duct preventing flame jet ignition, pressure piling and reducing the probability of flame transmission into connected equipment 3.3 flame velocity Sf velocity of a flame front relative to a fixed reference point [EN 15089:2009, 3.14] 3.4 pressure piling condition during deflagration in which pressure increases in the unreacted medium ahead of the flame front as a result of the deflagration 3.5 flame jet ignition ignition of unreacted pre-compressed and turbulent medium in an enclosure by a flame with a large surface area and high energy 3.6 installation distance distance between the vessel and the connecting flange of the diverter 3.7 optimum explosion pressure popt explosion pressure in the vented or unvented vessel of the primary explosion which causes maximum flame velocity in the pipe at the inlet of the connected vessel, without diverter 4 Explosion Diverters 4.1 General Explosion diverters are inline passive protective systems, installed in processes involving dust. They respond to and by means of internal explosion pressure in the duct in which they are installed. The most common design of explosion diverters can be described as pipe in pipe arrangements (see Figure 1) causing a change of flow direction and fitted with an explosion venting device (see Figure 1 a) and Annex A). This type of diverter will typically have an inner inlet pipe and an outer outlet pipe. Other types of explosion diverters are described in Annex B. In most cases, the installation of explosion diverters is closely related to pre-arranged planning and engineering. Subsequently, the installation will be executed as per agreed-upon general arrangement and detail drawings of the system of which the explosion diverter becomes a part. In the case of an explosion propagating through a duct, the venting device opens and diverts flame and pressure. This shall be done into a safe area (see Figure 1 b)). Explosion diverters shall ensure as a minimum that pressure piling and flame jet ignition are prevented beyond the diverter. They cannot completely stop the flame and pressure propagation under all conditions. SIST EN 16020:2011

EN 16020:2011 (E) 6 a) closed b)openFigure 1 — Example of a pipe-in-pipe explosion diverter 4.2 Special requirements to explosion diverters 4.2.1 Explosion venting device Venting devices shall comply with EN 14797 with the exception of the determination of the efficiency of the device. In addition, tests according to Clause 5 shall be undertaken to demonstrate their suitability for intended use on explosion diverters. 4.2.2 Mechanical integrity Depending on the intended use, the loads caused by internal explosions will to a great extent depend on equipment connected to the device (vessel size, length of interconnecting pipes) and explosion properties of the dust (intended range of KSt, pmax). Any part of an explosion diverter not designed to rupture shall be constructed such that it can withstand the loads imposed by any internal explosion that can be expected in accordance with its intended use, without rupturing. The construction can be either explosion-pressure resistant or explosion-pressure shock-resistant (see EN 14460). If parts of or the entire explosion venting device detach during the explosion, the explosion diverter shall include a restraining arrangement e.g. a cage. The restraining arrangement is an integral part of the explosion diverter. The requirements pertaining to mechanical integrity include the elements of the restraining arrangement. 5 Verification of efficacy and mechanical integrity of the diverter by experimental testing 5.1 General The testing shall reflect the intended use. As a minimum the following information is necessary prior to testing: SIST EN 16020:2011

EN 16020:2011 (E) 7  a general type description;  intended use;  installation and operating instructions (maximum allowable length of the pipes between explosion diverter and interconnected vessels and the presence of bends/pipe restrictions, location and position of the explosion diverter);  part list;  design and manufacturing drawings and layouts of parts etc.;  results of design calculations made, examinations carried out, test reports;  ambient and process conditions;  dust type (KSt, pmax, metal dust yes/no);  explosion resistance of the device;  static activation pressure (pstat) of the venting device;  maximum explosion pressure in the connected vessels. The smallest and largest size for devices with geometrical similarity (with respect to the material specifications, welding specifications and wall thickness) shall be tested. If the diameter ratio of largest to smallest size exceeds 5, an intermediate size shall be tested. 5.2 Test Modules 5.2.1 General Two modules are available for experimental testing, The modules are referenced to as Module A and Module B. The mechanical integrity and explosion resistance of the diverter is tested in either of these two modules. The test pressure required to prove the mechanical integrity and explosion resistance according to the intended use is material dependant and shall be according to EN 14460:2006, 6.3. Permanent deformation of the diverter body is allowed provided it does not fail in its function and will not give rise to dangerous effects to the surrounding. If permanent deformation is observed, the explosion resistance shall be documented as the explosion pressure shock resistance according to EN 14460. 5.2.2 Module A: Mechanical integrity testing 5.2.2.1 General Module A (mechanical integrity testing only) is used for testing:  pipe-in-pipe diverters according to Annex A;  any other type of diverter which was previously tested and approved according to Module B but which did undergo changes which can affect the mechanical integrity and explosion resistance of the diverter. Changes to the geometry for instance will require retesting according to Module B. Furthermore, modification of the venting device or the introduction of a restraining cage needs testing according to Module B. 5.2.2.2 Test set-up The explosion diverter shall be tested with a test rig as shown in Figure 2. SIST EN 16020:2011

EN 16020:2011 (E) 8
Key 1,2,3 pressure transducer (Pt) 4
explosion diverter body (ED) 5
explosion diverter venting device L

installation distance Figure 2 — Test arrangement for mechanical and explosion resistance testing The dimensions of the pipe (length and diameter), the pipe arrangement (e.g. horizontal/vertical), the volume of the test vessel, the maximum reduced explosion pressure in the test vessel and the explosion characteristics of the explosive atmosphere shall reflect the intended use of the diverter (see 5.1). The length to diameter ratio of the vessel shall be equal to or smaller than 2,5 and the pipe volume up to the explosion diverter shall be smaller than the volume of the vessel. The explosion pressure generated within the diverter shall reflect the maximum allowable explosion pressure according to the intended use of the diverter. If the intended use includes scenarios in which the explosion can propagate in both directions, the testing shall be repeated with the diverter reversed such that the outlet now becomes the inlet. 5.2.2.3 Measuring technique The following parameter shall be measured:  Pressure The explosion pressure shall be measured by installing transducers in the explosion enclosure, the diverter and the interconnecting duct (see Figure 2). The pressure transducer shall have a sufficient short response time. 5.2.2.4 Testing method Sufficient explosive dust shall be injected in the test vessel to generate an explosive dust/air mixture in the duct to support flame propagation into the diverter. The generation of the dust cloud inside the test vessel shall be carried out according to EN 14034-1 and EN 14034-2. SIST EN 16020:2011

EN 16020:2011 (E) 9 Testing shall be carried out at maximum pred, KSt and longest installation distance at which the maximum allowable explosion pressure as per the intended use of the diverter is reached. Calibration tests shall be carried out without explosion diverter in the test rig according to Figure 2 to define the test parameters (dust concentration, ignition delay time, venting area) necessary to achieve the optimum explosion pressures (popt) according to the intended use and flame transmission and acceleration throughout the pipe (worst case condition). Dust injection in the duct can be necessary. a) Number of tests Only 1 test is required for mechanical integrity testing. b) Evaluation of test The mechanical integrity testing is successful if the diverter has withstood the intended explosion pressure and did not generate any flying parts. 5.2.3 Module B: Functional testing 5.2.3.1 General Module B (functional testing) shall a

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