Design of fans working in potentially explosive atmospheres

1.1   This European Standard specifies the constructional requirements for fans constructed to Group II G (of explosion groups IIA, IIB and hydrogen) categories 1, 2 and 3, and Group II D categories 2 and 3, intended for use in explosive atmospheres.
NOTE   Operation conditions for the different categories of fans used in this European Standard are defined in Clause 4.
1.2   This European Standard does not apply to group I fans (fans for mining), cooling fans or impellers on rotating electrical machines, cooling fans or impellers on internal combustion engines.
NOTE 1   Requirements for group I fans are given in EN 1710.
NOTE 2   The requirements for electrical parts are covered by references to electrical equipment standards.
1.3   This European Standard specifies requirements for design, construction, testing and marking of complete fan units intended for use in potentially explosive atmospheres in air containing gas, vapour, mist and/or dusts. Such atmospheres may exist inside (the conveyed fluid), outside, or inside and outside of the fan.
1.4   This European Standard is applicable to fans working in the range of ambient atmospheres having absolute pressures ranging from 0,8 bar to 1,1 bar, temperatures ranging from -20 °C to -60 °C, maximum volume fraction of 21 % oxygen content and by the condition at the inlet (pressure ranging from 0,8 bar to 1,1 bar, temperatures ranging from -20 °C to +60 °C) and an aerodynamic energy increase of less than 25 kJ/kg.
NOTE 1   25 kJ/kg is equivalent to 30 kPa at inlet density of 1,2 kg/m³.
NOTE 2   This European Standard may also be helpful for the design, construction, testing and marking of fans intended for use in atmospheres outside the validity range stated above or in cases where other material pairings need to be used. In this case, the ignition risk assessment, ignition protection provided, additional testing (if necessary), manufacturer's marking, technical documentation and instructions to the user, should clearly demonstrate and indicate the equipment's suitability for the conditions the fan may encounter.
NOTE 3   This European Standard does not apply to integral fans of electric motors.
NOTE 4   Where undated references are used in the body of the standard the latest edition applies.

Konstruktion von Ventilatoren für den Einsatz in explosionsgefährdeten Bereichen

1.1   Diese Europäische Norm legt die baulichen Anforderungen an Ventilatoren der Gruppe IIG (der Explosionsgruppen IIA, IIB und Wasserstoff) Kategorien 1, 2 und 3 und Gruppe IID Kategorien 2 und 3 für die Verwendung in explosionsfähigen Atmosphären fest.
ANMERKUNG   Betriebsbedingungen für die verschiedenen Kategorien von Ventilatoren, die von dieser Europäischen Norm erfasst werden, sind in Abschnitt 4 definiert.
1.2   Diese Norm ist nicht anwendbar auf Gruppe-I-Ventilatoren (Ventilatoren für den Bergbau), Kühlgebläse oder Flügelräder für drehende elektrische Maschinen sowie Kühlgebläse oder Flügelräder für Verbrennungsmotoren.
ANMERKUNG 1   Anforderungen an Gruppe-I-Ventilatoren sind in EN 1710 enthalten.
ANMERKUNG 2   Die Anforderungen an elektrische Bauteile werden durch Verweisungen auf Normen für elektrische Geräte behandelt.
1.3   Diese Europäische Norm legt Anforderungen an Konstruktion, Bau, Prüfung und Kennzeichnung kompletter Ventilator-Einheiten fest, die für den Einsatz in explosionsfähiger Atmosphäre, die durch Gase, Dämpfe, Nebel und/oder Staub entsteht, bestimmt sind. Solche Atmosphären können innerhalb (durch das geförderte Fluid), außerhalb, oder innerhalb und außerhalb des Ventilators existieren.
1.4   Diese Europäische Norm gilt für Ventilatoren, die in umgebenden Atmosphären mit einem absoluten Druck von 0,8 bar bis 1,1 bar, Temperaturen von –20 °C bis 60 °C, maximal 21 % Volumenanteil Sauerstoff, und unter den Bedingungen am Eintritt (Druckbereich von 0,8 bar bis 1,1 bar, Temperaturbereich von -20 °C bis +60 °C) bei einer aerodynamischen Energie-Zunahme von weniger als 25 kJ/kg arbeiten.
ANMERKUNG 1   25 kJ/kg entsprechen 30 kPa bei einer Eintrittsdichte von 1,2 kg/m3.
ANMERKUNG 2   Diese Europäische Norm kann auch hilfreich sein für Konstruktion, Bau, Prüfung und Kennzeichnung von Ventilatoren, die für den Einsatz in Atmosphären bestimmt sind, die nicht in den Gültigkeitsbereich dieser Norm fallen, oder in Fällen, in denen andere Werkstoffpaarungen verwendet werden müssen. In diesem Fall sollten die Bewertung des Zündrisikos, der vorgesehene Zündschutz, zusätzliche Prüfung (falls erforderlich), Hersteller-Kennzeichnung, technische Dokumentation und Anweisungen an den Benutzer klar nachweisen, dass die Ventilatoren für die Bedingungen, auf die sie treffen, geeignet sind.
ANMERKUNG 3   Diese Europäische Norm gilt nicht für in Elektromotoren integrierte Ventilatoren.
ANMERKUNG 4   Undatierte Verweisungen im Hauptteil der Norm beziehen sich auf die jeweils neueste Ausgabe.

Conception des ventilateurs pour les atmosphères explosibles

1.1   La présente Norme européenne spécifie les exigences de construction pour les ventilateurs fabriqués selon le Groupe II G (des groupes d'explosion IIA, IIB et hydrogène) des catégories 1, 2 et 3, et selon le Groupe II D catégories 2 et 3, destinés à être utilisés en atmosphères explosibles.
NOTE   Les conditions de fonctionnement des différentes catégories de ventilateurs utilisées dans la présente Norme européenne sont définies à l'Article 4.
1.2   La présente Norme européenne ne s’applique pas aux ventilateurs du groupe I (ventilateurs pour mines), aux ventilateurs de refroidissement ou roues montées sur des machines électriques tournantes, ventilateurs de refroidissement ou roues montées sur des moteurs fixes à combustion interne.
NOTE 1   Les exigences relatives aux ventilateurs du groupe I sont données dans l'EN 1710.
NOTE 2   Les exigences relatives aux parties électriques sont couvertes par des références à des normes relatives aux équipements électriques.
1.3   La présente Norme européenne définit les exigences relatives à la conception, à la construction, aux essais et au marquage de ventilateurs complets destinés à être utilisés en atmosphères explosibles d'air chargé de gaz, de vapeurs, de brouillards et/ou de poussières. Ces atmosphères peuvent également exister à l’intérieur (du fluide transporté), à l'extérieur, ou à l'intérieur et à l'extérieur du ventilateur.
1.4   La présente Norme européenne s'applique aux ventilateurs fonctionnant dans des atmosphères ambiantes avec des pressions absolues allant de 0,8 bar à 1,1 bar, des températures allant de - 20 °C à  60 °C, une teneur en oxygène de 21 % en volume, une condition à l'aspiration (pression allant de 0,8 bar à 1,1 bar, températures allant de -20 °C à +60 °C) et une augmentation d'énergie aérodynamique inférieure à 25 kJ/kg.
NOTE 1   25 kJ/kg sont équivalents à 30 kPa pour une masse volumique à l’entrée de 1,2 kg/m³.
NOTE 2   La présente Norme européenne peut également s’avérer utile pour la conception, la construction, les essais et le marquage des ventilateurs destinés à être utilisés dans des atmosphères n’entrant pas dans la plage de validité indiquée ci-dessus ou dans des cas où le recours à d'autres couples de matériaux s'avère nécessaire. Dans ce cas, il convient que l'évaluation du risque d’inflammation, la protection prévue à cet effet, les essais supplémentaires (si nécessaire), le marquage du fabricant, la documentation technique et les instructions destinées à l’utilisateur démontrent et indiquent clairement que l’appareil est adapté aux conditions qu’un ventilateur peut rencontrer.
NOTE 3   La présente Norme européenne ne s’applique pas aux ventilateurs intégrés de moteurs électriques.
NOTE 4   Lorsque des références non datées sont utilisées dans le corps de la norme, la dernière édition de la publication s'applique.

Načrtovanje ventilatorjev za delovanje v potencialno eksplozivnih atmosferah

1.1 Ta evropski standard določa konstrukcijske zahteve za ventilatorje, izdelane za skupino II G (v okviru eksplozijskih skupin II A, II B in vodika) kategorij 1, 2 in 3 ter skupino II D kategorij 2 in 3, ki so namenjeni za uporabo v eksplozivnih atmosferah.
OPOMBA: Pogoji delovanja za različne kategorije ventilatorjev, ki se uporabljajo v tem evropskem standardu, so določeni v točki 4.
1.2 Ta evropski standard se ne uporablja za ventilatorje skupine I (ventilatorji za uporabo v rudarstvu), hladilne ventilatorje ali rotorje pri rotacijskih električnih strojih in hladilne ventilatorje ali rotorje pri motorjih z notranjim izgorevanjem.
OPOMBA 1: Zahteve za ventilatorje skupine I so podane v standardu EN 1710.
OPOMBA 2: Zahteve za električne dele so zajete s sklici na standarde za električno opremo.
1.3 Ta evropski standard določa zahteve za načrtovanje, izdelavo, preskušanje in označevanje zaključenih ventilatorskih enot, namenjenih za uporabo v potencialno eksplozivnih atmosferah plinov, hlapov, meglic in/ali prahu v zraku. Take atmosfere lahko obstajajo znotraj (prevajana tekočina), zunaj ali znotraj in zunaj ventilatorja.
1.4 Ta evropski standard se uporablja za ventilatorje, ki delujejo v okoljskih atmosferah z vrednostmi absolutnega tlaka od 0,8 bara do 1,1 bara, temperaturami od –20 °C do –60 °C, največjim prostorninskim deležem vsebnosti kisika 21 % ter pri vhodnih pogojih (tlak od 0,8 bara do 1,1 bara, temperature od –20 °C do 60 °C) in porastu aerodinamične energije manj kot 25 kJ/kg.
OPOMBA 1: 25 kJ/kg je enako 30 kPa pri vhodni gostoti 1,2 kg/m³.
OPOMBA 2: Ta evropski standard je lahko uporaben tudi pri načrtovanju, izdelavi, preskušanju in označevanju ventilatorjev za uporabo v atmosferah z vrednostmi zunaj zgoraj navedenega validativnega obsega ali v primerih potrebne uporabe drugih vezav materialov. V tem primeru mora biti ustreznost opreme za potencialne pogoje delovanja ventilatorja jasno izražena in prikazana z oceno tveganja za vžig, razpoložljivo zaščito pred vžigom, dodatnim preskušanjem (po potrebi), označbami proizvajalca, tehnično dokumentacijo in navodili za uporabnika.
OPOMBA 3: Ta evropski standard se ne uporablja za ventilatorje, ki so sestavni deli elektromotorjev.
OPOMBA 4: V primeru uporabe nedatiranih sklicevanj v besedilu standarda se uporablja najnovejša izdaja.

General Information

Status
Published
Public Enquiry End Date
29-Apr-2014
Publication Date
21-Mar-2017
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
24-Jan-2017
Due Date
31-Mar-2017
Completion Date
22-Mar-2017

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Konstruktion von Ventilatoren für den Einsatz in explosionsgefährdeten BereichenConception des ventilateurs pour les atmosphères explosiblesDesign of fans working in potentially explosive atmospheres29.260.20Electrical apparatus for explosive atmospheres23.120QDSUDYHVentilators. Fans. Air-conditionersICS:Ta slovenski standard je istoveten z:EN 14986:2017SIST EN 14986:2017en,fr,de01-april-2017SIST EN 14986:2017SLOVENSKI

STANDARDSIST EN 14986:20071DGRPHãþD
SIST EN 14986:2017
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 14986
January
t r s y ICS
t uä s t r Supersedes EN
s v { z xã t r r yEnglish Version

Design of fans working in potentially explosive atmospheres Conception des ventilateurs pour les atmosphères explosibles

Konstruktion von Ventilatoren für den Einsatz in explosionsgefährdeten Atmosphären This European Standard was approved by CEN on

u r October
t r s xä

egulations which stipulate the conditions for giving this European Standard the status of a national standard without any alterationä Upætoædate lists and bibliographical references concerning such national standards may be obtained on application to the CENæCENELEC Management Centre or to any CEN memberä

translation under the responsibility of a CEN member into its own language and notified to the CENæCENELEC Management Centre has the same status as the official versionsä

CEN members are the national standards bodies of Austriaá Belgiumá Bulgariaá Croatiaá Cyprusá Czech Republicá Denmarká Estoniaá Finlandá Former Yugoslav Republic of Macedoniaá Franceá Germanyá Greeceá Hungaryá Icelandá Irelandá Italyá Latviaá Lithuaniaá Luxembourgá Maltaá Netherlandsá Norwayá Polandá Portugalá Romaniaá Serbiaá Slovakiaá Sloveniaá Spainá Swedená Switzerlandá Turkey and United Kingdomä

EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre:
Avenue Marnix 17,
B-1000 Brussels

t r s y CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Membersä Refä Noä EN

s v { z xã t r s y ESIST EN 14986:2017

EN 14986:2017 (E) 2 Contents Page European foreword ....................................................................................................................................................... 4 Introduction .................................................................................................................................................................... 5 1 Scope .................................................................................................................................................................... 6 2 Normative references .................................................................................................................................... 7 3 Terms and definitions ................................................................................................................................... 7 4 Requirements for all fans ............................................................................................................................. 8 4.1 Ignition hazard assessment ......................................................................................................................... 8 4.1.1 General ................................................................................................................................................................ 8 4.1.2 Normal operating conditions ...................................................................................................................... 8 4.1.3 Expected malfunction .................................................................................................................................... 8 4.1.4 Rare malfunction ............................................................................................................................................. 8 4.2 Assignment of categories ............................................................................................................................. 8 4.3 Temperatures ................................................................................................................................................... 9 4.3.1 General ................................................................................................................................................................ 9 4.3.2 Maximum surface temperature ................................................................................................................. 9 4.3.3 Temperature of the conveyed atmosphere (flammable or not) ................................................. 10 4.4 Mechanical design criteria ........................................................................................................................ 10 4.4.1 General ............................................................................................................................................................. 10 4.4.2 Clearance between rotating elements and the fan casing ............................................................. 10 4.5 Casing ............................................................................................................................................................... 11 4.5.1 General ............................................................................................................................................................. 11 4.5.2 Gas tightness .................................................................................................................................................. 11 4.6 Impellers ......................................................................................................................................................... 11 4.7 Materials for rotating and stationary parts of fans.......................................................................... 11 4.7.1 General ............................................................................................................................................................. 11 4.7.2 Permissible material pairings ................................................................................................................. 12 4.8 Linings and tip extensions ........................................................................................................................ 22 4.9 Vibration ......................................................................................................................................................... 22 4.10 Earthing conducting parts ........................................................................................................................ 23 4.11 Electrostatic charges ................................................................................................................................... 23 4.12 Electrical equipment ................................................................................................................................... 23 4.13 Prevention of deposits inside the fan ................................................................................................... 23 4.14 Shaft seals ....................................................................................................................................................... 24 4.15 Bearings ........................................................................................................................................................... 24 4.16 Power transmission systems ................................................................................................................... 24 4.17 Clutches and couplings ............................................................................................................................... 24 4.18 Brakes and braking systems .................................................................................................................... 24 4.19 Impeller-shaft attachment ........................................................................................................................ 24 4.20 Corrosion of fan components ................................................................................................................... 28 4.21 Fire resistance ............................................................................................................................................... 28 4.22 Protection against foreign particles ...................................................................................................... 28 5 Additional requirements for category 2 .............................................................................................. 28 5.1 General ............................................................................................................................................................. 28 5.2 Impeller-shaft attachment ........................................................................................................................ 28 5.3 Vibration ......................................................................................................................................................... 29 SIST EN 14986:2017

EN 14986:2017 (E) 3 5.4 Material pairings ........................................................................................................................................... 29 6 Category 1 fans for specific use with a gaseous explosive atmosphere as a conveyed atmosphere (flammable or not) .............................................................................................................. 29 6.1 General requirements ................................................................................................................................. 29 6.2 Flame arresters ............................................................................................................................................. 29 6.2.1 General ............................................................................................................................................................. 29 6.2.2 Stabilized burning ........................................................................................................................................ 29 6.3 Casings .............................................................................................................................................................. 30 6.3.1 General ............................................................................................................................................................. 30 6.3.2 Gas tightness ................................................................................................................................................... 30 7 Information for use ...................................................................................................................................... 30 7.1 General ............................................................................................................................................................. 30 7.2 Accompanying documentation ................................................................................................................ 30 7.3 Markings .......................................................................................................................................................... 32 Annex A (normative)

Additional requirements for category 1 G fans .................................................... 33 A.1 General ............................................................................................................................................................. 33 A.2 Flame transmission test ............................................................................................................................. 33 A.3 Pressure test ................................................................................................................................................... 34 Annex B (informative)

Classification of requirements for the different categories .......................... 35 Annex C (informative)

Checklist for verification of the safety requirements and/or protective measures .................................................................................................................................... 39 C.1 General ............................................................................................................................................................. 39 C.2 All categories .................................................................................................................................................. 39 C.3 Category 2 – Gas and dust .......................................................................................................................... 40 C.4 Category 1 – Gas ............................................................................................................................................ 40 Annex D (informative)

Examples of types of fans showing ignition minimizing features .............. 41 Annex E (normative)

List of significant hazards ............................................................................................. 46 Annex ZA (informative)

Relationship between this European

Standard and the Essential Requirements of EU Directive 2014/34/EU........................................................................................ 50 Bibliography ................................................................................................................................................................. 51

SIST EN 14986:2017

EN 14986:2017 (E) 4 European foreword This document (EN 14986:2017) 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 document supersedes EN 14986:2007. 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 July 2017, and conflicting national standards shall be withdrawn at the latest by July 2017. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN 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 2014/34/EU. 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 organisations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. SIST EN 14986:2017

EN 14986:2017 (E) 5 Introduction This European Standard is a type C standard as stated in EN ISO 12100. The machinery concerned and the extent to which hazards, hazardous situations and events are covered and indicated in the scope of this European Standard. When provisions of this type C standard are different from those, which are stated in type A or B standards, the provisions of this type C standard take precedence over the provisions of the other standards, for machines that have been designed and built according to the provisions of this type C standard. SIST EN 14986:2017

EN 14986:2017 (E) 6 1 Scope 1.1 This European Standard specifies the constructional requirements for fans constructed to Group II G (of explosion groups IIA, IIB and hydrogen) categories 1, 2 and 3, and Group II D categories 2 and 3, intended for use in explosive atmospheres. NOTE 1 Operation conditions for the different categories of fans used in this European Standard are defined in Clause 4. NOTE 2 Technical requirements for category 1 D fans are not given in this document. Where explosive dust atmospheres are regularly conveyed, explosion protection measures as described in EN 1127–1 are required if this specific us is needed. 1.2 This European Standard does not apply to group I fans (fans for mining), cooling fans or impellers on rotating electrical machines, cooling fans or impellers on internal combustion engines. NOTE 1 Requirements for group I fans are given in EN 1710. NOTE 2 The requirements for electrical parts are covered by references to electrical equipment standards. 1.3 This European Standard specifies requirements for design, construction, testing and marking of complete fan units intended for use in potentially explosive atmospheres in air containing gas, vapour, mist and/or dusts. Such atmospheres may exist inside (the conveyed atmosphere (flammable or not)), outside, or inside and outside of the fan. 1.4 This European Standard is applicable to fans working in ambient atmospheres and with normal atmospheric conditions at the inlet, having — absolute pressures ranging from 0,8 bar to 1,1 bar, — and temperatures ranging from

« t r °C to +60 °C, — and maximum volume fraction of 21 % oxygen content, — and an aerodynamic energy increase of less than 25 kJ/kg. NOTE 1 25 kJ/kg is equivalent to 30 kPa at inlet density of 1,2 kg/m3. This European Standard may also be helpful for the design, construction, testing and marking of fans intended for use in atmospheres outside the validity range stated above or in cases where other material pairings need to be used. In this case, the ignition risk assessment, ignition protection provided, additional testing (if necessary), manufacturer's marking, technical documentation and instructions to the user, should clearly demonstrate and indicate the equipment's suitability for the conditions the fan may encounter. This European Standard should not apply to integral fans as a part of Diesel engines, vehicles or electric motors. NOTE 2 Where undated references are used in the body of the standard the latest edition applies. SIST EN 14986:2017

EN 14986:2017 (E) 7 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 1127-1:2011, Explosive atmospheres - Explosion prevention and protection - Part 1: Basic concepts and methodology EN ISO 80079-36:2016, Explosive atmospheres - Part 36: Non-electrical equipment for explosive atmospheres - Basic method and requirements (ISO 80079-36:2016) EN ISO 80079-37:2016, Explosive atmospheres - Part 37: Non-electrical equipment for explosive atmospheres - Non-electrical type of protection constructional safety ''c'', control of ignition sources ''b'', liquid immersion ''k'' (ISO 80079-37:2016) EN 60079-0, Explosive atmospheres - Part 0: Equipment - General requirements EN ISO 5801, Industrial fans - Performance testing using standardized airways (ISO 5801) EN ISO 11925-2, Reaction to fire tests - Ignitability of products subjected to direct impingement of flame - Part 2: Single-flame source test (ISO 11925-2) EN ISO 12100, Safety of machinery - General principles for design - Risk assessment and risk reduction (ISO 12100) 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) EN ISO 13349:2010, Fans - Vocabulary and definitions of categories (ISO 13349:2010) ISO 14694:2003, Industrial fans — Specifications for balance quality and vibration levels ISO 14694:2003/AMD1, Industrial fans — Specifications for balance quality and vibration levels 3 Terms and definitions For the purposes of this document, the terms and definitions given in EN 1127-1:2011, EN ISO 80079-36:2016 and the following apply. 3.1 externally mounted flame arrester flame arrester consisting of a flame arrester housing and flame arrester elements mounted as a separate equipment on the fan 3.2 integrated flame arrester flame arrester consisting of a flame arrester housing and flame arrester elements where the flame arrester housing is part of the fan housing 3.3 contact diameter diameter of a rotating part at the point where it can contact a stationary part SIST EN 14986:2017

EN 14986:2017 (E) 8 4 Requirements for all fans 4.1 Ignition hazard assessment 4.1.1 General A list of hazards considered is given in Annex D. These include hazards inside and outside the fan. Where additional hazards could occur an ignition hazard assessment according to EN ISO 80079-36 shall be carried out. For the purposes of fans made according to this European Standard the following operational conditions shall be used as a basis for the ignition hazard assessment and for the assignment of a fan to a particular category. Release of flammable material shall be considered in the ignition hazard assessment for the outside of the fan, see 4.3. 4.1.2 Normal operating conditions Normal operating conditions shall be considered to occur in situations where the fan performs its intended use within its design parameters. This includes conditions during start up and shut down. (See also EN ISO 12100.) For the purposes of fans made according to this European Standard failures (such as a breakdown of seals, flange gaskets or releases of substances caused by accidents) which involve repair or shut-down are not considered to be part of normal operation. 4.1.3 Expected malfunction An expected malfunction shall be considered to be a failure or fault in a fan which normally occurs in practice. In addition an expected malfunction shall be considered to occur when a fan or its components do not perform their intended functions. For the purposes of fans made according to this European Standard this can happen for a variety of reasons, including: a) variation in the properties or dimensions of the fan assembly (e.g. warping of the casing); b) disturbance to or failure of the power supply or other services; c) unnoticed long time operation with defective bearing and leading to contact between impeller and housing; d) release of the impeller blade by vibrations over an extended period. 4.1.4 Rare malfunction A rare malfunction is a type of malfunction which is known to happen but only in rare instances. Two independent expected malfunctions which, separately, would not create an ignition hazard but which, in combination, do create an ignition hazard, are regarded as a single rare malfunction. 4.2 Assignment of categories A fan may have a different category for the inside and outside. Fans which may be used both to convey an explosive gas, vapour, mist or dust atmosphere and/or are located in an explosive gas, vapour, mist or dust atmosphere are assigned categories internally and externally depending on the likelihood of them acting as an effective ignition source. SIST EN 14986:2017

EN 14986:2017 (E) 9 Category 3 fans shall not create an effective ignition source in normal operation, see 4.1.2. Category 2 fans shall meet Category 3 fans requirements, and in addition not create an effective ignition source with expected malfunctions, see 4.1.3. Category 1 fans shall meet Category 2 fans requirements, and in addition not create an effective ignition source with rare malfunctions, see 4.1.4. Fans, especially their shaft seals and flexible connections at the inlet and outlet, may not be absolutely gas tight, and connected ducts may not be leak proof. The hazardous atmosphere may leak either from the inside of the fan into the adjacent environment, or from a hazardous environment around a fan, and into the fan casing through a leakage path e.g. a shaft seal when this is below atmospheric pressure. Therefore the manufacturer shall consider these aspects in the ignition hazard assessment. The manufacturer shall give information about the possible leakage rates of the fan in the information for use. Where the leakage rates are not known the manufacturer shall construct the fan so that there is no more than one category difference between the inside and the outside. Where the fan has an open inlet and/or outlet (installation modes A, B, C according to EN ISO 13349) the inside and the outside of the fan shall have the same category. 4.3 Temperatures 4.3.1 General Both the temperature of potentially hot surfaces and the temperature of the conveyed atmosphere (flammable or not) and/or of the atmosphere surrounding the fan shall be considered. 4.3.2 Maximum surface temperature The maximum surface temperature of the fan characterizes the hottest part of the equipment that can come in contact with the explosive atmosphere or the maximum temperature of the conveyed atmosphere (flammable or not) which can act as an ignition source. The maximum surface temperatures of both the inside and outside parts of the fan that can come in contact with the explosive atmosphere shall be determined in accordance with EN ISO 80079-36. In addition to that, the maximum surface temperature marked for the inside of the fan shall be the greater of either: — the maximum surface temperature determined in accordance with EN ISO 80079-36 including the appropriate safety margins for the different categories, or — the maximum temperature of the conveyed atmosphere (flammable or not) at the outlet with a safety margin of 20 % (with temperatures measured in °C). These temperatures are determined considering the highest inlet temperature specified in 4.3.3. NOTE This safety margin of 20 % has been chosen because of the enhanced ignition risk at higher gas temperatures. The maximum surface temperature of the equipment is used – after the application of the above safety margins – for marking of the equipment with a defined temperature, a temperature class of the equipment or an appropriate explosive atmosphere. EXAMPLE A fan with the following parameters: The maximum surface temperature of the inside, measured according to EN ISO 80079-36 with the appropriate safety margin is 90 °C, the temperature of the conveyed atmosphere (flammable or not) measured at the outlet is 80 °C for an inlet temperature of 60 °C. With a 20 % safety margin the maximum outlet temperature is 96 °C. Therefore the maximum temperature marked for the inside of the fan is 96 °C. SIST EN 14986:2017

EN 14986:2017 (E) 10 4.3.3 Temperature of the conveyed atmosphere (flammable or not) While it is only the ambient and the inlet temperature which is generally known by the user, it is the normally higher outlet temperature which determines the suitability of the fan for the intended use. As well as temperature increases during normal service, extraordinary temperature increases shall be considered. In the absence of detailed information from the end user on expected fault conditions and maximum and minimum flow, pressure rise and density, the fan manufacturer shall ensure that the appropriate temperature limits are maintained between - 10 % or + 20 % of nominal gas flow, and at maximum and minimum expected densities. Generally maximum temperature rise will occur at minimum flow and maximum density. For variable speed fans the calculation shall be carried out at maximum fan speed and/or the speed which gives maximum fluid outlet temperature. For fans with motor mounted in conveyed atmosphere (flammable or not) consideration shall be given to the heating effect from the motor. The manufacturer's instructions shall include the minimum and maximum air flow rates which are required to maintain the temperature rating. The manufacturer shall measure or calculate the maximum gas temperature for an inlet gas temperature of 60 °C within the gas flow limits or - 10 % to 20 % of nominal gas flow. Where the maximum inlet temperature is below 60 °C, the above calculation shall be made with this lower maximum temperature and the manufacturer shall mark the fan appropriately. Electric motors and other temperature sensitive components shall receive special attention as they generally are designed for a maximum ambient temperature of +40 °C. 4.4 Mechanical design criteria 4.4.1 General Fans for operation in potentially explosive atmospheres shall be of rigid design. This requirement is considered as fulfilled for casings, supporting structures, guards, protective devices and other external parts if the deformation resulting from an impact test at the most vulnerable point is so small that the moving parts do not come into contact with the casing. The test shall be carried out in accordance with EN ISO 80079-36. NOTE Foreseeable causes of reducing the clearances between the casing and the moving parts include distortion of the casing caused by connection to ductwork with no flexible joints, or by damage to the casing during installation. Reduction of the clearance is also possible if the fan is installed with inlet ductwork and the pressure drops below atmospheric when the inlet is closed. All impellers, bearings, pulleys, cooling disks etc. shall be securely fixed in position. This requirement shall not apply to the bearings incorporated within electric motors which shall be subject to the requirements specified in EN 60079-0. The manufacturer shall specify the maximum forces and torques i

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