SIST EN 14986:2007
(Main)Design of fans working in potentially explosive atmospheres
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 an aerodynamic energy increase of less than 25 kJ/kg.
NOTE 1 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 2 This European Standard does not apply to integral fans of electric motors.
NOTE 3 Where undated r
Konstruktion von Ventilatoren für den Einsatz in explosionsgefährdeten Bereichen
Diese Norm legt die baulichen Anforderungen an Ventilatoren der Gruppe II G Kategorien 1, 2 und 3, und Gruppe II D Kategorien 2 und 3 für die Verwendung in explosionsfähigen Atmosphären fest.
Betriebsbedingungen für die verschiedenen Kategorien von Ventilatoren, die von dieser Norm erfasst werden, sind in Abschnitt 4 definiert.
Diese Norm ist nicht anwendbar auf Ventilatoren für die Verwendung im Zusammenhang mit Gasen der Gruppe II C, die im Anhang zu EN 50014 verzeichnet sind.
Diese Norm ist nicht anwendbar auf Gruppe I Ventilatoren (Ventilatoren für den Bergbau), Kühlgebläse oder Flügelräder für drehende elektrische Maschinen, Kühlgebläse oder Flügelräder für Verbrennungsmotoren .
ANMERKUNG 1 Anforderung an Gruppe I Ventilatoren sind in EN 1710 enthalten.
Diese 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, außerhalb, oder innerhalb und außerhalb des Ventilators existieren.
Diese 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 und maximal 21 % Volumenanteil Sauerstoff bei einer aerodynamischen Energie-Zunahme von weniger als 25 kJ/kg arbeiten.
ANMERKUNG 2 Diese 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. In diesem Fall sollte durch Bewertung des Zündrisikos, der vorgeschlagenen Zündschutzart, der zusätzlichen Prüfung (falls erforderlich), der Hersteller-Kennzeichnung, der technischen Dokumentation und Betriebsanweisungen dem Benutzer die Eignung der Ventilatoren eindeutig dargestellt und nachgewiesen werden.
Conception des ventilateurs pour les atmospheres explosibles
Načrtovanje ventilatorjev za delovanje v potencialno eksplozivnih atmosferah
General Information
Relations
Standards Content (Sample)
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 atmospheres explosiblesDesign of fans working in potentially explosive atmospheres23.120QDSUDYHVentilators. Fans. Air-conditioners13.230Varstvo pred eksplozijoExplosion protectionICS:Ta slovenski standard je istoveten z:EN 14986:2007SIST EN 14986:2007en,fr,de01-julij-2007SIST EN 14986:2007SLOVENSKI
STANDARD
SIST EN 14986:2007
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 14986February 2007ICS 23.120; 29.260.20 English VersionDesign of fans working in potentially explosive atmospheresConception des ventilateurs pour les atmosphèresexplosiblesKonstruktion von Ventilatoren für den Einsatz inexplosionsgefährdeten BereichenThis European Standard was approved by CEN on 13 January 2007.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: rue de Stassart, 36
B-1050 Brussels© 2007 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 14986:2007: ESIST EN 14986:2007
EN 14986:2007 (E) 2 Contents Page Foreword.3 Introduction.4 1 Scope.5 2 Normative references.5 3 Terms and definitions.6 4 Requirements for all fans.6 5 Additional requirements for category 2 fans.16 6 Category 1 fans for use with gas as the conveyed fluid.17 7 Information for use.18 Annex A (normative)
Additional requirements for category 1 G fans.21 Annex B (informative)
Checklist for verification of the safety requirements and/or protective measures24 Annex C (informative)
Examples of types of fans showing ignition minimising features.26 Annex D (normative)
List of significant hazards.31 Annex ZA (informative)
Relationship between this European Standard and the Essential Requirements
of EU Directive 94/9/EC.34 Bibliography.35
Figures Figure A.1 — Test apparatus for the flame transmission test.22 Figure C.1 — Axial fan with fixed pitch blades and ducted inlet for categories 2 and 3.26 Figure C.2 — Axial fan with variable pitch in-motion ducted inlet-box arrangement.27 Figure C.3 — Mixed flow belt driven ducted fan.28 Figure C.4 — Centrifugal fan - ducted arrangement.29 Figure C.5 — Typical fan drive belt guard details.30 Tables
Page Table 1 — Permissible material pairings for gas explosion groups IIA and IIB.11 Table 2 — Permissible material pairings for gas mixtures containing hydrogen.13 Table 3 — Minimum thickness of linings.13 Table D.1 — Identification of hazards and required countermeasures.31
SIST EN 14986:2007
EN 14986:2007 (E) 3 Foreword This document (EN 14986:2007) 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 August 2007, and conflicting national standards shall be withdrawn at the latest by August 2007. 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 94/9/EC. For relationship with EU Directive 94/9/EC, 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 United Kingdom. SIST EN 14986:2007
EN 14986:2007 (E) 4 Introduction This European Standard is a type C standard as stated in EN ISO 12100-1. 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 14986:2007
EN 14986:2007 (E) 5 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 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 an aerodynamic energy increase of less than 25 kJ/kg. NOTE 1 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 2 This European Standard does not apply to integral fans of electric motors. NOTE 3 Where undated references are used in the body of the standard the latest edition applies. 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 294, Safety of machinery — Safety distance to prevent danger zones being reached by the upper limbs EN 1050, Safety of machinery — Principles for risk assessment EN 1127-1:1997, Explosive atmospheres — Explosion prevention and protection — Part 1: Basic concepts and methodology EN 12874:2001, Flame arresters — Performance requirements, test methods and limits for use EN 13463-1:2001, Non-electrical equipment for potentially explosive atmospheres — Part 1: Basic method and requirements EN 13463-5, Non-electrical equipment intended for use in potentially explosive atmospheres — Part 5: Protection by constructional safety "c" EN 13463-6, Non-electrical equipment for use in potentially explosive atmospheres — Part 6: Protection by control of ignition source "b" SIST EN 14986:2007
EN 14986:2007 (E) 6 EN 50281-1-1, Electrical apparatus for use in the presence of combustible dust — Part 1-1: Electrical apparatus protected by enclosures – Construction and testing EN 60079-0, Electrical apparatus for explosive gas atmospheres — Part 0: General requirements
(IEC 60079-0:2004) EN 60529, Degrees of protection provided by enclosures (IP Code) (IEC 60529:1989) EN ISO 12100-1, Safety of machinery — Basic concepts, general principles for design — Part 1: Basic terminology, methodology (ISO 12100-1:2003) EN ISO 12100-2, Safety of machinery — Basic concepts, general principles for design — Part 2: Technical principles (ISO 12100-2:2003) ISO 12499, Industrial fans — Mechanical safety of fans — Guarding ISO 13349:1999, Industrial fans — Vocabulary and definitions of categories ISO 14694:2003, 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 1127-1:1997, EN 12874:2001 and EN 13463-1:2001 and the following apply. 3.1 externally mounted flame arrester flame arrester with flame arrester housing and flame arrester elements directly mounted as a separate equipment on the fan 3.2 integrated flame arrester flame arrester where flame arrester housing and flame arrester elements are part of the fan 3.3 contact diameter diameter of a rotating part at the point where it can contact a stationary part 4 Requirements for all fans 4.1 General All fans within the scope of this European Standard shall comply with the requirements contained in EN 13463-1 unless otherwise stated in this European Standard. NOTE This European Standard deals only with the prevention of ignition of an explosive atmosphere by the fan. Other safety features will need to be incorporated into the construction to meet the requirements of other EU Directives. For example by incorporating the principles of EN ISO 12100 for preventing mechanical hazards, (e.g. guarding to prevent persons contacting rotating parts, sharp edges). 4.2 Ignition hazard assessment 4.2.1 General A list of hazards which can occur is given in Annex D. Where additional hazards could occur an ignition hazard assessment according to EN 13463-1 shall be carried out. SIST EN 14986:2007
EN 14986:2007 (E) 7 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. 4.2.2 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 12100-1.)
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. 4.2.3 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 of a property or of a dimension of the processed material or of the work piece (e.g. warping of the casing); b) disturbance to or failure of the power supply or other services; c) unnoticed long time operation with defect bearing and leading to contact between impeller and housing; d) release of the impeller by vibrations where the impeller is only pressed on the shaft. 4.2.4 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. 4.3 Assignment to 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 in an explosive gas, vapour, mist or dust atmosphere are assigned to categories depending on the likelihood of them acting as an effective ignition source. Category 3 fans shall not be an effective ignition source in normal operation, see 4.2.2. Category 2 fans shall in addition not be an effective ignition source with expected malfunctions, see 4.2.3. Category 1 fans shall in addition not be an effective ignition source with rare malfunctions, see 4.2.4. 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. SIST EN 14986:2007
EN 14986:2007 (E) 8 Where the fan has an open inlet and/or outlet (installation modes A, B, C according to ISO 13349) the inside and the outside of the fan shall have the same category. 4.4 Temperatures 4.4.1 General Both the temperature of potentially hot surfaces and the temperature of the conveyed fluid and/or of the atmosphere surrounding the fan shall be considered. Special attention is to be paid to the fan-specific increase of temperatures during normal and abnormal service conditions due to gas compression, friction and heat generating components like electric motors. 4.4.2 Maximum surface temperature The maximum surface temperature of the fan characterises the hottest part of the equipment that can come in contact with the explosive atmosphere or the maximum temperature of the conveyed fluid 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 13463-1. 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 13463-1 including the appropriate safety margins for the different categories, or the maximum temperature of the conveyed fluid 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 4.4.3. NOTE This increased safety margin of 20 % has been chosen because of the increased ignition rate 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 13463-1 with the appropriate safety margin is 90 °C, the temperature of the conveyed fluid 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. 4.4.3 Temperature of the conveyed fluid 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 purchaser 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 the maximum motor temperature. This speed shall be included in the information for use. The manufacturer's instructions shall include the minimum and maximum air flow rates which are required to maintain the temperature rating. SIST EN 14986:2007
EN 14986:2007 (E) 9 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 different from 60 °C, the manufacturer shall mark the fan appropriately. NOTE Tests have shown that at gas temperatures above + 60 °C ignition hazards increase considerably. Electric motors and other temperature sensitive components shall receive special attention as they generally are designed for a maximum ambient temperature of + 40 °C. 4.5 Mechanical design criteria 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 13463-1. 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. 4.6 Casing 4.6.1 General The fan casing shall be of a substantially rigid design, to satisfy the mechanical design requirements specified in 4.5. For a fan having a driving motor of more than 11 kW a continuously welded or cast casing is required. 4.6.2 Gas tightness Where the casing is not continuously welded and tested for leaks, the manufacturer shall consider the possibility of leakage in the selection of components and equipment attached to the outside of the fan. NOTE For example where flammable substances are being conveyed in a flanged construction, category 3, equipment is often required outside. The manufacturer shall provide information to the user on possible leakage from the fan if a flammable substance is to be conveyed or is present outside. 4.7 Impellers Impellers shall be of a rigid design and shall be able to withstand a test run at a minimum of 1,15 times the maximum operational rotating speed for at least 60 s without causing an ignition risk, i.e. the impeller shall not contact the casing. A continuously welded fabricated impeller or a cast moulded impeller, both having all elements of appropriate thicknesses and strength to ensure average calculated primary stresses less than 2/3 of the yield stress, shall be deemed to satisfy the requirements for a rigid design without testing. Furthermore impellers shall only produce small deformations relative to the clearance within the design temperature range (see 4.15). SIST EN 14986:2007
EN 14986:2007 (E) 10 4.8 Materials for rotating and stationary parts of fans 4.8.1 General In view of possible friction, which can be expected during normal operation or due to malfunctions or even rare malfunction, potential areas of contact between the rotating elements and fixed components shall be manufactured from materials in which the risk of ignition through friction and friction-impact sparks, hot spots or hot surfaces is minimised. Consideration should be given to the fact that layers of combustible or non-combustible materials may cause increased ignition risks. See Annex C. The critical air gap can be lost for many reasons and it is in most designs difficult to measure or monitor. As fans generally are not supervised continuously, contact between rotating and stationary parts may prevail for relatively long time intervals. Therefore even a seldom or short term exposure to an explosive atmosphere will represent a high risk. Material pairings shall be chosen to minimise this hazard. All alloys except aluminium alloys (sheet or cast) shall contain not more than a mass fraction of 15 % aluminium and shall have a homogenous structure. Paints and coatings shall contain not more than a mass fraction of 10 % aluminium. 4.8.2 Permissible material pairings One of the material pairings given in Table 1 for gas explosion groups IIA and IIB or in Table 2 for hydrogen for the different categories shall be used in the construction of ignition protected fans. The pairings shown are for the stationary rubbing part and the rotating rubbing part. Either material (1) or material (2) may be chosen for the rotation part subject to satisfactory mechanical stress performance over the design life of the fan. For category 1 fans this European Standard requires additional protective measures, thus rotating and stationary parts of fans acceptable for category 2 fans are also suitable for category 1. NOTE Many of the material pairings given in Table 1 can cause ignition of sensitive explosive atmospheres if there is a high degree of friction for a long enough time. These pairings have been chosen as a represent a gradation of the ignition risk for different applications. The other constructional measures detailed in this European Standard are essential to ensure the appropriate level of safety of the fan. SIST EN 14986:2007
EN 14986:2007 (E) 11 Table 1 — Permissible material pairings for gas explosion groups IIA and IIB Category Item Material (1) Material (2) 3 2 and 1 Requirements(see below) Foot-notes1 Leaded brass CuZn39Pb or naval brass CuZn39Sn Carbon or stainless steel or cast ironyes yes 2a) a f 2 Copper Carbon or stainless steel or cast ironyes yes 2a)
3 Tin or lead Carbon or stainless steel or cast ironyes yes 2a), 4 a b 4 Aluminium alloy Aluminium alloy yes yes 1, 2b) c 5 Aluminium alloy Naval brass CuZn39Sn yes yes 1, 2b) c f 6 Aluminium alloy Leaded brass CuZnPb3 / CuZn39Pbyes yes 1, 2b) a c 7 Nickel based alloy Nickel based alloy yes yes 3, 5
8 Stainless steel Stainless steel yes yes 4, 5
9 Any other steel alloy or cast iron Any other steel alloy or cast iron yes yes 5
10 Any steel alloy Brass CuZn37 yes no 2, 5, 8
11 Plastic Plastic yes yes 6 d 12 Plastic Naval brass CuZn39Sn yes yes 2, 6 d 13 Plastic Aluminium alloy yes yes 2, 6 c d 14 Plastic Nickel based alloy or nickel based steel alloy yes yes 3, 6 c d 15 Plastic Leaded brass CuZnPb3 yes yes 2, 6 a d 16 Plastic Any steel alloy or cast iron yes yes 6, 9 d 17 Plastic Stainless steel yes yes 4, 6, 9 d 18 Rubber or rubber coated metal Any steel alloy or cast iron or aluminium alloy yes yes 7, 9 c e 19 Rubber coated metal Rubber coated metal yes yes 7, 9 e Footnotes: a Use of alloys containing lead may be prohibited or limited by national or local authorities if this may not be acceptable from an environmental point of view. b The use of tin may be the only permissible combination when explosive dust is present (see below) in order to fulfil the temperature requirements given in EN 1127-1. It will melt before dangerous hot surface temperatures are reached. On the other hand, a low melting temperature may represent a risk to touch underlying materials. c Aluminium alloys containing approximately 12 % silicon e.g. silumin are appropriate from an anti-sparking and corrosion viewpoint
because the alloy is brittle and breaks on contact and thus prevents rubbing. d Where plastic is chosen, it should be noted that not all grades are automatically permissible, as they have a low heat conductivity leading relatively easily to hot surfaces. It should be noted that the mechanical properties of plastic may limit its use for impellers (see 4.12). e Rubbers may be natural or synthetic. The minimum thickness of the rubber layer shall be in accordance with Table 3. f Naval brass is sometimes designated CuZn38Sn1 as well as CuZn39Sn. Requirements according to Table 1: 1) Steps shall be taken to ensure that no flying rust particles or flakes can be deposited on surfaces that may come into contact with each other. 2) a)
Paint containing aluminium shall not be used because of the risk of thermite sparks (EN 1127-1). SIST EN 14986:2007
EN 14986:2007 (E) 12 b)
Paint containing iron oxides shall not be used because of the risk of thermite sparks (EN 1127-1). 3) Nickel based alloys shall contain a minimum mass fraction 60 % nickel. Nickel based alloys and nickel based steel alloys shall contain a maximum mass fraction of 4 % in total of magnesium, titanium and zirconium. All alloys shall have a homogeneous structure. NOTE Even if these alloys are non sparking, they can easily form hot spots due to friction and low heat conductivity. 4) Stainless steel shall be of an austenitic grade and non-magnetic. Great care shall be taken in fabrication, machining etc. to ensure that magnetism is not induced. 5) These pairings can cause ignition of explosive atmospheres when rubbing occurs. This shall be included in the technical documentation provided to the user. They shall only be used when the clearances between rotating and stationary parts can be ensured after commissioning and during use. The manufacturer's instructions shall include the maintenance measures to ensure that the required clearance is maintained, see 7.2. These pairings shall be limited to fans having a motor power not exceeding 5,5 kW and a relative rubbing speed between stationary and rotating parts not exceeding 40 m/s, provided the clearances at all possible points of contact specified in 4.15 is ensured. Where greater motor powers or relative rubbing speeds occurs additional measures are required to control the clearance (e.g. vibration control, see 4.10). In this material pairing austenitic steel shall have a mass fraction of at least 16,5 % chrome (see [32], [39]), to minimize the probability of mechanically generated sparks in case of friction. NOTE Even if this alloy generates no sparks it can in case of friction easily generate hot surfaces because of the low thermal conductivity. 6) Plastic components shall fulfil the requirements of EN 13463-1. The manufacturer shall give details of the material specification, thermal endurance and electrostatic properties in the t
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SLOVENSKI OSIST prEN 14986:2004
PREDSTANDARD
september 2004
Načrtovanje ventilatorjev za delovanje v potencialno eksplozivnih atmosferah
Design of fans working in potentially explosive atmospheres
ICS 13.230; 23.120 Referenčna šte
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