EN 14986:2007

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
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

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
(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

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

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

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 technical documentation. Plastic materials for category 2 and category 1 fans shall withstand short-term exposure to flames without burning, when tested according to 4.23. 7) If the impeller is rubber coated the tip speed shall be limited to 70 m/s. 8) This combination shall only be used when the Brass CuZn37 is employed as the stationary part. 9) In fans plastic or rubber can be used to produce linings, rings or contact strips, or as extension to metallic parts (e.g. a tip extension to a metallic blade), or to manufacture entirely the impeller, the casing or both. In all cases the minimum clearances specified in 4.15 shall be ensured between rotating and stationary parts. SIST EN 14986:2007

4.9 Linings and tip extensions If linings or tip extensions are used, then the material combination shall correspond to one of the pairings specified in 4.8.2. Where linings or tip extensions are used for ignition protection they shall have a minimum thickness or length to withstand impact or abrasion for an appreciable time. For linings the minimum thickness is given in Table 3. Table 3 — Minimum thickness of linings Thickness for category 2 mm Thickness for category 3 mm Motor power, P kW Metallic linings Non-metallic linings Metallic linings Non-metallic liningsP ≤ 11 2 3 1 2 11 < P ≤ 90 3 5 2 4 90 < P ≤ 250 4 6 3 5 250 < P 5 8 4 7
Tip extensions shall have a length of at least 3 % of the relevant contact diameter, but shall not be smaller than 5 mm in axial or radial direction and need not to be greater than 40 mm. SIST EN 14986:2007

The formation of dangerous layers within fan casings and on the surface of motors shall therefore be prevented by appropriate design. Casings shall allow for easy inspection and cleaning as appropriate (see also EN 1127-1). The impeller and housing shall be of a design that will minimise dust from attaching or settling under normal conditions. In this sense the selection of an appropriate shape of blade is particularly important. Suitable facilities (e.g. easily accessible inspection doors) shall be provided so that inspection and cleaning operations can be easily carried out. Category 2 and category 1 fans: Where the dust is liable to form thick layers, appropriate measures (e.g. vibration monitoring, maintenance intervals) shall be required to avoid hazards from potential deposits. 4.15 Clearance between rotating elements and the fan casing The clearance between rotating elements and the fan casing is the most important safety feature of ignition minimising fans. The minimum clearances between rotating parts such as the impeller and fixed parts e.g. the fan casing shall be at least 1 % of the relevant contact diameters (diameter of a rotating part at the point where it can contact a stationary part) of the finished component, but shall not be less than 2 mm in the axial or radial directions nor need be more than 20 mm. This clearance may be reduced to 10 % of the shaft diameter with a minimum of 2 mm and maximum of 13 mm. Shaft seals are not subject to these provisions. The manufacturer's instructions shall include where necessary the appropriate maintenance instructions to maintain the clearance. NOTE 1 Minimum clearance is defined as taking into account all possible tolerances due to manufacture and fitting. NOTE 2 Motor end float can be limited e.g. by the use of wave washers. NOTE 3 The clearance may change with rotation, temperature, and due to vibrations and belt drive tension. 4.16 Shaft seals Shaft seals shall comply with the requirements of EN 13463-5. Unless other measures are taken (e.g. purging with nitrogen) the material pairings used for shafts and seal casing shall comply with 4.8 and the clearances between the shaft and seal casing shall comply with 4.15. 4.17 Bearings Bearings shall comply with the requirements of EN 13463-5. 4.18 Power transmission systems Power transmission systems shall comply with the requirements of EN 13463-5 4.19 Clutches and couplings Clutches and couplings shall comply with the requirements of EN 13463-5. 4.20 Brakes and braking systems Brakes and braking systems shall comply with the requirements of EN 13463-5. SIST EN 14986:2007

NOTE
For category 2 fans 4.10 applies. b) control of ignition source ‘b’ as described in EN 13463-1 and EN 13463-6. In addition the requirements described in 5.2 and 5.3 shall be applied. SIST EN 14986:2007
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