Selection of Equipment & Type of Ex Protection for Dust locations. Aug. 2010 Mike Scott : EXB Electric (Pty) Ltd. www.exbelectric.co.za Tel. + 27 11 887 8941 Fax. + 27 11 887 8945
Thank You Peter Turnherr , CEO of thuba and a member of numerous working groups and committees (IEC) associated with Explosion Protection. Peter has made available a lot of information and material used in this presentation. The thuba group of companies are mainly concerned with various aspects of Explosion Protection. EXB Electric (Pty) Ltd.
Disclaimer All information in this presentation is given in good faith and does NOT replace standards, codes of practice and any other requirements of industry or other. EXB Electric (Pty) Ltd and / or the writer / presenter will / are NOT responsible for any errors / miss- understandings. EXB Electric (Pty) Ltd.
International Standards IEC 60079-14 IEC 60079-17 IEC 60079-19 EXB Electric (Pty) Ltd.
Qualifications of personnel The design of the installation, the selection of equipment and the erection covered by this standard shall be carried out only by persons whose training has included instruction on the various types of protection and installation practices , relevant rules and regulations and on the general principles of area classification. The competency of the person shall be relevant to the type of work to be undertaken. EXB Electric (Pty) Ltd.
Information required • Classification of the hazardous area including the equipment protection level requirements where applicable • Where applicable, dust classification in relation to the subgroup of the electrical equipment • Surface temperature of the dust involved EXB Electric (Pty) Ltd.
Information required • Minimum ignition temperature of the combustible dust cloud, minimum ignition temperature of the combustible dust layer and minimum ignition energy of the combustible dust cloud • External influences and ambient temperature EXB Electric (Pty) Ltd.
General requirements Hazardous areas are classified into Zones 20, 21 and 22 for combustible dusts according to IEC 60079-10-2 in order to facilitate the selection of appropriate electrical equipment and the design of suitable electrical installations. EXB Electric (Pty) Ltd.
General requirements Electrical installations in hazardous areas shall also comply with the appropriate requirements for installations in non-hazardous areas. SANS 10142 in RSA However the requirements for non-hazardous areas are in sufficient for installations in hazardous areas. SANS 10086 in RSA EXB Electric (Pty) Ltd.
General requirements Equipment shall be installed in accordance with its documentation. EXB Electric (Pty) Ltd.
General requirements Installations should be designed and equipment and materials installed with a view to providing ease of access for inspection and maintenance (IEC 60079-17). EXB Electric (Pty) Ltd.
Selection of repaired, second hand or existing equipment When it is intended that existing, second hand or repaired equipment is to be installed in a new installation, it shall only be reused if: a) it can be verified that the equipment is unmodified and is in a condition that meets the content of the original certificate (including any repair or overhaul) b) any changes to equipment standards relevant to the item considered do not require additional safety precautions. EXB Electric (Pty) Ltd.
Use of equipment that is not certified simple electrical apparatus used within an intrinsically safe circuit . (The I S loop needs certification) EXB Electric (Pty) Ltd.
Equipment Protection Level (EPL) Zone Equipment Protection Level (EPL) 20 Da 21 Db and Da 22 Dc, Db and Da EXB Electric (Pty) Ltd.
Comparison of Dust Zones and Gas Zones. Dust (Zone 20) ~ Gas (Zone 0) Dust (Zone 21) ~ Gas (Zone 1) Dust (Zone 22) ~ Gas (Zone 2) (NB: approximately ) EXB Electric (Pty) Ltd.
Type of protection and EPL EPL Type of protection Code Standard General requirements IEC 60079-0 Protection by enclosure ta IEC 60079-31 Da Protection by intrinsic safety iaD IEC 61241-11 Protection by encapsulation ma IEC 60079-18 EXB Electric (Pty) Ltd.
Type of protection and EPL EPL Type of protection Code Standard Protection by enclosure tb IEC 60079-31 Protection by intrinsic safety ibD IEC 61241-11 Db Protection by encapsulation mb IEC 60079-18 Type of protection „pD“ pD IEC 61241-4 EXB Electric (Pty) Ltd.
Type of protection and EPL EPL Type of protection Code Standard Protection by enclosure tc IEC 60079-31 Dc Protection by encapsulation mc IEC 60079-18 Type of protection „pD“ pD IEC 61241-4 EXB Electric (Pty) Ltd.
Suitability of apparatus for less hazardous locations. DUST Hazardous Locations EPL level Da : Suitable for Zones 20 & 21 & 22 EPL level Db : Suitable for Zones 21 & 22 EPL level Dc : Suitable for Zone 22 ONLY GAS Hazardous Locations EPL level Ga : Suitable for Zones 0 & 1 & 2 EPL level Gb : Suitable for Zones 1 & 2 EPL level Gc : Suitable for Zone 2 ONLY EXB Electric (Pty) Ltd.
Group III (Dust) Equipment groups (dust) IIIA Fibres IIIB Non-conductive dust IIIC Conductive dust EXB Electric (Pty) Ltd.
Comparison of Equipment Groups. Group I : Fiery Mines, (Firedamp (Methane / Coal Dust)) Group II : Industries other than mines. (surface industries) Group II A : Propane for Example Group II B : Ethylene for Example Group II C : Hydrogen gas for Example Group III : Dusts. Group III A : Fibres. Polyester / cotton for example Group III B : Non Conductive dust. Grain for example Group III C : Conductive dust. Aluminum for example EXB Electric (Pty) Ltd.
Dust clouds Temperature limitations because of the presence of dust clouds The maximum surface temperature of the apparatus shall not exceed two-thirds of the minimum ignition temperature in degrees Celsius ( C) of the dust/air mixture concerned: T max ≤ ⅔ T CL where T CL is the minimum ignition temperature of the cloud of dust EXB Electric (Pty) Ltd.
Dust layers • Temperature limitation because of the presence of dust layers – up to 5 mm thickness – above 5 mm up to 50 mm – dust layers above 50 mm EXB Electric (Pty) Ltd.
EXB Electric (Pty) Ltd.
Dust layers EXB Electric (Pty) Ltd.
Plugs and socket outlets for dust • Socket outlets shall be installed so that dust will not enter the socket outlet with or without a plug in place. • To minimize the ingress of dust in the event of a dust cap being accidentally left off, socket outlets shall be positioned at an angle, which is not more than 60 degrees to the vertical, and the opening facing downwards. EXB Electric (Pty) Ltd.
Plugs and socket outlets for dust ≤ 60 ° EXB Electric (Pty) Ltd.
External factors • Thermal effects • Chemical effects • Mechanical effects • Varying pressure conditions • Effects of movement and vibration • Electrical effects • Moisture • Ingress of process liquids • Corrosion • Small animals, rodents and insects EXB Electric (Pty) Ltd.
Ambient temperature Equipment shall normally be designed for use in an ambient temperature range between – 20 ºC and 40 ºC; in this case, no additional ambient temperature marking is required. Example of extended ambient temperature range T amb T amb – 30 C to 65 C. EXB Electric (Pty) Ltd.
Ambient temperature EXB Electric (Pty) Ltd.
Ambient temperature EXB Electric (Pty) Ltd.
Standards for dust EN 60079 – 0 : 2009 - 08 General Requirements EN 60079-10-2:2009 IEC 61241-2-1 EN 60079-31:2008 Area classification Methods for determining the minimum Protection by Enclosure «t» ignition temperatures of dust EN 60079-14:2009 IEC 61241-2-2 EN 61241- 4:2006 Electrical installation design, Method for determining the electrical Protection by Pressurization «pD» resistivity of dust in layers selection and erection IEC 61241-20-3 EN 61241-11:2006 EN 60079-17:2007 Method for determining minimum ignition Intrinsic Safety «iD» Inspection and maintenance energy of dust/air mixtures EN 60079-18:2008 EN 60079-19:2007 Protection by Encapsulation «m» Repair and Overhaul EXB Electric (Pty) Ltd.
Protection by Enclosure «t»
Group III Equipment groups (dust) IIIA fibres IIIB non-conductive dust IIIC conductive dust EXB Electric (Pty) Ltd.
Protection by enclosure «t» Limiting surface Thermal 1. temperature tests Aging resistance testing Hot and cold 2. storage tests (thermal endurance) Testing for mechanical 3. Impact test strength Testing for dust Ingress test in 4. protection dust test chamber Take appropriate 5. Electrostatics measures EXB Electric (Pty) Ltd. 36
Protection by enclosure «t» Sequence of tests Testing for aging resistance Testing for mechanical strength Testing for dust protection Evaluation of dust protection taking into consideration aging and mechanical influences EXB Electric (Pty) Ltd.
Protection by enclosure «t» Dust ingress protection IP 6X Equipment for Zones 20 and 21 Equipment for Zone 22 with conductive dust Dust ingress protection IP 5X Equipment for Zone 22 with non-conductive dust EXB Electric (Pty) Ltd.
Protection by enclosure «t» EXB Electric (Pty) Ltd.
Intrinsic Safety «iD»
Recommend
More recommend