Selection of Explosion Protected Equipment for Hazardous Locations. Compiled by: Pieter Coetzee ZONE 2 ZONE 1 ZONE 0.

Transcription

1 Selection of Explosion Protected Equipment for Hazardous Locations Compiled by: Pieter Coetzee ZONE 2 ZONE 0 ZONE 1 Be safe be Ex

2 Contents Introduction Occupational Health and Safety Act. (Act 85 of 1993) & ARP 0108 Area Classification Equipment Protection Levels (EPL) Temperature Classification Different Ex Techniques Marking of Ex Equipment Selection of EPE Conclusion

3 Introduction Hazardous Location Definition An area in which an explosive gas atmosphere or combustible dust, in the form of a cloud is present, or may be expected to be present, in quantities such as to require special precautions for the construction, installation and use of equipment Explosion protected descriptive of electrical apparatus designed and approved for use in hazardous locations in accordance with a suitable protection method, including Ex d, Ex i, Ex e, Ex p, Ex na, Ex s, Ex m and Ex q

4 Three components are required for an explosion or fire to occur Oxygen Flammable Substance Ignition Source

5 Possible results from explosions, incidents and fires Includes Loss of life Loss of production (Financial Impact) Damage to plants Environmental impact

6 Occupational Health and Safety Act. (Act 85 of 1993) Act The Act shall refer to the latest issue of the Occupational Health and Safety Act 85/1993 (OHSA). To meet safety requirements as per section 44 of the OHS Act. (EMR 9(1)) Every employer or user shall identify all hazardous locations and classify them in accordance with the relevant health and safety standard incorporated into these Regulations under section 44 of the act.

7 Occupational Health and Safety Act. (Act 85 of 1993) To ensure legal compliances at all time EMR 9(3) requires that: every employer or user referred to in sub regulation (1) shall be in possession of a certificate in a form acceptable to the chief inspector which has been issued by an approved inspection authority and in which it is certified that the electrical machinery referred to in sub regulation (2) has been manufactured and tested for the groups of dangerous articles in accordance with the relevant health and safety standard incorporated into these Regulations under section 44 of the Act: Provided that in lieu of such certificate an inspector may approve permanent labelling on such machinery, which label shall contain all the relevant information.

8 ARP 0108 Annex c Upgrading and maintenance of EPE certificates for mines and factories C.1 In South Africa, all EPE used in underground mines (Group I) and on surface (Group II) shall be covered by an IA certificate. The requirements in C.2 to C.15 cover the validity of IA certificates. C.2 All IA certificates issued shall have a validity period of 10 years. Where a product is in service and its certificate has expired it will not be affected. IA certificates based on overseas certification will be valid for a period of one year

9 Responsibilities and Authorities Description Regulation Standard Responsibility Area Classification EMR 9(1) EIR 4(1) Selection of Ex equipment EMR 9(1) EIR 4(1) Installation of Ex equipment EMR 9(1) EMR 9(2) SANS SANS SANS SANS EIR 4(1) Certification of Ex equipment EMR 9(1) SANS Maintenance and inspection of Ex equipment EMR 9(8) EIR 2(1) ARP 0108 SANS SANS Plant owner (Competent personnel; committees or consultant) Production Manager Plant owner and projects ( Engineering) Electrical Engineering Manager Plant owner done by own personnel or contractors SGI-MOR Approved test Laboratory(ATL) Plant owner( All Ex equipment must be inspected every two years) OSH ACT Repair of Ex equipment EIR 2(1) SANS SANS Approved test Laboratory(ATL) SABS; EXPLOLABS; MASC Certificate of compliance(coc) - SANS MIE test installation and make sure it complies and then issue a COC Mechanical Equipment EN & 3 Mechanical

10 Area Classification /Map

11 Important information on Area Classification drawing/map

12 Important information on Area Classification drawing /Map

13 Three zones for gases and vapours Substance Zones Frequency of formation of explosive atmosphere Gases and Vapours 0 Location in which an explosive gas/vapours or mist atmosphere is present continuously or for long periods. 1000hrs + per year 1 Location in which an explosive gas/vapours or mist atmosphere is likely to occur in normal operation hrs per year 2 Location in which Gas/Vapours or mist atmospheres present during abnormal circumstances hrs per year Examples Zone 0 is not found in the open air but inside vessels or badly ventilated rooms. Zone 1 are normally small volumes found around sample points or pump seals at certain frequency a day.(eg. Twice a day) Large part of the plant is normally a Zone 2 area for eg. abnormalities at flanges or sample points. Zone 0 is the most severe zone (the highest probability of flammable atmosphere presence). Equipment for this zone requires the most stringent protection against providing a source of ignition.

14 Example of a typical zone activity would be filling a barrel of petrol in an enclosed area Zone 2 Zone 0 Zone 1 Zone 1 Zone 0 Zone 0 Zone 1 Zone 2 Present continuously or for long periods Likely to occur in normal operation Present during abnormal circumstances. 1000hrs + per year hrs per year hrs per year

15 Area divided into Zones Zone 0 Zone 1 Zone 2 Present continuously or for long periods. 1000hrs + per year Likely to occur in normal operation hrs per year Present during abnormal circumstances hrs per year Vent Bund Wall Liquid

16 Flammable substance Hazardous areas are defined by three main criteria: The type of hazard The likelihood of the hazard being present in flammable concentrations The (auto) ignition temperature of the hazardous material The type of hazard (Groups) The hazard will be in the form of a gas, vapour, dust or fibre. Gases and Vapours (Group I/II) Gases and vapours are categorized in terms of their ignition energy or the maximum experimental safe gap (in respect of flameproof protection). This categorization leads to the Gas Groups:

17 Gas Groups Industry Mining Industry Group I Surface Industry Group II Gas Group I IIA Substance MIE Selection of equipment Methane 200µJ Equipment only suitable for mines unless it is additional approved for surface: Marked I/IIC Propane 180 µj and higher IIA; IIB and IIC certified equipment may be use in an IIA area. IIB Ethylene 60 µj -180 µj IIB and IIC certified equipment may be used in an IIB area. IIC Hydrogen 20 µj 60 µj Only IIC certified equipment is allowed to be used in an IIC area. (The gases noted in the table are typical gases for each group.) MIE Minimum ignition energy Gas Group IIC is the most severe gas group

18 Temperature Classes Explosion proof equipment, installed within the Ex area, is divided into 6 temperature classes (T1 to T6). Temperature class is not as it is often wrongly believed the operating temperature range of the equipment, but the maximum permissible surface temperature of the equipment, in relation to + 40 C ambient temperature on any surface area, and should not be exceeded at any time. The maximum surface temperature must remain below the ignition temperature of the surrounding medium at all times. The equipment requirements increases from T1 to T6. T-Class Maximum surface temperature of the equipment Ignition temperatures of combustible substances T1 450 C > 450 C T2 300 C > 300 C T3 200 C > 200 C T4 135 C > 135 C T5 100 C > 100 C T6 85 C > 85 C

19 Auto-ignition temperatures (vapours/gases and dust) Vapours/gases Gas Temperature Methane 580 C Hydrogen 560 C Propane 493 C Ethylene 425 C Acetylene 305 C Naphtha 290 C Carbon disulfide 102 C Dust Substance Temperature Sugar 460 C Wood 340 C Flour 340 C Grain dust 300 C Tea 300 C

20 Equipment Protection Level (EPL) Group Ex risk Zone EPL I (mines) energized Ma I (mines) de-energized in presence of Ex atmosphere Mb Minimum type of protection II (gas) II (gas) II (gas) explosive atmosphere > 1000 hrs/yr explosive atmosphere between 10 and 1000 hrs/yr explosive atmosphere between 1 and 10 hrs/yr 0 Ga ia, ma 1 Gb ib, mb, px, py, e, o, q, s 2 Gc n, ic, pz III (dust) III (dust) III (dust) explosive surface > 1000 hrs/yr explosive surface between 10 and 1000 hrs/yr 20 Da 21 Db explosive surface between 10 and Dc

21 Different Ex Techniques Technique Protection Type Symbol Application Typical application Energy Limiting Intrinsic Safety Ex ia Zone o Instrumentation; Ex ib Zone 1 control gear Ex ic Zone 2 Ex iad Zone 20 Containment Flameproof Ex d Zone 1 & 2 Switchgear; motors; pumps Principle Refined Mechanical design Refined Mechanical design Segregation (Isolation) Increase Safety Ex e Zone 1 & 2 Motors; Light fittings Non-sparking Ex na Zone 2 Motors; Light fittings Pressurization Exp; Ex pd Zone 1& 2 Zone 21 Motors; analysers; control rooms Segregation (Isolation) Encapsulation Ex m; Ex md Zone 1& 2 Zone 20 Solenoids; fuses; relays Segregation (Isolation) Sand filling Ex q Zone 1 & 2 Strip heaters, capacitors

22 Marking of Ex equipment E Ex ia IIC T6 Ga Equipment protection level (EPL) Temperature Classification (T-Class) identifies the maximum ignitioncapable surface temperature which the equipment will exhibit.(t6 =85 C) Unless otherwise stated, the maximum ambient temperature to which the equipment may be subjected (and thus the maximum ambient temperature for which the T-Class will be true) is 40 C Gas Group/Apparatus Group The roman II indicates surface industry (not mining). IIC is the most onerous subgroup in Group II. Equipment which is suitable for IIC will also be suitable for IIA and IIB Code letters indicate the type of protection (or types) of protection utilized by this equipment. ia indicates Intrinsic Safety Ex: is the symbol for explosion protection The initial E indicating conformity with European EN standards. This E is no longer used so it will not be shown on equipment which has been designed and certified since around 2007

23 Selection of EPE for hazardous location Equipment marking Ex d IIC T5 Gb - 20 to 40 C Verification sheet Area Equipment Compliance Zone 1 d (Gb) Suitable Gas Group IIB IIC Suitable Temperature class T4 T5 Suitable Ambient temperature - 20 to 40 C - 20 to 40 C Suitable

24 Conclusion