Hazardous (Classified) Locations

Transcription

1 Hazardous (Classified) Locations Presented by: John Chambers UL HazLoc operations Presented at: Safety & You in Safety Conference Flexible Packaging Association (FPA) 1

2 AREA CLASSIFICATIONS Class I Flammable, gases, vapors or liquids Class II Combustible dusts Class III Ignitable fibers and flyings 2

3 WHO CLASSIFIES AREAS? WHO ACCEPTS EQUIPMENT? ARE THEY THE SAME PERSON? Area Classification Vs. Authority Having Jurisdiction (AHJ) Approved vs. Listed vs. Identified 3

4 CLASS I, DIVISION 1 A Class I, Division 1 location is a location where ignitable concentrations of flammable gases, vapors or liquids: can exist under normal operating conditions; may exist frequently because of repair or maintenance operations or leakage; or may exist because of equipment breakdown that simultaneously causes the equipment to become a source of release 4

5 CLASS I, DIVISION 2 A Class I, Division 2 location is a location where: volatile flammable liquids or flammable gases or vapors exist, but are normally confined within closed containers; ignitable concentrations of gases, vapors or liquids are normally prevented by positive mechanical ventilation; or adjacent to a Class I, Division 1 location where ignitable concentrations might be occasionally communicated 5

6 CLASS I, ZONE 0 A Class I, Zone 0 location is a location where ignitable concentrations of flammable gases, vapors or liquids: are present continuously; or are present for long periods or time 6

7 CLASS I, ZONE 1 A Class I, Zone 1 location is a location where ignitable concentrations of flammable gases, vapors or liquids: are likely to exist under normal operating conditions; may exist frequently because of repair or maintenance operations or leakage; may exist because of equipment breakdown that simultaneously causes the equipment to become a source of ignition; or adjacent to a Class I, Zone 0 location from which ignitable concentrations could be communicated ignitable concentrations could be communicated 7

8 CLASS I, ZONE 2 A Class I, Zone 2 location is a location where: ignitable concentrations of flammable gases, vapors or liquids are not likely to occur in normal operation or, if they do occur, will exist only for a short period; volatile flammable liquids or flammable gases or vapors exist, but are normally confined within closed containers; ignitable concentrations of gases, vapors or liquids are normally prevented by positive mechanical ventilation; or adjacent to a Class I, Zone 1 location from which 8 ignitable concentrations could be communicated

9 Definition: MESG MESG (Maximum Experimental Safe Gap) - The maximum clearance between two parallel metal surfaces that has been found, under specified test conditions, to prevent an explosion in a test chamber from being propagated to a secondary chamber containing the same gas or vapor at the same concentration. 9

10 Definition: MIC Ratio MIC (Minimum Igniting Current) Ratio - The ratio of the minimum current required from an inductive spark discharge to ignite the most easily ignitable mixture of a gas or vapor, divided by the minimum current required from an inductive spark discharge to ignite methane under the same test conditions. 10

11 CLASS I, DIVISION 1 & 2 Group A Acetylene Group B GROUPS Gases or vapors having: MESG < 0.45 mm or MIC Ratio < 0.40 Examples are: hydrogen, fuel and combustible process gases containing more than 30 percent hydrogen by volume, butadiene, ethylene oxide, propylene oxide, and acrolein. 11

12 CLASS I, DIVISION 1 & 2 GROUPS (cont.) Group C Gases or vapors having: 0.45 mm < MESG < 0.75 mm or 0.40 < MIC Ratio < 0.80 Examples are: ethyl ether and ethylene. Group D Gases or vapors having: 0.75 mm < MESG 0.80 < MIC Ratio Examples are: acetone, ammonia, benzene, butane, cyclopropane, ethanol, gasoline, hexane, methanol, methane, naphtha, and propane. 12

13 CLASS I, ZONE 0, 1 AND 2 Group IIC GROUPS Atmospheres containing acetylene, hydrogen, or gases or vapors having: MESG < 0.50 mm MIC Ratio <

14 CLASS I, ZONE 0, 1 AND 2 GROUPS (cont.) Group IIB Atmospheres containing ethylene or acetaldehyde, or gases or vapors having: 0.50 mm < MESG < 0.90 mm 0.45 < MIC Ratio < 0.80 Group IIA Atmospheres containing acetone, ammonia, ethyl, alcohol, gasoline, methane, propane, or gases or vapors having: 0.90 mm < MESG 0.80 < MIC Ratio 14

15 CLASS II, DIVISION 1 A Class II, Division 1 location is a location where: Ignitable concentrations of combustible dust can exist in the air under normal operating conditions; Ignitable concentrations of combustible dust may exist because of equipment breakdown that simultaneously causes the equipment to become a source of ignition; or Electrically conductive combustible dusts may be present in hazardous quantities 15

16 CLASS II, DIVISION 2 A Class II, Division 2 location is a location where: combustible dust is not normally in the air in ignitable concentrations; dust accumulations are normally insufficient to interfere with normal operation of electrical equipment; Dust may be in suspension in the air as the result of infrequent malfunction of equipment; or Dust accumulation may be sufficient to interfere with safe dissipation of heat or may be ignitable by abnormal operation 16

17 CLASS II, DIVISION 1 ONLY GROUP Group E Atmospheres containing combustible metal dusts including aluminum, magnesium and their commercial alloys, or other combustible dusts whose particle size, abrasiveness, and conductivity present similar hazards in the use of electrical equipment 17

18 CLASS II, DIVISION 1 AND 2 GROUPS Group F Atmospheres containing combustible carbonaceous dusts, including carbon black, charcoal, coal or dusts that have been sensitized by other materials so that they present an explosion hazard Group G Atmospheres containing combustible dusts not included in Group E or F, including flour, grain, wood, plastic, and chemicals 18

19 CLASS I, DIVISION 1 AND 2 and CLASS II TEMPERATURE CLASSES T1 (<450º C) T2 (< 300º C) T2A, B, C, D (< 280º C, < 260ºC, < 230ºC, < 215º C) T3 (< 200º C) T3A, B, C, (< 180º C, < 165º C, < 160º C) T4 (< 135º C) T4A (< 120º C) T5 (< 100º C) T6 (< 85º C) 19

20 CLASS I, ZONE 0, 1 AND 2 TEMPERATURE CLASSES T1 (< 450 C) T2 (< 300 C) T3 (< 200 C) T4 (< 135 C) T5 (< 100 C) T6 (< 85 C) 20

21 CLASS III, DIVISION 1 A location in which easily ignitable fibers or materials producing combustible flyings are handled, manufactured or used 21

22 CLASS III, DIVISION 2 A location in which easily ignitable fibers are stored or handled 22

23 CLASS III, DIVISION 1 AND 2 GROUPS Not divided into groups 23

24 CLASS III, DIVISION 1 AND 2 TEMPERATURE LIMITS Article 503 of the NEC limits maximum temperatures for Class III equipment 165 C for equipment not subject to overloading 120 C for equipment that may be overloaded 24

25 CLASS I DIVISION /ZONE AREA CLASSIFICATION COMPARISON Division 1: Where ignitable concentrations of flammable gases, vapors or liquids can exist all of the time or some of the time under normal operating conditions Zone 0: Where ignitable concentrations of flammable gases, vapors or liquids can exist all of the time or for long periods of time under normal operating conditions Division 2: Where ignitable concentrations of flammable gases, vapors or liquids are not likely to exist under normal operating conditions Zone 1: Where ignitable concentrations of flammable gases, vapors or liquids can exist some of the time under normal operating conditions Zone 2: Where ignitable concentrations of flammable gases, vapors or liquids are not likely to exist under normal operating conditions 25

26 Division 1 and 2 Zone 0, 1 and 2 A (acetylene) B (hydrogen) C (ethylene) D (propane) IIC (acetylene & hydrogen) IIB (ethylene) IIA (propane) 26

27 CLASS I DIVISION/ZONE TEMPERATURE CLASS COMPARISON Division 1 and 2 Zone 0, 1 and 2 T1 (<450º C) T1 (<450º C) T2 (<300º C) T2 (<300º C) T2A,B,C,D (<280º C, <260º C, <230º C, <215º C) T3 (<200º C) T3 (<200º C) T3A,B,C, (<180º C, <65º C, <160º C) T4 (<135º C) T4 (<135º C) T4A (<120º C) T5 (<100º C) T5 (<100º C) T6 (<85º C) T6 (<85º C) 27

28 COMPARISON OF PRODUCT MARKINGS U.S. CANADA EUROPE IEC Class I, Div. 1, Group C,D Class I, Div. 1, Group C,D EEx de IIB T5 Certificate No. Ex de IIB T5 Cert. Number Class I, Zone 1 AEx de IIB T5 Ex de IIB T5 Additional for ATEX: 0539 II 2 G

29 CLASS I, DIVISION 1 AND 2 PROTECTION TECHNIQUES Area Division 1 Division 2 Protection Techniques Explosionproof Intrinsically Safe (2 fault) Purged/Pressurized (Type X or Y) Hermetically Sealed Nonincendive Circuits Nonincendive Components Nonincendive Equipment Non-Sparking Oil Immersion Purged/Pressurized (Type Z) Sealed Devices Any Class I, Division 1 technique Any Cl. I, Zn. 0, 1, or 2 technique 29

30 CLASS II, DIVISION 1 AND 2 PROTECTION TECHNIQUES Area Division 1 Protection Techniques Dust-Ignitionproof Intrinsically Safe Pressurized (Type X or Y) Division 2 Dusttight Nonincendive Circuits Nonincendive Components Nonincendive Equipment Pressurized (Type Z) Any Class II, Division 1 technique 30

31 CLASS III, DIVISION 1 AND 2 PROTECTION TECHNIQUES Area Protection Techniques Division 1 & 2 Dusttight Intrinsically Safe 31

32 CLASS I, ZONE 0 AND 1 PROTECTION TECHNIQUES Area Zone 0 Zone 1 Protection Techniques Intrinsically Safe (2 fault), ia Class I, Division 1 Intrinsically Safe (2 fault) Encapsulated, m Flameproof, d Increased Safety, e Intrinsically Safe (1 fault), ib Oil Immersed, o Powder Filled, q Purged/Pressurized, p Any Class I, Zone 0 technique Any Class I, Division 1 technique 32

33 CLASS I, ZONE 2 PROTECTION TECHNIQUES Area Protection Techniques Zone 2 Energy Limited nc ( nl in EN50021) Hermetically Sealed, nc Nonincendive, nc Non-Sparking, na Pressurization nz ( np in EN50021) Restricted Breathing, nr Sealed Device, nc Any Class I, Zone 0 or 1 technique Any Class I, Division 1 or 2 technique 33

34 ORDINARY LOCATIONS REQUIREMENTS For all equipment: Risk of Fire Risk of Electric Shock Special Applications: Environmental Ratings Marine Ratings Signaling/Fire Alarm 34

35 OTHER HAZARDOUS LOCATIONS REQUIREMENTS Some examples of requirements that may apply to multiple protection techniques include: Marking/Labeling Static Electricity Thermal Shock on glass parts Vibration Test 35

36 EXPLOSIONPROOF EQUIPMENT Equipment that has an enclosure capable of: withstanding an explosion of a specified gas or vapor that is expected to occur within the enclosure, preventing the ignition of a specified gas or vapor surrounding the enclosure due to sparks, flashes or explosion of the gas or vapor within the enclosure, and operating at an external temperature that will not ignite a specified gas or vapor surrounding the enclosure 36

37 Enclosure with enlarged gap, ready for an explosion test

38 4 5 Each frame = 1/2000 seconds 6 38

39 WITHSTANDING THE PRESSURE OF AN EXPLOSION The ability of an enclosure to withstand an explosion without rupture or permanent distortion is dependent upon: the strength of the enclosure material, and securement means, such as bolts 39

40 WITHSTANDING THE PRESSURE OF AN EXPLOSION (CON T) The strength of the enclosure material and securement means is determined by the following requirements: type of metal or metal alloy (zinc & magnesium are not allowed) type of plastic (including resistance to chemical atmospheres) casting/molding design minimum thickness hydrostatic pressure testing 40

41 PREVENTING THE IGNITION OF SURROUNDING ATMOSPHERE DUE TO PROPAGATION The ability of an enclosure to prevent ignition of a specified gas or vapor surrounding the enclosure is dependent upon the ability of any path from the interior to the exterior of the enclosure (or flame paths) to: prevent the escape of any flames, sparks or hot particles capable of ignition, and sufficiently cool the vented material 41

42 PREVENTING THE IGNITION OF SURROUNDING ATMOSPHERE DUE TO PROPAGATION (CON T) The suitability of these flame paths to prevent ignition is determined by the following requirements: Joint widths and clearances Shaft lengths and clearances Thread engagement Explosion testing 42

43 EXPLOSIONPROOF JOINT REQUIREMENTS More Restrictive than Flameproof May be: Flat Threaded Rabbet (Spigot) Labyrinth Cylindrical 43

44 JOINT COMPARISON EXAMPLE Group C (IIB) Enclosure Volume 2000 cm³ (122 in³) Explosionproof Flameproof Width 19.1 mm (3/4 in) 12.5 mm Clearance 0.05 mm (0.002 in) 0.2 mm 44

45 EXPLOSION TESTS: Minimum 10 Tests Covers the Explosive Range Covers both Reference Pressure and Non-transmission 45

46 TEST GAS MIXTURES Group A Acetylene 5-20% Group B Hydrogen 15-35% Group C Ethylene 4-9 % Group D Propane 3-7 % 46

47 Explosion Testing The custom built, Process Control and Gas Monitoring Panel enables the technician to fully control tests from outside the test room. Remote video cameras connected to monitors on top of the control panel, allow the technician to view the device under test. The entire test area is also monitored (video & audio) to ensure that nobody is in the room before conducting a test. With these features in place, personnel safety is maximized. The test area has been accident free in its four decades of operation. 47

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49 The device under test is placed inside a wood chamber and is set-up with inlet & outlet connections to introduce explosive gas-air mixtures through the device and the wood chamber. Pneumatically actuated valves are used to isolate the explosive gas-air mixture in the device from the explosive gas-air mixture in the wood chamber. 49

50 A thin sheet of clear plastic is installed over the wood chamber and provides a seal to maintain an explosive atmosphere within the chamber, and also enables the device to be viewed during the testing process. If the explosive atmosphere within the wood chamber ignites, the pressure from the explosion will vent out through the clear plastic cover which will prevent the explosion from destroying the wood chamber. A spark plug is used to ignite the explosive mixture within the device. The spark plug is placed at a location in the device where an arc may occur from electrical components or wiring that would normally be present in the device. 50

51 Quartz Piezoelectric pressure transducers are installed into the device under test and connected to an oscilloscope for the purpose of measuring the internal explosion pressure developed during the explosion test series. The maximum pressure obtained from the test series will be used to further test the strength of the device after the explosion test series. 51

52 HYDROSTATIC PRESSURE TEST The device must withstand a hydrostatic test based on the maximum explosion pressure No rupture or permanent distortion For example: maximum explosion pressure of 100 PSI = 400 PSI hydrostatic test for 10 seconds 52

53 PREVENTING THE IGNITION OF SURROUNDING ATMOSPHERE DUE TO TEMPERATURE The ability of an enclosure to prevent ignition of a specified gas or vapor surrounding the enclosure is also dependent upon how heat- producing components within the enclosure affect the temperature on the external surface of the enclosure. 53

54 PREVENTING THE IGNITION OF SURROUNDING ATMOSPHERE BY TEMPERATURE (CON T) The affect of these internal heat-producing components is determined by the following requirements: temperature testing (determines Temperature Class) marking of Temperature Class (T-Code) restriction that T-Code must be less than the autoignition temperature of surrounding atmosphere 54

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60 Explosionproof Pushbutton Switch Cylindrical Joint ---> <---Threaded Joint Flat Joint---> Threaded Conduit Entries 60

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