Industrial Security - Fire Alarms and Hazardous Area Industrial Security
Since 2001
Hazardous Area, Audiovisual Signaling, Fire Alarms



HAZARDOUS AREA GUIDE

Hazardous areas are places containing flammable gases, vapors or dusts. Such places can't include ordinary electrical equipment, as high surface temperature, electric arcs or sparks could generate an explosion.
In order to prevent disasters, each type of hazardous location require special devices with the features that attend its particularities, therefore is very important to know the characteristics of the place and also what are the electrical equipment suitable for use in it.
There are two standards by which a hazardous area can be classified: European, by IEC (International Electrotechnical Commission) and American, by NEC (National Electrical Code). As the both are usual, it's relevant to observe the both, which are presented in the following tables:



Hazardous Areas Classification:


TABLE 1: HAZARDOUS AREAS CLASSIFICATION ACCORDING TO THE SUBSTANCE TYPE AND THE RISK LEVEL.
Presence of Hazardous Subtances European (IEC) Classification North American (NEC) Classification
Gases Continuously Zone 0 Class I, Division 1
Gases Sometimes (during a periodic process, for example) Zone 1 Class I, Division 2
Gases Rarely (during a casual process, for example) Zone 2 Class I, Division 2
Dusts Continuously Zone 20 Class II, Division 1
Dusts Sometimes (during a periodic process, for example) Zone 21 Class II, Division 2
Dusts Rarely (during a casual process, for example) Zone 22 Class II, Division 2
Fibers or Flammable Wastes Sometimes (during a periodic process, for example) - Class III, Division 1
Fibers or Flammable Wastes Rarely (during a casual process, for example) - Class III, Division 2



TABLE 2: HAZARDOUS AREAS CLASSIFICATION ACCORDING TO THE HAZARDOUS SUBSTANCE.
Gas / Material European (IEC) Gas Group North American (NEC) Gas Group
Methane I -
Acetylene IIC A
Hydrogen IIC B
Ethylene IIB C
Propane IIA D
Metal Dust - E
Coal Dust - F
Grain Dust - G



Electrical Equipment Classification:


TABLE 3: ELECTRICAL EQUIPMENT CLASSIFICATION ACCORDING TO THE MAXIMUM SURFACE TEMPERATURE.
Maximum Surface Temperature IEC Temperature Classification NEC Temperature Classification
450 C T1 T1
300 C T2 T2
280 C T2 T2A
260 C T2 T2B
230 C T2 T2C
200 C T3 T3
180 C T3 T3A
165 C T3 T3B
160 C T3 T3C
135 C T4 T4
120 C T4 T4A
100 C T5 T5
85 C T6 T6



TABLE 4: ELECTRICAL EQUIPMENT CLASSIFICATION ACCORDING TO THE PROTECTION TYPE.
Protection Type Ex Code Application
Flameproof d Zones 1 and 2
Increased Safety e Zones 1 and 2
Oil Filled o Zones 1 and 2
Sand / Powder / Quartz Filled q Zones 1 and 2
Encapsulated m Zone 0 (Ex ma)
Zone 1 (Ex mb)
Pressurized / Purged p Zones 1 and 2
Intrinsically Safe i Zone 0 (Ex ia)
Zone 1 (Ex ib)
Zone 2 (Ex ic)
Non Incendive n Zone 2
Special Protection s Zones 0, 1 and 2


These 4 tables above show the information that all electrical equipment for use in hazardous area should contain: where it can be used, inserted in which hazardous substance, what's the maximum surface temperature and which type of protection it has. If you need any further assistance, send your questions to info@indsecurity.com

Download the PDF version: Industrial Security PDF Logo Hazardous Area Guide (132 KB)




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