HAZARDOUS AREA
There are two categories used to classify hazardous areas:
A) Zones
B) Groups
A) Zone Category
1) Zone 0: Hazardous gas is present continuously.
2) Zone 1: Hazardous gas is present intermittently.
3) Zone 2: Hazardous gas can be present due to leakage.
4) Zone 20: Hazardous dust is present continuously.
5) Zone 21: Hazardous dust is present intermittently.
6) Zone 22: Hazardous dust can be present due to leakage.
Group Category
1) Group I: Mine area
2) Group II: Gas
- Group II A corresponds to Zone 0
- Group II B corresponds to Zone 1
- Group II C corresponds to Zone 2
3) Group III: Dust
- Group III A corresponds to Zone 20
- Group III B corresponds to Zone 21
- Group III C corresponds to Zone 22
PROTECTION METHODS - EXPLOSION PROOF & FLAMEPROOF
Ex Ia & Ex Ib: Intrinsically safe instruments are designed in a way that the energy produced by any spark is lower than the ignition energy of a flammable mixture. Ex Ia instruments have a higher integrity level and can be used in Zone 0 hazardous areas, while Ex Ib instruments are suitable for Zone 1 and 2 locations.
Ex d: Flameproof cable instruments are designed to contain or control an ignited flammable mixture and prevent it from igniting any external flammable mixture. This protection method is applicable in Zones 1 and 2 hazardous areas.
Ex e: Increased safety cable instruments are designed using components that do not create arcs or sparks, ensuring ignition prevention. The enclosures of these instruments can be made from thinner materials, but they must be sealed to at least IP54 ingress protection level. This protection method can be used in hazardous area Zones 1 and 2.
Ex p: Pressurized equipment that is continuously pressurized to expel flammable mixtures. This protection method can be used in Zones 1 and 2.
Ex nA: Similar to Ex e, equipment under this protection method should not create arcs or sparks, but with less stringent requirements. This protection method is limited to Zone 2 only.
Ex nR: Restricted breathing equipment is equipped with tightly fitting seals that prevent explosive mixtures from entering and reaching hot components. This protection method is limited to Zone 2 only.
INTERNATIONAL CLASSIFICATIONS OF HAZARDOUS AREAS
ATEX: The European Directive requires and certifies instruments intended for explosive atmospheres in hazardous areas to be designed and manufactured in a way that minimizes the occurrence and limits the severity of accidental explosions.
IECEx: The International Electrotechnical Commission System provides hazardous area certification for instruments to be used in potentially explosive atmospheres.
EAC EX: The TR CU Certificate of Conformity for the Russian Customs Union is mandatory for electrical equipment intended for operation or installation in hazardous areas and potentially explosive atmospheres in these countries.
INMETRO: This certification body in Brazil ensures that electrical instruments meet the requirements for use in hazardous and potentially explosive atmospheres.
CSA: An expert source for Ex testing and Ex certification of explosion-proof instruments used in hazardous locations and potentially explosive atmospheres across North America.