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Hazardous Area Classification

This document discusses hazardous area classification which assists in selecting electrical equipment to prevent ignition risks. It classifies hazardous areas into Zones 0, 1 and 2 based on the likelihood of an explosive atmosphere occurring, and provides examples of areas that fall under each zone. The document emphasizes using area classification knowledge at workplaces by implementing layout features and control measures as per the classification.

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298 views1 page

Hazardous Area Classification

This document discusses hazardous area classification which assists in selecting electrical equipment to prevent ignition risks. It classifies hazardous areas into Zones 0, 1 and 2 based on the likelihood of an explosive atmosphere occurring, and provides examples of areas that fall under each zone. The document emphasizes using area classification knowledge at workplaces by implementing layout features and control measures as per the classification.

Uploaded by

raj
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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TECHNICAL BULLETIN

Classification of Hazardous Area


Why Hazardous Areas Classification required?
In industry the presence of flammable gas or vapour, in air under normal conditions poses risk.
Source of ignition in such atmosphere may cause fire & explosion.
Hazardous area classification assists selection of electrical equipment for preventing ignition risk.
Area classification methods provide information on likelihood of explosive mixture.
Hazardous area classification
Hazardous Area is classified in ZONEs as per International Electrotechnical Commission (IEC) IEC 60079
which is the international standard for area classification. OISD 113 and IS 5571/72 are based on the
above IEC standards.
Zone 0 - An area in which an explosive atmosphere is present continuously or for long periods or
frequently. Examples are vapour space above closed process vessels, storage tanks or closed containers,
areas containing open tanks of volatile, flammable liquids etc.
Zone 1 - An area in which an explosive atmosphere is likely to occur in normal operation occasionally.
Examples are peripheral seals of floating roof tanks, Pump rooms, Sample Retention Room/ Cabinet,
API Separators, Oily waste water sewer/ basins/ Oil catchers, vicinity of vents and filling hatches
Zone 2 - An area in which an explosive atmosphere is not likely to occur in normal operation but, if it
does occur, will persist for a short period only. Locations adjacent to Zone-1 areas

Example: Area Classification for pressure storage tank or Bullet (Heavier than Air Gases or Vapour) .

Use Area classification knowledge at workplace?


Layout and provision features as per area classification.
Control of activities by engineering or administrative measures to prevent fire & explosion.
Selection of electrical equipment fittings should be suitable for the area classification.
All gas/ Class A / B and High temperature Class C plant areas comes under Zone-1, hot work in
such areas require to follow specific procedures.
Reference:
OISD-STANDARD-113 classification of areas for electrical installations at hydrocarbon processing and handling
facilities
IEC 60079 : Electrical Apparatus for explosive gas atmospheres Part 10: Classification of hazardous area
IS 5572 : Classification of Hazardous Areas (other than mines) having Flammable Gases &
Vapours for Electrical Installations.
This document for awareness and HPCL internal circulation only. Corporate HSE, T B -9/15 (R)
For decision making, the reference standard to be referred.

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