Hazardous Area Classification (HAC) study is done to evaluate and assess the Plant area based on the presence of Flammable material within the facility. HAC study provides details of Hazardous and Non-hazardous areas in a facility. It explains the possibilities of occurrence of hazardous events such as Fire and Explosion within the facility. Two systems are employed to carry out the study, namely Class or Division system and Zone system.
Areas that constitute Installations of Gas Wells and Gas Processing Plants, oil rigs, process refinery, chemical producing facility, flammable liquid storage facility, fuel transportation facility, Fuel station, Paint Manufacturing Facility, Paper producing Facility are examples of Hazardous Area.
An area in which the atmosphere holds sufficient quantity of flammable gases, dusts or vapors, and provides a possibility for fire or explosion to occur is considered as a Hazardous Location.
An Area in which an explosive atmosphere is present in enough quantities and requires precaution measures for fabrication, fitting and use of equipment is called Hazardous Area.
An Area in which an explosive atmosphere is not present and does not require precaution measures for fabrication, fitting and use of equipment is called Non-Hazardous Area.
Hazardous area classification has four major steps. They are,
Hazardous Area Classification Study report helps to identify potentially hazardous and explosive area, determination of extent of hazardous zone and recommends locations for installing special equipment within different zones. As HAC Risk Assessment the report provides design requirements and guidelines for selecting and identifying location of hazardous equipment's in oil & gas / petrochemical / other industries.
The following are the five main objective of HAC in a Process plant,
In most of the Installations the risk depends on the duration of hazards such as Gas, Vapor, Dust or Fiber present in the surrounding. In order to catalogue these dangers an Installation is segregated into risk areas based upon the duration of hazards present. These risk areas are referred as Hazardous Area Zones.
|GAS/VAPOUR||DUST||HAZARDOUS ZONE ATTRIBUTES|
|ZONE 0||ZONE 20||A hazardous condition is likely to be present and may exist for long periods of time or even continuously.|
|ZONE 0||ZONE 21||A hazardous condition is possible but unlikely to exist for long periods of time.|
|ZONE 0||ZONE 22||A hazardous condition is not likely to exist during normal operation for short span of time.|