Definition of Hazardous Area Classification (HAC)
Hazardous Area Classification (HAC) is a systematic method used to identify and categorize areas where flammable gases, vapors, mists, or dust may be present in sufficient quantities to create a risk of fire or explosion.
Under International Electrotechnical Commission (IEC) standards particularly IEC 60079 series HAC helps determine:
. The likelihood of hazardous substances being present
. The duration of their presence
IEC Zone Classification System
IEC standards classify hazardous areas into zones based on how frequently explosive atmospheres occur.
For gases/vapors:
Zone 0: Explosive atmosphere present continuously or long-term
Zone 1: Likely during normal operation
Zone 2: Unlikely, short duration
For Dust:
Zone 20, 21, 22 (same concept applied to combustible dust)
Basis of HAC According to IEC 60079
Basis of HAC (IEC 60079):
. Source of Release: Where flammable substances may leak (valves, tanks)
. Grade of Release: Continuous, primary, or secondary
. Ventilation: How quickly hazards disperse
. Substance Properties: Flash point, ignition temperature, density
. Operating Conditions: Pressure, temperature, process behavior
Why HAC Is Critical
. Explosion Prevention: Ensures correct equipment and safe installation
. Equipment Selection: Determines required explosion-protected (Ex) equipment
. Legal Compliance: Meets IEC-based regulations and insurance requirements
. Risk Management: Identifies high-risk areas and guides mitigation, improving safety culture
. Cost Efficiency: Prevents overuse of expensive explosion-proof equipment
Conclusion
HAC is a key safety practice under IEC standards. It identifies where and how often explosive atmospheres may occur, guiding equipment selection, operational safety, and regulatory compliance.