Hazardous location — An area where the possibility of explosion and fire is created by the presence of flammable gases, vapors, dust, fibers or flyings.
Class I – Gas
Class I – Class I locations are those in which flammable gases, flammable liquid-produced vapors or combustible liquid-produced vapors are or may be present in the air in quantities sufficient to produce explosive or ignitable mixtures.
Typical class I locations:
− Petroleum refineries and gasoline storage areas
− Industrial firms that use flammable liquids in dip tanks for parts cleaning or other operations
− Petrochemical companies that manufacture chemicals from gas and oil
− Dry cleaning plants where vapors from cleaning fluids can be present
− Companies that have spraying areas where they coat products with paint or plastics − Aircraft hangars and fuel serving areas
− Utility gas plants and operations involving storage and handling of liquified petroleum gas or natural gas
Class II – Dust
Class II – Class II locations are those that are hazardous because of the presence of combustible dust.
Typical class II locations:
− Grain elevators, flour and feed mills
− Plants that manufacture, use or store magnesium or aluminum powders
− Plants that have chemical or metallurgical processes: producers of plastics, medicines and fireworks, etc.
− Producers of starch or candies
− Spice-grinding plants, sugar plants and cocoa plants
− Coal preparation plants and other carbon handling or processing areas
The following table describes a simplified comparison of the different designations for the classification of gas hazardous areas: