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statikVentilation Basics
Hazardous Location Identification:
Selecting Proper Equipment

Confined spaces are some of the most dangerous and potentially life-threatening work environments in industry, making ventilation, respiratory and PPE equipment an integral component of a total safety program. U.S. OSHA states “electical equipment must be approved by a Nationally Recognized Testing Laboratory (NRTL) “ . . . and stated in 29 CFR 1910.303(a). In addition, NRTL’s must approve this equipment using U.S. recognized test standards, 29 CFR 1910.7.” Proper selection and training with approved hazardous location safety equipment can reduce the cause of potential accidents and even loss of life. In order to select the proper equipment, the worker must first determine whether the location is considered a “Hazardous” or “Non-Hazardous” location.

  1. What is a Hazardous Location?
    All confined spaces should be considered a “Hazardous Location” until proven otherwise. Federal OSHA refers to the National Electrical Code (NEC) as the “Bible” for reference information concerning hazardous locations. NEC defines a hazardous location as those areas “where fire or explosion hazards may exist due to flammable gases or vapors, flammable liquids, combustible dust, or ignitable fibers or flyings.”
  2. NEC classifies hazardous locations in three ways: Type, Condition, and Nature:
    Three “Types” of hazardous conditions exist called Classes, describing the type of hazard expected:
    CLASS I (NEC-500-5) - Areas in which flammable gasses or vapors may be present in the air in sufficient quantities to be explosive or ignitable.
    CLASS II (NEC-500-6) - Areas made hazardous by the presence of combustible dust
    CLASS III (NEC-500-7) - Areas in which easily ignitable fibers or flyings present, due to the type of material being handled, stored, or processed
    Two kinds of hazardous “Conditions” exist called Divisions:
    DIVISION I (NEC-800-5, 6, 7) - The hazard is present continuously
    DIVISION II (NEC-500-5, 6, 7) - The hazard is atypical - may occur
    The “Nature” of the hazardous substance is called a Group (NEC-500-3).
    Groups A, B, C, or D where Group A is most volatile (Acetylene) and Group D would be least flammable (Propane). All Class I locations, Flammable Gases and Vapors, fall into Groups A, B, C or D.
    Groups E, F, and G where Group E is conductive and explosive metal dust, Group F is carbon (coal) dust, and Group G is flour and grain dust. All Class II locations, Combustible Dusts, fall under Groups E, F or G.
    Not Grouped - Hazards consisting of textile and wood fibers. Class III locations, Ignitable Fibers for Flying, are not grouped.