Chemical Plant Lighting Information
In a chemical plant, proper lighting is essential for both safety and productivity. Many chemical plants operate in environments that can be explosive due to the presence of flammable gasses, vapors, or dust. In these areas, it's critical to use explosion-proof lighting fixtures that are designed to contain any sparks or explosions that might occur within the fixture, thereby preventing a larger explosion.
Lighting Classes and Divisions
The National Electric Code (NEC)/National Fire Protection Association 70 (NFPA) Article 500 lists three Hazardous (Classified) Locations which indicates the nature and degree of a hazard existing in a particular location. Article 500 provides a general description for Class 1. Article 501 provides specifics.
- A Class 1 Locations “are those in which flammable gasses, 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”.
- A Class 2 Locations "are those in which combustible dusts (either in suspension, intermittently, or periodically) are or may be present in quantities sufficient to produce explosive or ignitable mixtures."
The two Division designations defines the chance a hazardous material is present in an ignitable concentration. Article 500 provides a general description for Division 1 and 2.
- A Division 1 location is one in which:
- “Ignitable concentrations of flammable gases, flammable liquid-produced vapors, or combustible liquid-produced vapors can exit under normal operating conditions”.
- “Ignitable concentrations of such flammable gases, flammable liquid-produced vapors or, combustible liquids above their flash points may exist frequently because of repair or maintenance operations or because of leakage,” or
- “Breakdown or faulty operation of equipment or processes might release ignitable concentrations of flammable gases, flammable liquid-produced vapor, or combustible liquid-produced vapors and might also cause simultaneous failure of electrical equipment in such a way as to directly cause the electrical equipment to become a source of ignition”.
- Division 2 location is one in which:
- “Volatile flammable gases, flammable liquid-produced vapors, or combustible liquid-produced vapors are handled, processed, or used, but in which the liquids, vapors, or gases will normally be confined within closed containers or closed systems from which they can escape only in case of accidental rupture or breakdown of such containers or system or in case of abnormal operation of equipment” or
- “Where combustible dust accumulations are present but are normally insufficient to interfere with the normal operation of electrical equipment or other apparatus, but could as a result of infrequent malfunctioning of handling or processing equipment become suspended in the air,” or
- “Combustible dust accumulations on, in, or in the vicinity of the electrical equipment could be sufficient to interfere with the safe dissipation of heat from electrical equipment or could be ignitable by abnormal operation of failure of electrical equipment”.