SPRAY APPLICATION, DIPPING,

AND COATING PROCESSES 516-1. Scope. This article covers the regular or frequent application of flammable liquids, combustible liquids, and combustible powders by spray operations and the application of flammable liquids, or combustible liquids at temperatures above their flashpoint, by dipping, coating, or other means. (FPN): For further information regarding safeguards for these processes, such as fire protection, posting of warning signs, and maintenance, see Spray Application Using Flammable and Combustible Materials, NFPA 33-1989 (ANSI), and Dipping and Coating Processes Using Flammable or Combustible Liquids, NFPA 34-1989 (ANSI). For additional information regarding ventilation, see Blower and Exhaust Systems for Air Conveying of Materials, NFPA 91-1992. 516-2. Classification of Locations. Classification is based on dangerous quantities of flammable vapors, combustible mists, residues, dusts or deposits. (a) Class I or Class II, Division 1 Locations. The following spaces shall be considered Class I or Class II, Division 1 locations, as applicable. (1)* The interiors of spray booths and rooms except as specifically provided in Section 516-3(d). (2)* The interior of exhaust ducts. (3)* Any area in the direct path of spray operations. (4)* For dipping and coating operations, all space within a 5-foot (1.52-m) radial distance from the vapor sources extending from these surfaces to the floor. The vapor source shall be the liquid exposed in the process and the drainboard, and any dipped or coated object from which it is possible to measure vapor concentrations exceeding 25 percent of the lower flammable limit at a distance of 1 foot (305 mm), in any direction, from the object. (5)* Pits within 25 feet (7.62 m) horizontally of the vapor source. If pits extend beyond 25 feet (7.62 m) of the vapor source, a vapor stop shall be provided, or the entire pit shall be classified as Class I, Division 1.