OSHA Regulations for Spraying Flammable and Combustible Liquids 1. The spraying of flammable and combustible liquids is strictly regulated because of the high risk of fire. OSHA regulations on Spray Finishing Using Flammable and Combustible Liquids are found in CFR 1910.107. 2. According to OSHA, a spraying area is "any area in which dangerous quantities of flammable vapors or mists or combustible residues are present due to operation of spraying operations". A spray booth is "a power-ventilated structure provided to enclose or accommodate a spraying operation to confine and limit the escape of spray vapor and residue and to safely conduct or direct them to an exhaust system". 3. According to CFR 1910.107(b), spray booths must meet the following standards: - They may be constructed of aluminum or other substantially noncombustible materials for intermittent or low volume spraying; otherwise of steel or concrete masonry. - The interior must be smooth, and floors noncombustible or covered with a noncombustible material that is easily and safely cleaned. - Distribution or baffle plates must be noncombustible and removable. - There must be maintenance procedures to ensure replacement of dry type overspray filters when the booth face velocity drops below 100 feet/minute (fpm). Gauges must be installed as an alarm to indicate when the face velocity is inadequate due to filter overloading. The filters must be noncombustible or have a combustible rating less than 2, according to Underwriters Laboratory. Discarded filters must be removed or placed in water- filled metal containers. - There must be automatic sprinklers both up and downstream of the filters. - If the booth opening is greater than 9 square feet, then metal deflectors or curtains at least 2.5 inches long must be placed at the upper, outer edge of the spray booth. - The spray booth must be separated from other operations by at least 3 feet or by partitions or walls. - There must be a 3 foot clearance on all sides of the spray booth which is kept free of storage or combustible construction. - When spraying areas are illuminated through transparent panels, only fixed lighting sources can be used, the panels should isolate the spraying area from the lighting area, and the panels should be noncombustible and of such a material or located so that breakage is unlikely. The panels should be located so that any spray residue on the panels does not heat up to a dangerous temperature. 4. Electrical and other sources of ignition are covered in CFR 1910.107(c) : - There shall be no open flames or spark-producing equipment in any spraying area or within 20 feet, unless separated by partitions. - No space heaters, steam pipes or hot surfaces may be located in the spraying area where combustible residues may accumulate. - Unless approved no electrical equipment may be located in any spraying area where combustible residues may accumulate except wiring in rigid conduit or in boxes or fittings containing no taps, splices or terminal connections. - Electrical wiring and equipment in spraying areas not subject to residue accumulation must be explosion-proof and be approved by the National Electrical Code for Class I Group D locations, and meet other requirements for Class I Division 1 Hazardous Locations. - Electrical equipment and wiring outside but within 20 feet of a spraying area must not produce sparks, and must meet requirements for Class I Division 2 Hazardous Locations. - Electric lamps outside the spraying area but within 20 feet and not separated by a partition must be totally enclosed, and protected from mechanical injury ( ie shatterproof and in safe location). - Portable lamps shall not be used during spraying, and must be approved for a Class I hazardous location for use during cleanup. - All metal parts of spray booth, ducts, etc. shall be grounded. - Airless high pressure spray guns and conductive objects being sprayed should be grounded. 5. CFR 1910.107(d) covers ventilation to prevent fires and explosions. - Ventilation shall conform to NFPA 91-1967 and this section. - All spraying areas shall be provided with mechanical ventilation during spraying and drying. - Multiple spray booths shall have independent exhaust unless they are using the same materials and having a combined face area less than 18 sq. ft. - Fan blades shall be nonferrous and non-sparking, and there shall be enough clearance between the blade and casing to prevent frictional heating. Bearings shall be self-lubricating or lubricated from outside the duct. - Electric motors shall not be inside the booth or ducts. - Exhaust ducts shall be made of steel, and protected against mechanical damage. There shall be at least 18 inches clearance from unprotected combustible structures around ducts ( 6 inches if ducts have a sprinkler system). - Except for water wash booths, the terminal discharge point of ducts shall be at least 6 feet away from any combustible exterior wall, and no combustible construction or unprotected opening within 25 feet. - The air exhaust shall not be directed so as to contaminate intake air and not recirculated. - Ducts shall have access doors to facilitate cleaning. - There shall be adequate makeup air for the exhaust. - Drying areas shall be ventilated to prevent explosions and shall be considered spraying areas. 6. Storage and handling of flammable and combustible liquids is covered in CFR 1910.107(e): - Storage and handling must conform to CFR 1910.106. - Only the minimum amount of flammable and combustible liquids ordinarily needed for one day's operation may be stored in the vicinity of a spraying operation. - Storage must be in original, closed containers or safety cans. - Transfer of flammable and combustible liquids must be done in suitable mixing area or in spraying area with ventilation system operating. Precautions must be taken against sparks and sources of ignition. Transfer from containers larger than 60 gallons must be done with approved pumps. - Spraying containers must meet certain standards. - Piping and hoses for spraying must have a shutoff valve at the connection, automatic pressure release for pumps, be properly bonded and grounded, and be regularly inspected. - Pump discharge line must have relief valve discharging to pump suction or a safe location. - There must be proper bonding and grounding when transferring from one container to another. 7. Fire protection is covered in CFR 1910.107(f): - If the building is sprinklered, the spraying area must conform to NFPA 13-1968 dealing with extra hazard occupancies. - Sprinkler heads must be kept clean. - Fire extinguishers must be located near all spraying areas. 8. Operations and maintenance is covered in CFR 1910.107(g): - Spraying must occur only in predetermined spraying areas. - The spraying area must be kept clean of deposits, using non- sparking tools for cleaning. - Spraying residues must be immediately removed from premises. - Solvent- and paint-soaked rags must be kept in approved metal containers, which are emptied daily. - Clothing used in spraying must not be kept overnight on premises, except in metal lockers. - Cleaning solvents must have a flash point greater then 100 F (ie combustible). For cleaning spray nozzles and equipment, lower flash solvents may be used (but not lower than material being sprayed) if cleaning is done inside spray booth with ventilation in operation. - Incompatible materials shall not be alternately used in a spray booth without cleaning residue first. - No smoking signs shall be displayed in all spraying areas and paint storage rooms. 9. Electrostatic hand-spraying equipment is covered in CFR 1910.107(i). - Equipment shall be approved, with a maximum temperature of 150 F, and high voltage circuits shall not cause sparks or shocks. - Electrical support equipment shall be located outside the spraying area. - The spray gun shall be grounded; the handle shall be grounded so that the operator only contacts the grounded handle. - All conductive objects in the spraying area shall be grounded, including paints cans, waste cans, etc. - The spray gun shall be interlocked with ventilation fans. (c) Copyright Center for Safety in the Arts, 1988.