(a) Unless suitable ventilated spray booths are used for all finishing operations, finishing rooms shall be continuously ventilated mechanically when in use. Ventilation shall be adequate to prevent fire and health hazards and the provisions therefor shall be subject to the approval of the Fire Chief and the Commissioner of Air Pollution Control. Ventilation shall be such that the percentage of flammable vapor present in any room or exhaust duct at anytime shall not exceed one-fifth (1/5) the lower explosive limit and that toxicity will be reduced by dilution to a safe concentration.
(b) Exhaust outlets in finishing rooms shall be located at the level where flammable vapors accumulate and generally not more than five (5) feet above the floor level, and shall discharge directly outside the building in an approved location. Stacks and ducts shall be of incombustible material and constructed so that there will be no leakage of flammable vapor therefrom. Exhaust ducts of metal shall be constructed of not lighter than twenty (20) U.S. gauge. Exhaust ducts shall be kept not less than six (6) inches from combustible surfaces and shall have approved incombustible ventilating thimbles where passing through combustible floor, wall or roof construction. Where such exhaust ducts extend through other stories of a building, they shall be enclosed with incombustible enclosures having a fire resistance rating of not less than two (2) hours. The discharge outlets of exhaust ducts shall be located so that the discharge of vapors or residue therefrom or, in the event of fire, the discharge of flame, hot gases or smoke, shall not create a hazardous fire, fume or smoke condition or nuisance. All such exhaust systems shall be independent of all other ventilating systems and shall conform to the applicable provisions of Sections 3155.75 to 3155.77.
(c) So far as practicable, all exhaust ducts shall be installed without ledges or crevices in which paint residue may lodge. Provisions shall be made to permit cleaning the interiors of such exhaust ducts. Such provisions shall include access openings at the bottom of every vertical riser and access openings, spaced not more than twenty (20) feet on centers, in horizontal sections.
(Ord. No. 991-49. Passed 6-27-49, eff. 6-27-49)