Each spray booth and spray room shall have an independent exhaust duct system discharging to the outdoors.
Exceptions:
1. Multiple spray booths having a combined frontal area of 18 square feet (1.67 m
2
) or less are allowed to have a common exhaust where identical spray-finishing material is used in each booth. If more than one fan serves one booth, such fans shall be interconnected so that all fans operate simultaneously.
2. Where treatment of exhaust is necessary for air pollution control or energy conservation, ducts shall be allowed to be manifolded if all of the following conditions are met:
2.1 The sprayed materials used are compatible and will not react or cause ignition of the residue in the ducts.
2.2 Nitrocellulose-based finishing material shall not be used.
2.3. A filtering system shall be provided to reduce the amount of overspray carried into the duct manifold.
2.4. Automatic sprinkler protection shall be provided at the junction of each booth exhaust with the manifold, in addition to the protection required by this chapter.