For spray application operations conducted in an enclosed spray booth or spray room with openings for product conveyance, the ventilation system shall be designed, installed and maintained so that the average air velocity into the spray booth through openings is not less than 100 feet per minute (0.51 m/s).
- For fixed or automated electrostatic spray application equipment, the average air velocity into the spray booth through all openings shall be not less than 50 feet per minute (0.25 m/s).
- Where methods are used to reduce cross drafts that can draw vapors and overspray through openings from the spray booth or spray room, the average air velocity into the spray booth or spray room shall be that necessary to capture and confine vapors and overspray to the spray booth or spray room.
- 28 gauge sheet metal on 1/4 inch (305 mm) insulating millboard 12 inches
- 28 gauge sheet metal on 1/8 inch insulating millboard spaced out 1 inch (254 mm) on noncombustible spacers 9 inches (230 mm).
- 22 gauge sheet metal on 1 inch rockwool bats reinforced with wire mesh or the equivalent 3 inches (76 mm).
- Any other approved material of equal or greater fire-resistance.