[F] 502.6.2 Type IV and V Systems
Type IV and V dry cleaning systems shall be provided with an automatically activated exhaust ventilation system to maintain an air velocity of not less than 100 feet per minute (0.51 m/s) through the loading door when the door is opened.
Exception: Dry cleaning units are not required to be provided with exhaust ventilation where an exhaust hood is installed immediately outside of and above the loading door and operates at an airflow rate as follows:
Q = Flow rate exhausted through the hood, cubic feet per minute.
ALD = Area of the loading door, square feet.