R 325.17709 Ventilation exhaust ducts and deodorizing vents; size; sealing; discharge height.

Rule 709. (1) Ventilation exhaust ducts and deodorizing vents in dry cleaning establishments shall be sized to maintain the required air flow. The joints of the ducts shall be effectively sealed, soldered, or taped. The ducts shall extend to a minimum height of 5 feet above the roofline and a minimum of 25 feet from any air intake unit or opening and shall extend above any adjacent parapet wall or above adjacent buildings, whichever is higher. The ducts shall be equipped with a vertical discharge cap. (2) Where deodorizing vents are connected to a common duct, the main duct shall be sized to maintain rated airflow from all the dry cleaning machines and shall be extended as required by subrule (1) of this rule. Backdraft dampers in individual deodorizing stacks may be required by the department. (3) The exit location of ventilation ducts and deodorizing system vents shall be installed so as to prevent the entry of solvent-contaminated air into the make-up air supply or other air intakes or combustion air systems in the dry cleaning establishment.