If a room or department in any factory is to process, brew, or mill food or beverages, and a large floor area is occupied by permanently installed, closed tanks, vats or food processing equipment (thus reducing occupiable floor space), the minimum ventilating requirements specified in Table 18-28-403.3 shall be adjusted and determined to conform to the following requirements.
1. Rooms in which the total area of the ventilating opening is 4 percent or more than the "employees" net work floor area shall conform to the requirements for natural ventilation.
2. Rooms which have no ventilation opening or in which the total area of the ventilation opening is less than four percent of the "employees" net work floor area shall provide supply and exhaust of 1.2 cfm per square foot of net work floor area.