Air flow from the customer area into the service area may be through grilles in the machine front or through grilles or openings in the partition. Grilles or openings in the partition should be sized on the basis of 500 CFM per square foot of net grille area and should be placed as close to the machines as possible. As an example, the use of a thirty-inch by six-inch grille located directly over each machine or drum is recommended.
(1974 Code § 7.235)