Chapter 5, Section 511.2.1, is hereby deleted in its entirety and the following provisions shall be substituted therefor:

The air velocity through any duct shall be not more than 2,500 feet per minute nor less than 500 feet (152.4 m) per minute.

Exception: Transition duct sections shall be permitted to be connected to hoods and exhaust fans that do not meet this velocity; provided, that they do not exceed three (3) feet (0.92 m) in length and do not contain traps for grease.