An air chamber that is installed in a fixture supply shall be 12 inches (304.8 mm) in length and the same diameter as the fixture supply, or an air chamber with an equivalent volume may be used. An air chamber that is installed in a riser shall be 12 inches (304.8 mm) in length and at least the same diameter as the riser.
(Added Coun. J. 12-14-22, p. 58278, Art. VI, § 9)