This standard establishes minimum requirements for rubber-seated butterfly valves, 3 in. (75 mm) through 72 in. (1,800 mm) in diameter, with various body and end types, for fresh water having a pH range from 6-12 and a temperature range from 33º-125ºF (0.6º-52ºC). This standard covers rubber-seated butterfly valves suitable for a maximum steady-state fluid working pressure of 250 psig (1,723 kPa), a maximum steady-state differential pressure of 250 psi (1,723 kPa), and a maximum fully open fluid velocity of 16 ft/sec (4.9 m/sec) based on nominal valve size. The major revisions made to the standard in this edition include the following: permeation language was moved to the Foreword under Special Issues, Sec. II.C; and, new requirements were provided for mechanical-joint-end valves.