This standard covers 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 to 10 and a temperature range from 33 to 125F (0.6 to 52C). This standard covers rubber-seated butterfly valves suitable for a maximum steady-state fluid working pressure of 150 psig (1,034 kPa [gauge]), a maximum steady-state differential pressure of 150 psi (1,034 kPa), and a maximum velocity of 16 ft/s (4.9 m/s). 1.1.1 Body types, classes, and sizes. Valves covered by this standard are furnished in four body types and in classes as follows: 1.1.1.1 Wafer valves. Class 150B, in sizes 3-20 in. (75-500 mm); 1.1.1.2 Short-body flanged valves. All classes, in sizes 3-72 in. (75-1,800 mm). 1.1.1.3 Long-body flanged valves. Class 75A, class 75B, class 150A, and class 150B, in sizes 3-72 in. (75-1,800 mm); and 1.1.1.4 Mechanical-joint-end valves. Class 150B, in sizes 3-24 in. (75-600 mm), and all classes in sizes 30-48 in. (750-1,200 mm). 1.1.2 Definition of classification. In each case, the numeric designation represents the pressure rating (the maximum steady-state fluid working pressure, in pounds-per-square-inch gauge) and also the maximum steady-state differential pressure, in pounds per square inch, for which the valve is designed. The designations "A" and "B" define the flow-rate capabilities with the valve in the fully open position. "A" valves are rated for a maximum velocity of 8 ft/s (2.4 m/s), and "B" valves are rated for a maximum velocity of 16 ft/s (4.9 m/s) in the piping section upstream of the valve. Major revisions included in this edition of AWWA C504 consist of the following: Appendix A, Suggested Method for Calculating Torques Required to Operate Butterfly Valves, was deleted; Soft metrication was implemented; Scope--temperature and pH ranges were added; Section 2, Materials: Lead content of wetted parts was limited, 70-50-05 ductile iron was added, Corrosion-resistant metals were defined; Section 3, General Design: Connection requirements were clarified and expanded, Section 3.5.3.1 was expanded to allow a nickel-alloy seat and to require a minimum seat width, Section 3.5.3.3 was expanded to include a welding process to attach a mating seat, Section 3.7.4.2 was expanded to permit the use of engineered plastic materials, Section 3.8.1 was expanded to include the basis for actuator sizing, Section 3.8.6: Requirements for electric actuators are now included in AWWA C540, Section 3.8.7: Requirements for cylinder actuators are now included in AWWA C540; and Former appendix B is now appendix A.