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Updated On: October 22, 2013
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: 188.8.131.52 Wafer valves. Class 150B, in sizes 3-20 in. (75-500 mm); 184.108.40.206 Short-body flanged valves. All classes, in sizes 3-72 in. (75-1,800 mm). 220.127.116.11 Long-body flanged valves. Class 75A, class 75B, class 150A, and class 150B, in sizes 3-72 in. (75-1,800 mm); and 18.104.22.168 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.