scope:

This standard establishes minimum requirements for rubber-seated butterfly valve assemblies that are 78 in. (2,000 mm) and larger in diameter with flanged ends suitable for fresh and reclaimed water having a pH range from 6 to 12 and a temperature range from 33 to 125°F (0.6 to 52°C), and suitable for a maximum steady-state fluid working pressure of 250 psig (1,724 kPa [gauge]), a maximum steady-state differential pressure of 250 psi (1,724 kPa), and a maximum full-open fluid velocity of 16 ft/s (4.9 m/s) based on nominal valve size in classes as defined in Sec. 1.1.1 and Sec. 1.1.2.

Body classes. Valves described in this standard are provided in classes 25B, 50B, 75B, 150B, and 250B.

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 the maximum steady-state differential pressure, in pounds per square inch for which the valve is designed. The designation "B" defines the flow-rate capability of the valve in the fully open position. "B" valve assemblies are rated for a maximum velocity of 16 ft/s (4.9 m/s) in the piping section upstream of the valve.

Purpose

The purpose of this standard is to provide the minimum requirements for large-diameter flanged rubber-seated butterfly valve assemblies, suitable for freshwater and reclaimed water service.