scope:

This standard establishes minimum requirements for rubber-seated butterfly valve assemblies, 78 in. (2,000 mm) diameter and larger with flanged ends for freshwater having a pH range of 6-12 and a temperature range of 33°-125°F (0.6°-52°C) and 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 fully open fluid velocity of 16 ft/sec (4.9 m/sec) based on nominal valve size.

Body classes. Valves described in this standard are provided in classes25B, 50B, 75B, and 150B.

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 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/sec (4.9 m/sec) inthe 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 service.

Application

This standard can be referenced in specifications for large-diameter rubberseated butterfly valves, which are described by the scope in Sec. 1.1.