scope:

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 and reclaimed water having a pH range from 6-12 and a temperature range from 33°-125°F (0.6°-52°C). This standard covers rubberseated 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 full open fluid velocity of 16 ft/sec (4.9 m/sec) based on nominal valve size.

Body types, classes, and sizes. Valves described in this standard are provided in four body types and in classes as follows: 

Wafer valves. Class 150B, in sizes 3 in.-20 in. (75 mm-500 mm).

Short-body and long-body flanged valves. Class 25A, Class 25B, Class 75A, Class 75B, Class 150A, and Class 150B, in sizes 3 in.-72 in. (75 mm-1,800 mm), and Class 250B in sizes 3 in.-48 in. (75 mm-1,200 mm). 

Mechanical-joint-end valves. Class 150B and Class 250B, in sizes 3 in.-24 in. (75 mm-600 mm), and Class 25A, Class 25B, Class 75A, Class 75B, Class 150A, Class 150B, and Class 250B, in sizes 30 in.-48 in. (750 mm-1,200 mm).

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. 

A and B designations. The designations A and B define the flowrate capabilities with the valve in the fully open position. Valves designated A are rated for a maximum velocity of 8 ft/sec (2.4 m/sec), and B valves are rated for a maximum velocity of 16 ft/sec (4.9 m/sec) in the piping section upstream of the valve.

Purpose

The purpose of this standard is to provide the minimum requirements for rubber-seated butterfly valves suitable for freshwater service.