The Fisher A31D is a double-flange high-performance butterfly valve featuring either a splined drive shaft or a keyed drive shaft for either throttling or on/off service. A31D is available in NPS 3 through 24, CL150 and CL300.
Features & Benefits
Excellent Shutoff Integrity-- The pressure-assisted seal design provides tight shutoff and permits the use of smaller actuators in applications requiring full ASME B16.34 shutoff capabilities.
True Bi-directional Shutoff Performance-- A31D valve design helps to ensure that the torque necessary to open and close the valve is the same regardless of the direction in which the differential pressure is applied.
Safety-- Shaft-blowout protection is designed into the A31D valve. For NPS 3 through 12 valves, the packing follower and an anti-blowout follower hold an anti-blowout gland securely around the valve shaft. Under the anti-blowout gland, a formed wire ring around the shaft completes the protection design. For NPS 14 through 24 valves, the anti-blowout gland fits securely over the valve shaft which has been turned down to form a circumferential shoulder that contacts the anti-blowout gland.
Excellent Emissions Capabilities-- The optional ENVIRO-SEAL™ packing system is designed with improved sealing, guiding, and loading force transmission. The ENVIRO-SEAL packing system can control emissions to below the EPA (Environmental Protection Agency) limit of 100 ppm (parts per million) for valves.
Shaft Versatility-- This valve will meet your actuator needs with a choice of splined or keyed shaft connections.
Sour Service Capability-- Trim and bolting materials are available for applications involving sour liquids and gases. These constructions comply with NACE MR0175-2002, MR0103, and MR0175/ISO 15156.
Reliable Flange Gasketing Surface-- Seal retainer screws are located so there is no interference with the sealing function of either flat sheet or spiral wound line flange gaskets.
Easy Installation-- The valve body self-centers on the line flange bolts as a fast, accurate means of centering the valve in the pipeline.
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