The Fisher A31A is a high-performance butterfly valve featuring a keyed shaft for on/off service. A31A is available in NPS 14 through 24, CL150 and CL300. This valve is available in either a flangeless wafer-style design, or a single-flange (lugged) body. The Cryogenic version of this valve is available in NPS 3 through 24.
Features & Benefits
Economical Tight Shutoff—The pressure-assisted seal design provides tight shutoff and permits the use of smaller, less expensive actuators in applications requiring full ASME B16.34 shutoff capabilities.
Excellent Shutoff Integrity—Concentric rotation helps to ensure that the valve disc remains in the closed position in spite of line pressure surges or actuator failure.
True Bi-directional Shutoff Performance— 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 A31A valve. 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.
Ease of Maintenance—Interchangeability of all parts including shafts and discs simplifies service and reduces maintenance costs.
Improved Environmental 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.
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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