Butterfly Valve for Diverse Throttling and On-Off Applications

by | Jun 22, 2015 | Valves, Actuators & Regulators

Jim Cahill

Chief Blogger, Editor

References to the use of butterfly valves date back to James Watt, who:

…made use of a butterfly valve in his steam engine, and the first Mercedes car built around 1901 introduced a butterfly valve in the fuel intake linked to the accelerator pedal.

Wikipedia describes butterfly valves as from:

…a family of valves called quarter-turn valves. In operation, the valve is fully open or closed when the disc is rotated a quarter turn. The “butterfly” is a metal disc mounted on a rod. When the valve is closed, the disc is turned so that it completely blocks off the passageway. When the valve is fully open, the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the fluid. The valve may also be opened incrementally to throttle flow.

The technologies and applications for these valves have not stood still. Recently the Fisher 8590 butterfly valve was announced to combine a single valve platform to a diverse range of throttling and on-off applications. These applications range from severe service and cryogenic applications to temperatures up to 538°C (1000°F).

Emerson’s Ben Fletcher described the Fisher 8590 valve as a new Class 600 (CL600) high-performance butterfly valve designed to combine the best attributes of the Fisher A11 valve with other Fisher valves such as the Fisher 8580 valve. ANSI Class 600 defines maximum allowable non-shock pressure (psig) and temperature ratings for steel pipe flanges and flanged fittings.

Some of the improvements in the 8590 design were in the shaft diameters. These were changed to match Fisher valve shaft diameters, which allow the valve to share packing parts, etc. with other valves. The shaft diameter was increased on a few sizes to enable the valve to meet full Class 600 pressure drop.

The valve is a lugged body design across the CL600 size range of NPS3 – NPS24 [nominal pipe size] and can incorporate a splined shaft that accepts either a spring-and-diaphragm or pneumatic piston actuator. It is also available with either a square or a keyed shaft that combines with handlevers, handwheels or pneumatic piston actuators.

The 8590 valve uses the Fisher style F mounting pad and comes with a spline shaft, which allows Fisher actuators to be mounted directly to the valve. It provides bidirectional shutoff, which means that torque necessary to open and close the valve remains constant regardless of the differential pressure across the disk. Slam-shut conditions are not created as the disk nears its seat, which extends seal life and avoids actuator and piping damage.

You can connect and interact with other valve and actuator experts in the Valves and Actuators groups in the Emerson Exchange 365 community.

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The opinions expressed here are the personal opinions of the authors. Content published here is not read or approved by Emerson before it is posted and does not necessarily represent the views and opinions of Emerson.