Fisher GX Control Valve Update

20131001-085540.jpgEmerson’s Kaleb Pergande, in the Fisher sliding stem valve team, provided an update on the Fisher GX Control Valve. His abstract:

Just as the Fisher easy-e valve line has evolved over decades of service, so too has the GX control valve. During its first decade of service the GX platform has been rounded out to meet demanding customer needs. This update will cover recent GX enhancements such as; severe service trim, high cycle qualification, expanded supply ranges, actuation optimization, and, most recently, high temperature capability for the GX 3-way and electric actuation mounting compatibility. These improvements expand the GX’s coverage, providing a compact and reliable solution in broad range of applications.

He opened with an overview of the GX platform. Its evolution over the past decade has been driven by end-user feedback to suuport a broad range of applications. The enhancements have improved flexibility while retaining its core design principles.

The valve has a rugged, compact design with the actuator selection being automatic. It was built to support 1-3 week lead times on standard constructions and is a general service valve.

Some design capabilities include compact, multi-spring actuator, stainless steel casing, integrated positioner mounting, self-aligning threaded seat ring, misalignment protection on the sliding stem, ENVIRO-SEAL live-loaded packing system, and port-guided trim.

Important feedback from end users was to have part interchangeability across multiple sizes of valves Body sizes range from 1/2″ to 6″ . Materials of construction include carbon steel and stainless steel. The packing system meets the major international emissions standards.

Some of the key enhancements over time include severe service trim for applications where the fluid flow generates aerodynamic valve noise to provide up to an 18 dba noise reduction.

Another extension to the GX platform is pressure swing adsorption (PSA) for applications which demand high cycles and tight, bi-directional shutoff to support a million cycles of operation while maintaining Class VI shutoff.

Further into the development of the GX platform the actuator was optimized to fit a smaller weight and space. Height, weight, and operating envelop were reduced across the different GX control valve sizes. The actuator springs are designed to support high-cycle applications.

In 2009, a 3-way GX control valve was introduced with carbon steel and stainless steel materials of construction. The same actuator and packing design is used as in the 2-way valves. 3D modeling was performed up front to verify the design and avoid issues such as flow swirl which may have not been seen until the initial prototypes were built.

For many high temperature applications such as hot oil heat exchangers a yoke extension was designed to increase the temperature capability to 371 degC (700 degF).

Kaleb closed his update on the enhancements describing the addition of electric actuation. The yoke was designed to comply with ISO 5210 flange type F7 which is a common specification for electric actuators.

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