Understanding Torque for Quarter-Turn Valves

Valve manufacturers publish torques for their merchandise in order that actuation and mounting hardware may be properly selected. However, published torque values usually characterize only the seating or unseating torque for a valve at its rated strain. While these are essential values for reference, revealed valve torques do not account for precise set up and operating traits. In order to find out the precise working torque for valves, it’s necessary to understand the parameters of the piping systems into which they’re installed. Factors such as set up orientation, path of flow and fluid velocity of the media all impression the precise working torque of valves.
Trunnion mounted ball valve operated by a single appearing spring return actuator. Photo credit: Val-Matic
The American Water Works Association (AWWA) publishes detailed data on calculating working torques for quarter-turn valves. This data appears in AWWA Manual M49 Quarter-Turn Valves: Head Loss, Torque, and Cavitation Analysis. Originally printed in 2001 with torque calculations for butterfly valves, AWWA M49 is currently in its third edition. In addition to info on butterfly valves, the current version additionally contains working torque calculations for other quarter-turn valves including plug valves and ball valves. Overall, this guide identifies 10 components of torque that may contribute to a quarter-turn valve’s operating torque.
Example torque calculation abstract graph
The first AWWA quarter-turn valve normal for 3-in. via 72-in. butterfly valves, C504, was published in 1958 with 25, 50 and 125 psi stress lessons. In 1966 the 50 and 125 psi pressure classes have been elevated to 75 and one hundred fifty psi. The 250 psi strain class was added in 2000. The 78-in. and bigger butterfly valve commonplace, C516, was first published in 2010 with 25, 50, seventy five and one hundred fifty psi strain classes with the 250 psi class added in 2014. The high-performance butterfly valve commonplace was printed in 2018 and contains 275 and 500 psi stress lessons as nicely as pushing the fluid move velocities above class B (16 ft per second) to class C (24 feet per second) and sophistication D (35 ft per second).
The first AWWA quarter-turn ball valve commonplace, C507, for 6-in. through 48-in. ball valves in a hundred and fifty, 250 and 300 psi strain courses was printed in 1973. In 2011, dimension range was increased to 6-in. by way of 60-in. These valves have always been designed for 35 ft per second (fps) maximum fluid velocity. The velocity designation of “D” was added in 2018.
Although the Manufacturers Standardization Society (MSS) first issued a product standard for resilient-seated cast-iron eccentric plug valves in 1991, the first a AWWA quarter-turn valve standard, C517, was not printed until 2005. เครื่องวัดแรงดันเกจที่นิยมใช้ was three in. via seventy two in. with a 175
Example butterfly valve differential stress (top) and move fee management windows (bottom)
strain class for 3-in. through 12-in. sizes and 150 psi for the 14-in. by way of 72-in. The later editions (2009 and 2016) haven’t elevated the valve sizes or pressure courses. The addition of the A velocity designation (8 fps) was added in the 2017 version. This valve is primarily utilized in wastewater service where pressures and fluid velocities are maintained at decrease values.
The want for a rotary cone valve was recognized in 2018 and the AWWA Rotary Cone Valves, 6 Inch Through 60 Inch (150 mm by way of 1,500 mm), C522, is beneath growth. This normal will embody the same one hundred fifty, 250 and 300 psi stress lessons and the same fluid velocity designation of “D” (maximum 35 ft per second) as the present C507 ball valve standard.
In general, all the valve sizes, circulate rates and pressures have increased since the AWWA standard’s inception.
AWWA Manual M49 identifies 10 components that affect operating torque for quarter-turn valves. These components fall into two basic categories: (1) passive or friction-based parts, and (2) active or dynamically generated elements. Because valve producers can’t know the precise piping system parameters when publishing torque values, published torques are usually restricted to the five elements of passive or friction-based parts. These include:
Passive torque elements:
Seating friction torque
Packing friction torque
Hub seal friction torque
Bearing friction torque
Thrust bearing friction torque
The different five parts are impacted by system parameters corresponding to valve orientation, media and move velocity. The components that make up lively torque embody:
Active torque elements:
Disc weight and middle of gravity torque
Disc buoyancy torque
Eccentricity torque
Fluid dynamic torque
Hydrostatic unbalance torque
When contemplating all these numerous lively torque parts, it is attainable for the precise operating torque to exceed the valve manufacturer’s published torque values.
Although quarter-turn valves have been used within the waterworks business for a century, they are being uncovered to larger service strain and circulate rate service situations. Since the quarter-turn valve’s closure member is always positioned within the flowing fluid, these larger service circumstances instantly influence the valve. Operation of those valves require an actuator to rotate and/or maintain the closure member throughout the valve’s physique because it reacts to all the fluid pressures and fluid move dynamic conditions.
In addition to the elevated service conditions, the valve sizes are additionally increasing. The dynamic conditions of the flowing fluid have higher effect on the larger valve sizes. Therefore, the fluid dynamic results turn into more important than static differential stress and friction loads. Valves may be leak and hydrostatically shell examined during fabrication. However, the total fluid flow situations cannot be replicated before site set up.
Because of the pattern for elevated valve sizes and increased working situations, it’s increasingly necessary for the system designer, operator and owner of quarter-turn valves to higher perceive the impact of system and fluid dynamics have on valve choice, development and use.
The AWWA Manual of Standard Practice M forty nine is devoted to the understanding of quarter-turn valves together with working torque requirements, differential stress, flow conditions, throttling, cavitation and system set up variations that directly influence the operation and successful use of quarter-turn valves in waterworks techniques.
The fourth version of M49 is being developed to incorporate the modifications in the quarter-turn valve product standards and installed system interactions. A new chapter might be devoted to strategies of control valve sizing for fluid flow, pressure control and throttling in waterworks service. This methodology contains explanations on the use of stress, flow price and cavitation graphical home windows to supply the consumer a thorough picture of valve performance over a spread of anticipated system working circumstances.
Read: New Technologies Solve Severe Cavitation Problems
About the Authors
Steve Dalton started his profession as a consulting engineer within the waterworks business in Chicago. He joined Val-Matic in 2011 and was appointed president of Val-Matic in May 2021, following the retirement of John Ballun. Dalton previously labored at Val-Matic as Director of Engineering. He has participated in standards creating organizations, including AWWA, MSS, ASSE and API. เกจ์วัดแก๊สหุงต้ม holds BS and MS degrees in Civil and Environmental Engineering together with Professional Engineering Registration.
John Holstrom has been concerned in quarter-turn valve and actuator engineering and design for 50 years and has been an active member of each the American Society of Mechanical Engineers (ASME) and the American Water Works Association (AWWA) for more than 50 years. He is the chairperson of the AWWA sub-committee on the Manual of Standard Practice, M49, “Quarter-Turn Valves: Head Loss, Torque and Cavitation Analysis.” He has additionally labored with the Electric Power Research Institute (EPRI) in the development of their quarter-turn valve performance prediction strategies for the nuclear energy business.

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