Understanding Torque for Quarter-Turn Valves

Valve manufacturers publish torques for their merchandise in order that actuation and mounting hardware could be correctly chosen. However, revealed torque values usually represent solely the seating or unseating torque for a valve at its rated pressure. While these are important values for reference, printed valve torques do not account for precise set up and operating characteristics. In order to discover out the precise working torque for valves, it’s essential to understand the parameters of the piping techniques into which they’re put in. Factors such as installation orientation, direction of circulate and fluid velocity of the media all influence the precise operating 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 information on calculating operating torques for quarter-turn valves. เกจวัดแก๊ส 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 version. In addition to information on butterfly valves, the current version also consists of working torque calculations for different quarter-turn valves together with plug valves and ball valves. Overall, this guide identifies 10 components of torque that can contribute to a quarter-turn valve’s working torque.
Example torque calculation summary graph
The first AWWA quarter-turn valve commonplace for 3-in. via 72-in. butterfly valves, C504, was revealed in 1958 with 25, 50 and one hundred twenty five psi pressure courses. In เครื่องมือตรวจวัดความดันเลือดเรียกว่า and one hundred twenty five psi pressure lessons were increased to seventy five and one hundred fifty psi. The 250 psi strain class was added in 2000. The 78-in. and larger butterfly valve commonplace, C516, was first printed in 2010 with 25, 50, 75 and 150 psi pressure courses with the 250 psi class added in 2014. The high-performance butterfly valve standard was printed in 2018 and contains 275 and 500 psi strain classes as well as pushing the fluid circulate velocities above class B (16 feet per second) to class C (24 feet per second) and class D (35 feet per second).
The first AWWA quarter-turn ball valve standard, C507, for 6-in. by way of 48-in. ball valves in 150, 250 and 300 psi strain courses was published in 1973. In 2011, dimension vary was elevated to 6-in. via 60-in. These valves have all the time been designed for 35 ft per second (fps) most fluid velocity. The velocity designation of “D” was added in 2018.
Although the Manufacturers Standardization Society (MSS) first issued a product commonplace for resilient-seated cast-iron eccentric plug valves in 1991, the first a AWWA quarter-turn valve normal, C517, was not published until 2005. The 2005 measurement vary was 3 in. through seventy two in. with a a hundred seventy five
Example butterfly valve differential strain (top) and flow price management home windows (bottom)
pressure class for 3-in. via 12-in. sizes and one hundred fifty psi for the 14-in. via 72-in. The later editions (2009 and 2016) haven’t elevated the valve sizes or strain courses. The addition of the A velocity designation (8 fps) was added within the 2017 version. This valve is primarily used in wastewater service where pressures and fluid velocities are maintained at decrease values.
The want for a rotary cone valve was acknowledged in 2018 and the AWWA Rotary Cone Valves, 6 Inch Through 60 Inch (150 mm by way of 1,500 mm), C522, is under growth. This commonplace will embody the identical a hundred and fifty, 250 and 300 psi strain courses and the identical fluid velocity designation of “D” (maximum 35 feet per second) as the current C507 ball valve commonplace.
In basic, all of the valve sizes, move charges and pressures have increased because the AWWA standard’s inception.
AWWA Manual M49 identifies 10 parts that affect operating torque for quarter-turn valves. These elements fall into two basic categories: (1) passive or friction-based parts, and (2) energetic or dynamically generated parts. Because valve producers cannot know the precise piping system parameters when publishing torque values, printed torques are typically restricted to the five components of passive or friction-based components. These embody:
Passive torque parts:
Seating friction torque
Packing friction torque
Hub seal friction torque
Bearing friction torque
Thrust bearing friction torque
The different 5 parts are impacted by system parameters corresponding to valve orientation, media and move velocity. The elements that make up active torque include:
Active torque components:
Disc weight and heart of gravity torque
Disc buoyancy torque
Eccentricity torque
Fluid dynamic torque
Hydrostatic unbalance torque
When considering all these varied lively torque parts, it is attainable for the precise working torque to exceed the valve manufacturer’s printed torque values.
Although quarter-turn valves have been used in the waterworks industry for a century, they’re being uncovered to greater service stress and circulate rate service conditions. Since the quarter-turn valve’s closure member is at all times located in the flowing fluid, these greater service circumstances instantly impact the valve. Operation of these valves require an actuator to rotate and/or hold the closure member within the valve’s body because it reacts to all the fluid pressures and fluid circulate dynamic situations.
In addition to the increased service circumstances, the valve sizes are additionally rising. The dynamic circumstances of the flowing fluid have larger effect on the bigger valve sizes. Therefore, the fluid dynamic results become more essential than static differential stress and friction loads. Valves could be leak and hydrostatically shell tested throughout fabrication. However, the complete fluid circulate situations can’t be replicated before site installation.
Because of the development for elevated valve sizes and increased operating circumstances, it is more and more important for the system designer, operator and owner of quarter-turn valves to higher understand the influence of system and fluid dynamics have on valve selection, development and use.
The AWWA Manual of Standard Practice M 49 is devoted to the understanding of quarter-turn valves including working torque necessities, differential stress, circulate circumstances, throttling, cavitation and system set up differences that directly affect the operation and profitable use of quarter-turn valves in waterworks systems.
The fourth edition of M49 is being developed to incorporate the adjustments within the quarter-turn valve product standards and put in system interactions. A new chapter might be devoted to strategies of control valve sizing for fluid circulate, strain management and throttling in waterworks service. This methodology consists of explanations on the use of stress, move fee and cavitation graphical home windows to supply the user an intensive image of valve performance over a range of anticipated system working situations.
Read: New Technologies Solve Severe Cavitation Problems
About the Authors
Steve Dalton started his career as a consulting engineer in 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 beforehand worked at Val-Matic as Director of Engineering. He has participated in standards developing organizations, including AWWA, MSS, ASSE and API. Dalton holds BS and MS degrees in Civil and Environmental Engineering along with Professional Engineering Registration.
John Holstrom has been involved in quarter-turn valve and actuator engineering and design for 50 years and has been an active member of both 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 also labored with the Electric Power Research Institute (EPRI) within the improvement of their quarter-turn valve performance prediction strategies for the nuclear energy business.

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