Valve producers publish torques for his or her products in order that actuation and mounting hardware could be correctly chosen. However, printed torque values typically symbolize only the seating or unseating torque for a valve at its rated pressure. While these are necessary values for reference, revealed valve torques do not account for precise installation and operating traits. In order to determine the actual working torque for valves, it’s needed to grasp the parameters of the piping methods into which they are put in. Factors corresponding to installation orientation, path of flow and fluid velocity of the media all influence the actual working torque of valves.
Trunnion mounted ball valve operated by a single performing spring return actuator. Photo credit score: Val-Matic
The American Water Works Association (AWWA) publishes detailed data on calculating operating torques for quarter-turn valves. This data seems in AWWA Manual M49 Quarter-Turn Valves: Head Loss, Torque, and Cavitation Analysis. Originally revealed in 2001 with torque calculations for butterfly valves, AWWA M49 is presently in its third edition. In addition to data on butterfly valves, the present edition also contains operating torque calculations for different quarter-turn valves together with 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
AWWA QUARTER-TURN VALVE HISTORY
The first AWWA quarter-turn valve standard for 3-in. through 72-in. butterfly valves, C504, was revealed in 1958 with 25, 50 and 125 psi stress courses. In 1966 the 50 and a hundred twenty five psi strain courses were increased to seventy five and 150 psi. The 250 psi pressure class was added in 2000. The 78-in. and larger butterfly valve standard, C516, was first printed in 2010 with 25, 50, seventy five and a hundred and fifty psi strain lessons with the 250 psi class added in 2014. The high-performance butterfly valve standard was published in 2018 and includes 275 and 500 psi strain courses in addition to pushing the fluid circulate velocities above class B (16 toes per second) to class C (24 feet per second) and sophistication D (35 ft 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 lessons was printed in 1973. In 2011, size vary was increased to 6-in. by way of 60-in. These valves have at all times 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 normal for resilient-seated cast-iron eccentric plug valves in 1991, the primary a AWWA quarter-turn valve commonplace, C517, was not revealed till 2005. The 2005 dimension vary was 3 in. via seventy two in. with a one hundred seventy five
Example butterfly valve differential strain (top) and flow fee management windows (bottom)
strain class for 3-in. through 12-in. sizes and one hundred fifty psi for the 14-in. through 72-in. The later editions (2009 and 2016) have not elevated the valve sizes or pressure classes. The addition of the A velocity designation (8 fps) was added in the 2017 version. This valve is primarily utilized in wastewater service the place pressures and fluid velocities are maintained at lower values.
The need for a rotary cone valve was recognized in 2018 and the AWWA Rotary Cone Valves, 6 Inch Through 60 Inch (150 mm via 1,500 mm), C522, is beneath improvement. เกจวัดแรงดันน้ำ will embody the identical one hundred fifty, 250 and 300 psi pressure courses and the identical fluid velocity designation of “D” (maximum 35 toes per second) as the current C507 ball valve normal.
In common, all the valve sizes, circulate rates and pressures have increased for the rationale that AWWA standard’s inception.
COMPONENTS OF OPERATING TORQUE
AWWA Manual M49 identifies 10 elements that have an effect on working torque for quarter-turn valves. These components fall into two common categories: (1) passive or friction-based parts, and (2) active or dynamically generated elements. Because valve producers cannot know the precise piping system parameters when publishing torque values, revealed torques are typically restricted to the 5 components of passive or friction-based components. These embrace:
Passive torque components:
Seating friction torque
Packing friction torque
Hub seal friction torque
Bearing friction torque
Thrust bearing friction torque
The other five elements are impacted by system parameters such as valve orientation, media and circulate velocity. The elements that make up lively torque embrace:
Active torque components:
Disc weight and center of gravity torque
Disc buoyancy torque
Eccentricity torque
Fluid dynamic torque
Hydrostatic unbalance torque
When contemplating all these numerous lively torque elements, it’s possible for the precise operating torque to exceed the valve manufacturer’s published torque values.
WHY IS M49 MORE IMPORTANT TODAY?
Although quarter-turn valves have been used in the waterworks business for a century, they’re being exposed to higher service stress and move fee service circumstances. Since the quarter-turn valve’s closure member is at all times situated in the flowing fluid, these larger service conditions directly impact the valve. Operation of these valves require an actuator to rotate and/or maintain the closure member within the valve’s body as it reacts to all of the fluid pressures and fluid circulate dynamic situations.
In addition to the increased service situations, the valve sizes are also growing. The dynamic conditions of the flowing fluid have greater effect on the bigger valve sizes. Therefore, the fluid dynamic effects become extra essential than static differential pressure and friction masses. Valves can be leak and hydrostatically shell tested during fabrication. However, the full fluid circulate situations cannot be replicated before website installation.
Because of เกจวัดแรงกด for elevated valve sizes and elevated working circumstances, it’s more and more important for the system designer, operator and proprietor of quarter-turn valves to raised understand the influence of system and fluid dynamics have on valve choice, development and use.
The AWWA Manual of Standard Practice M 49 is devoted to the understanding of quarter-turn valves including working torque requirements, differential pressure, move situations, throttling, cavitation and system installation differences that instantly influence the operation and successful use of quarter-turn valves in waterworks techniques.
AWWA MANUAL OF STANDARD PRACTICE M49 4TH EDITION DEVELOPMENTS
The fourth edition of M49 is being developed to incorporate the adjustments in the quarter-turn valve product standards and put in system interactions. A new chapter shall be dedicated to strategies of management valve sizing for fluid flow, stress control and throttling in waterworks service. This methodology contains explanations on using pressure, move price and cavitation graphical home windows to provide the user a radical picture of valve performance over a range of anticipated system operating conditions.
Read: New Technologies Solve Severe Cavitation Problems
About the Authors
Steve Dalton started his profession as a consulting engineer in the waterworks industry 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 worked at Val-Matic as Director of Engineering. He has participated in requirements creating organizations, including AWWA, MSS, ASSE and API. Dalton holds BS and MS levels in Civil and Environmental Engineering together 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 energetic member of both the American Society of Mechanical Engineers (ASME) and the American Water Works Association (AWWA) for greater 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 methods for the nuclear power trade.
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