Understanding Torque for Quarter-Turn Valves

เกจวัดแรงดันลมคือ publish torques for his or her merchandise in order that actuation and mounting hardware may be properly chosen. However, printed torque values often represent only the seating or unseating torque for a valve at its rated stress. While these are essential values for reference, published valve torques do not account for precise set up and operating characteristics. In order to discover out the actual operating torque for valves, it is essential to know the parameters of the piping techniques into which they are put in. Factors corresponding to set up orientation, direction of flow and fluid velocity of the media all impression the actual 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 information 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 at present in its third edition. In addition to data on butterfly valves, the present edition also consists of operating torque calculations for other quarter-turn valves including plug valves and ball valves. Overall, this handbook identifies 10 elements of torque that can contribute to a quarter-turn valve’s working torque.
Example torque calculation summary graph
The first AWWA quarter-turn valve normal for 3-in. via 72-in. butterfly valves, C504, was printed in 1958 with 25, 50 and one hundred twenty five psi strain classes. In 1966 the 50 and 125 psi strain lessons have been increased to 75 and a hundred and fifty psi. The 250 psi stress class was added in 2000. The 78-in. and larger butterfly valve standard, C516, was first revealed in 2010 with 25, 50, 75 and 150 psi stress lessons with the 250 psi class added in 2014. The high-performance butterfly valve commonplace was revealed in 2018 and includes 275 and 500 psi strain classes as well as pushing the fluid flow velocities above class B (16 feet per second) to class C (24 feet per second) and class D (35 toes per second).
The first AWWA quarter-turn ball valve normal, C507, for 6-in. through 48-in. ball valves in a hundred and fifty, 250 and 300 psi stress courses was printed in 1973. In 2011, measurement range was elevated to 6-in. through 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 normal for resilient-seated cast-iron eccentric plug valves in 1991, the first a AWWA quarter-turn valve standard, C517, was not published until 2005. The 2005 dimension range was 3 in. by way of 72 in. with a a hundred seventy five
Example butterfly valve differential strain (top) and move price management home windows (bottom)
strain 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 increased the valve sizes or pressure lessons. The addition of the A velocity designation (8 fps) was added within the 2017 edition. This valve is primarily utilized in wastewater service the place pressures and fluid velocities are maintained at lower 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 through 1,500 mm), C522, is beneath improvement. This standard will embody the identical 150, 250 and 300 psi pressure courses and the identical fluid velocity designation of “D” (maximum 35 ft per second) as the present C507 ball valve standard.
In common, all of the valve sizes, flow rates and pressures have elevated because the AWWA standard’s inception.
AWWA Manual M49 identifies 10 parts that affect working torque for quarter-turn valves. These parts fall into two common classes: (1) passive or friction-based parts, and (2) energetic or dynamically generated components. Because valve manufacturers cannot know the precise piping system parameters when publishing torque values, revealed torques are typically limited to the 5 components of passive or friction-based components. These embody:
Passive torque components:
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 circulate velocity. The parts that make up energetic torque include:
Active torque parts:
Disc weight and middle of gravity torque
Disc buoyancy torque
Eccentricity torque
Fluid dynamic torque
Hydrostatic unbalance torque
When considering all these varied active torque parts, it’s possible for the actual working torque to exceed the valve manufacturer’s published torque values.
Although quarter-turn valves have been used within the waterworks trade for a century, they are being exposed to larger service strain and circulate fee service situations. Since the quarter-turn valve’s closure member is all the time situated within the flowing fluid, these larger service situations directly influence the valve. Operation of those valves require an actuator to rotate and/or hold the closure member within the valve’s physique because it reacts to all of the fluid pressures and fluid flow dynamic situations.
In addition to the elevated service conditions, the valve sizes are also rising. The dynamic situations of the flowing fluid have greater effect on the bigger valve sizes. Therefore, the fluid dynamic results turn into extra essential than static differential stress and friction hundreds. Valves can be leak and hydrostatically shell examined throughout fabrication. However, the full fluid move conditions can’t be replicated before web site set up.
Because of the trend for increased valve sizes and increased operating circumstances, it’s more and more necessary for the system designer, operator and owner of quarter-turn valves to raised understand the influence of system and fluid dynamics have on valve selection, building and use.
The AWWA Manual of Standard Practice M 49 is dedicated to the understanding of quarter-turn valves including working torque necessities, differential pressure, flow circumstances, throttling, cavitation and system installation differences that instantly influence the operation and profitable use of quarter-turn valves in waterworks methods.
The fourth version of M49 is being developed to incorporate the adjustments within the quarter-turn valve product requirements and installed system interactions. A new chapter might be dedicated to methods of control valve sizing for fluid move, stress control and throttling in waterworks service. This methodology consists of explanations on using strain, flow fee and cavitation graphical home windows to offer the person a radical image of valve performance over a variety of anticipated system operating situations.
Read: New Technologies Solve Severe Cavitation Problems
About the Authors
Steve Dalton began his profession 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 labored at Val-Matic as Director of Engineering. He has participated in standards creating organizations, together with AWWA, MSS, ASSE and API. Dalton holds BS and MS degrees 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 active member of each 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 worked with the Electric Power Research Institute (EPRI) in the growth of their quarter-turn valve efficiency prediction methods for the nuclear power business.

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