Understanding Torque for Quarter-Turn Valves

Valve manufacturers publish torques for his or her merchandise in order that actuation and mounting hardware could be correctly chosen. However, printed torque values often represent solely the seating or unseating torque for a valve at its rated pressure. While these are important values for reference, revealed valve torques don’t account for actual installation and working characteristics. In order to determine the precise working torque for valves, it’s essential to know the parameters of the piping systems into which they are put in. Factors corresponding to installation orientation, direction of circulate and fluid velocity of the media all impact the precise operating torque of valves.
Trunnion mounted ball valve operated by a single performing spring return actuator. Photo credit: Val-Matic
The American Water Works Association (AWWA) publishes detailed info on calculating working torques for quarter-turn valves. This info seems in AWWA Manual M49 Quarter-Turn Valves: Head Loss, Torque, and Cavitation Analysis. Originally published in nuova fima pressure gauge ราคา with torque calculations for butterfly valves, AWWA M49 is at present in its third version. In addition to information on butterfly valves, the current version also contains working torque calculations for other quarter-turn valves together with plug valves and ball valves. Overall, this guide identifies 10 elements of torque that may contribute to a quarter-turn valve’s operating torque.
Example torque calculation summary graph
AWWA QUARTER-TURN VALVE HISTORY
The first AWWA quarter-turn valve commonplace for 3-in. by way of 72-in. butterfly valves, C504, was revealed in 1958 with 25, 50 and 125 psi strain courses. In 1966 the 50 and 125 psi stress lessons had been increased to seventy five and a hundred and fifty psi. The 250 psi pressure class was added in 2000. The 78-in. and larger butterfly valve commonplace, C516, was first revealed in 2010 with 25, 50, 75 and 150 psi pressure classes with the 250 psi class added in 2014. The high-performance butterfly valve standard was revealed in 2018 and contains 275 and 500 psi pressure classes in addition to pushing the fluid move velocities above class B (16 feet per second) to class C (24 ft per second) and class D (35 feet 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 pressure classes was revealed in 1973. In 2011, dimension vary was increased to 6-in. through 60-in. pressure gauge weksler ราคา have all the time 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 normal for resilient-seated cast-iron eccentric plug valves in 1991, the primary a AWWA quarter-turn valve commonplace, C517, was not published until 2005. The 2005 measurement vary was 3 in. by way of seventy two in. with a a hundred seventy five
Example butterfly valve differential strain (top) and move fee control windows (bottom)
pressure class for 3-in. via 12-in. sizes and a hundred and fifty psi for the 14-in. via 72-in. The later editions (2009 and 2016) haven’t increased the valve sizes or pressure classes. The addition of the A velocity designation (8 fps) was added within the 2017 version. 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 via 1,500 mm), C522, is underneath improvement. This commonplace will embody the identical one hundred fifty, 250 and 300 psi pressure courses and the same fluid velocity designation of “D” (maximum 35 ft per second) as the current C507 ball valve standard.
In common, all the valve sizes, flow rates and pressures have elevated since the AWWA standard’s inception.
COMPONENTS OF OPERATING TORQUE
AWWA Manual M49 identifies 10 elements that have an result on operating torque for quarter-turn valves. These elements fall into two basic categories: (1) passive or friction-based elements, and (2) energetic or dynamically generated parts. Because valve producers cannot know the actual piping system parameters when publishing torque values, published torques are generally limited to the five elements 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 components are impacted by system parameters such as valve orientation, media and flow velocity. The components that make up active torque embrace:
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 is potential for the actual operating torque to exceed the valve manufacturer’s printed torque values.
WHY IS M49 MORE IMPORTANT TODAY?
Although quarter-turn valves have been used within the waterworks trade for a century, they’re being uncovered to greater service pressure and flow fee service conditions. Since the quarter-turn valve’s closure member is all the time positioned within the flowing fluid, these greater service conditions instantly impact the valve. Operation of these valves require an actuator to rotate and/or maintain the closure member within the valve’s body because it reacts to all the fluid pressures and fluid flow dynamic circumstances.
In addition to the elevated service situations, the valve sizes are also increasing. The dynamic circumstances of the flowing fluid have higher effect on the larger valve sizes. Therefore, the fluid dynamic effects turn out to be extra necessary than static differential stress and friction loads. Valves may be leak and hydrostatically shell tested throughout fabrication. However, the complete fluid circulate situations can’t be replicated before website set up.
Because of the trend for elevated valve sizes and increased working situations, it’s increasingly necessary for the system designer, operator and owner of quarter-turn valves to better perceive the influence of system and fluid dynamics have on valve choice, construction and use.
The AWWA Manual of Standard Practice M 49 is devoted to the understanding of quarter-turn valves together with working torque necessities, differential pressure, flow circumstances, throttling, cavitation and system set up differences that instantly influence the operation and profitable use of quarter-turn valves in waterworks systems.
AWWA MANUAL OF STANDARD PRACTICE M49 4TH EDITION DEVELOPMENTS
The fourth edition of M49 is being developed to include the modifications in the quarter-turn valve product requirements and installed system interactions. A new chapter shall be dedicated to strategies of control valve sizing for fluid move, stress control and throttling in waterworks service. This methodology includes explanations on the use of stress, flow rate and cavitation graphical home windows to supply the user a radical image of valve performance over a range of anticipated system working circumstances.
Read: New Technologies Solve Severe Cavitation Problems
About the Authors
Steve Dalton began his profession as a consulting engineer in the waterworks trade 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 developing 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 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 also labored with the Electric Power Research Institute (EPRI) in the growth of their quarter-turn valve efficiency prediction methods for the nuclear energy trade.
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