Valve producers publish torques for their products so that actuation and mounting hardware may be correctly chosen. However, printed torque values usually represent solely the seating or unseating torque for a valve at its rated stress. While these are essential values for reference, revealed valve torques do not account for precise set up and working characteristics. In order to determine the precise working torque for valves, it’s needed to know the parameters of the piping methods into which they’re installed. Factors corresponding to installation orientation, direction of move and fluid velocity of the media all influence 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 operating torques for quarter-turn valves. This information seems 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 includes operating torque calculations for different quarter-turn valves together with plug valves and ball valves. เกจวัดแรงดันไฮดรอลิค , this manual identifies 10 elements of torque that can 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 commonplace for 3-in. through 72-in. butterfly valves, C504, was published in 1958 with 25, 50 and 125 psi strain classes. In 1966 the 50 and 125 psi stress lessons have been elevated to seventy five and a hundred and fifty psi. The 250 psi strain class was added in 2000. The 78-in. and bigger butterfly valve normal, C516, was first printed in 2010 with 25, 50, 75 and one hundred fifty psi stress classes with the 250 psi class added in 2014. The high-performance butterfly valve commonplace was revealed in 2018 and consists of 275 and 500 psi pressure classes in addition to pushing the fluid flow velocities above class B (16 ft per second) to class C (24 ft per second) and sophistication D (35 toes per second).
The first AWWA quarter-turn ball valve standard, C507, for 6-in. through 48-in. ball valves in 150, 250 and 300 psi strain classes was revealed in 1973. In 2011, dimension range was elevated to 6-in. through 60-in. These valves have always 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 primary a AWWA quarter-turn valve standard, C517, was not revealed till 2005. The 2005 dimension range was three in. through 72 in. with a a hundred seventy five
Example butterfly valve differential strain (top) and circulate rate management windows (bottom)
stress 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) haven’t increased the valve sizes or stress courses. The addition of the A velocity designation (8 fps) was added in the 2017 edition. 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 recognized in 2018 and the AWWA Rotary Cone Valves, 6 Inch Through 60 Inch (150 mm by way of 1,500 mm), C522, is under improvement. This standard will encompass the identical one hundred fifty, 250 and 300 psi pressure lessons and the same fluid velocity designation of “D” (maximum 35 ft per second) as the present C507 ball valve standard.
In basic, all the valve sizes, flow rates and pressures have increased because the AWWA standard’s inception.
COMPONENTS OF OPERATING TORQUE
AWWA Manual M49 identifies 10 components that have an result on operating torque for quarter-turn valves. These parts fall into two basic classes: (1) passive or friction-based components, and (2) energetic or dynamically generated parts. Because valve producers can not know the precise piping system parameters when publishing torque values, printed torques are typically restricted to the five parts of passive or friction-based parts. These include:
Passive torque parts:
Seating friction torque
Packing friction torque
Hub seal friction torque
Bearing friction torque
Thrust bearing friction torque
The different 5 elements are impacted by system parameters similar to valve orientation, media and circulate velocity. The components that make up energetic torque embrace:
Active torque parts:
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 parts, it’s potential for the actual operating torque to exceed the valve manufacturer’s revealed torque values.
WHY IS M49 MORE IMPORTANT TODAY?
Although quarter-turn valves have been used in the waterworks trade for a century, they are being uncovered to greater service strain and flow price service conditions. Since the quarter-turn valve’s closure member is at all times situated within the flowing fluid, these larger service situations instantly impression the valve. Operation of these valves require an actuator to rotate and/or maintain the closure member throughout the valve’s body because it reacts to all the fluid pressures and fluid circulate dynamic conditions.
In addition to the increased service situations, the valve sizes are additionally increasing. The dynamic situations of the flowing fluid have higher effect on the bigger valve sizes. Therefore, the fluid dynamic effects become more necessary than static differential pressure and friction hundreds. Valves could be leak and hydrostatically shell examined throughout fabrication. However, the full fluid move situations can’t be replicated earlier than website set up.
Because of the pattern for elevated valve sizes and elevated operating conditions, it is more and more essential for the system designer, operator and proprietor of quarter-turn valves to higher understand the impact of system and fluid dynamics have on valve choice, building and use.
The AWWA Manual of Standard Practice M forty nine is dedicated to the understanding of quarter-turn valves together with working torque requirements, differential stress, flow conditions, throttling, cavitation and system installation variations that instantly affect the operation and successful use of quarter-turn valves in waterworks systems.
AWWA MANUAL OF STANDARD PRACTICE M49 4TH EDITION DEVELOPMENTS
The fourth version of M49 is being developed to incorporate the adjustments in the quarter-turn valve product requirements and installed system interactions. A new chapter shall be dedicated to methods of control valve sizing for fluid flow, pressure management and throttling in waterworks service. This methodology includes explanations on the use of pressure, flow price and cavitation graphical home windows to offer the consumer a thorough picture of valve performance over a spread of anticipated system working 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 standards 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 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) within the growth of their quarter-turn valve performance prediction methods for the nuclear energy industry.
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