Calculation of valve (butterfly valve) torque!
Thread Content
Are there any people working in valve technology? Come and discuss the issue of torque! Take the butterfly valve as an example! Calculate a value using the formula in the valve manual, and then add a safety factor! I usually calculate it this way! But I always feel that it’s difficult to ensure the accuracy of the torque values obtained in this way! First, the data required for calculation is difficult to obtain comprehensively and accurately! Second is the complexity of the operating conditions, which makes it difficult to fully simulate using mathematical formulas! I’ve listened to Teacher Lu’s lectures; he said that accurate torque values are obtained through measurement!
Butterfly valve specifications: Standard valve disc for butterfly valves; maximum pressure difference: DN 6bar, 10bar, 200 LBF/IN2; 13bar, 285 LBF/IN2; 25bar, 50, 14, 14, 15, 15, 15, 15; 65, 14, 14, 17, 17, 20, 20; 80, 19, 19, 22, 22; 40, 40; 100, 33, 33, 34, 34; 50, 50; 125, 46, 46, 48, 48; 70, 70; 150, 72, 72, 73, 73; 95, 95; 200, 245; 145, 155, 155; 220, 220; 250, 230, 230, 236, 236; 320, 320; 300, 320, 320; 330, 330; 421, 421; 350, 560, 570, 720, 790; 400, 770, 850, 1000, 1180; 450, 1210, 1220, 1380, 1520; 500, 1420, 1430, 1780, 1930; 600, 2820, 2830, 3530, 3670; 700, 4860, 4970; 750, 5230, 5280; 800, 6500, 6600; 900, 7620, 8010; 1000, 8540, 10810; 1100, 9760; 15110; 1200, 13700; 21200
Bro, how do I view what you sent? ?
Well... I do have information on this topic! I mean, are these data calculated or measured? If calculating, what are the things to keep in mind? If measuring, what methods and equipment should be used?
I work in the field of butterfly valves, so I pay close attention to their torque. The torque of a valve can only be determined through calculations combined with ongoing testing of the actual valve. 1. The torque calculated theoretically is closely related to the precision of actual production and process control; therefore, theoretical values, especially those listed in calculation sheets, can only serve as a reference. 2. For new valves of a given diameter, we continuously test their torque. For example, if we have 50 sets of DN250 valves ordered, and all of them are to be equipped with electric drives, then we measure the torque under full pressure differences, and compare the actual torque values with the theoretical ones to ensure accuracy. 3. If the actual torque of the valve is much higher than the theoretical value, we need to determine whether there is an issue with the theoretical calculation formulas or with the manufacturing process. 4. Taking butterfly valves and ball valves as examples, since their valve stems are equipped with sleeves, the difference in torque can be significant depending on whether those sleeves are made of self-lubricating PTFE or metal stainless steel. It’s therefore difficult to say exactly how to calculate the most accurate torque value. It’s essential to work closely with the factory to verify the accuracy of the formulas and actual production processes. Otherwise, no matter how accurate the calculations may be, poor quality control by the factory can result in significantly higher torques, which would be a serious problem.
Are there any devices for measuring torque? A torque wrench?
Can I upload the calculation formulas for ventilation butterfly valves?
For a gate valve equipped with a multi-turn electric actuator and a gearbox, where the output torque of the electric actuator is 300 NM, how is this torque converted into the torque required for the gate valve?
The calculation of torque, just like the sealing pressure ratio, is based on estimated values. Different valve designs result in significant variations in torque values; angular-motion valves may yield more accurate calculations. For valves such as gate valves that can deform under pressure, it is necessary to take into account the deformation of the valve body under such pressure. No matter how you calculate it, it’s not accurate
Theoretical calculations will certainly differ from the actual values. Some calculation parameters, such as friction coefficients, and especially the compressing force at the packing area, are all estimates. To obtain accurate results, it is necessary to make adjustments based on the test data from the factory, such as by introducing correction factors, in order to improve the accuracy of the calculations