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Analysis Of Operating Torque Of Gate Valve

Ningbo Fenfa Valve Co.,Ltd | Updated: Jul 19, 2017

  Analysis of Operating Torque of Gate Valve

  When the gate valve opening at 10% or more, the gate valve axial force, that is, the valve operating torque changes little. When the gate valve opening less than 10%, due to fluid throttling, so that the valve before and after the pressure increase. This pressure on the role of the valve, so that the stem needs a larger axial force to drive the gate, so in this range, the gate valve operating torque changes are relatively large. Elastic gate of the gate valve, close to the required operating torque than the rigid gate to be larger.

  When the shutter is closed, the sealing surface of the sealing method is different, will produce a different situation. For the automatic sealing gate valve (including the plate gate valve), when the valve is closed, the gate seal surface just right seat sealing surface, that is, the gate valve fully open position. But this position in the gate valve operating conditions can not be monitored, so in actual use, is the gate valve to the end of the position as the gate valve fully closed position. It can be seen that the fully sealed gate valve is fully closed by the position of the gate (ie stroke) to determine. For forcedly sealed gate valves, the pressure must be applied to the valve seat when closed. This pressure can ensure that the seal between the gate and the valve seat is strictly sealed, is forced sealing valve sealing force. This sealing force will continue to be used due to the self-locking of the stem nut. Obviously, in order to provide the sealing force to the gate, the stem nut to pass the torque than the valve during the operation of the torque. It can be seen, for the mandatory seal of the gate valve, fully closed position is the stem nut by the size of the torque to determine.

  After the gate valve is closed, the thermal expansion of the gate valve component will increase the pressure between the gate and the valve seat due to the change of the medium or the ambient temperature, which is reflected on the stem nut, which makes it difficult to open the gate valve again. Therefore, the torque required to open the gate valve is greater than the torque required to close the gate valve. In addition, the static friction coefficient between them is larger than the dynamic friction coefficient for a pair of contact surfaces that are in contact with each other, Movement, the need to exert a greater force to overcome the static friction; due to temperature changes, so that the pressure between the sealing surface becomes larger, need to overcome the static friction also will become larger, so that when the gate valve, Sometimes will increase a lot.

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