Torque Analysis Of Globe Valve

When the stop valve starts to close from the fully open position, as the valve disc descends, the fluid creates a pressure difference between the front and rear of the valve disc to prevent the valve disc from falling, and this resistance increases rapidly as the valve disc descends. When the stop valve is fully closed, the pressure difference between the front and back of the disc is equal to the working pressure of the medium, and the resistance is the largest at this time. Coupled with the mandatory sealing force, the operating force at the moment the globe valve is closed increases rapidly. During the opening process of the valve, the thrust caused by the medium pressure or the pressure difference between the front and rear of the disc all help to open the valve. It should be pointed out that the torque at the moment of opening the valve may exceed the torque at the moment of closing the valve, because at this time a large static friction force has to be overcome. When the stop valve is opened, when the opening height of the valve disc reaches 25% to 30% of the nominal diameter of the stop valve, the flow rate has reached the maximum, which means that the stop valve has reached the fully open position, so the fully open position of the stop valve should be controlled by the valve disc. to determine the itinerary. The situation when the stop valve is closed and opened again after being tightly closed is similar to that of the forced sealing gate valve. Therefore, the closing position of the stop valve should be determined by increasing the operating torque to the specified value.