Globe valve operating torque analysis
Globe valves in full open position by the stage, with began to close down, the disc in the disc and fluid pressure difference, causes to prevent disc decline, and the resistance force rapid increases with the disc decreases. When the globe valves are fully closed, disc front and back differential pressure is equal to medium work pressure, this is the largest resistance force. Then forced to seal globe valve, closed instantaneous operating force increases quickly. In the process of valve, due to the medium pressure or disc and differential pressure of thrust is helping open valve. It should be noted that in open valve moments of torque may exceed the torque when the valve is closed because of the static friction force to overcome.
Globe valve opens, disc height reach cut-off valve opens the nominal diameter 25% ~ 30%, which has reached the maximum flow, namely that globe valves open position, so has reached the globe valve in full open position should be determined by the valve stroke. Globe valves are closed and locked again after open and forced the gate seal globe valves, therefore, similar to the closed position should be increased to specified by operating torque.
