Manual gate valve
A gate valve is a valve whose gate closing part moves in the vertical direction along the center line of the passage. It is generally composed of a valve body, a valve seat, a valve stem, a gate, a valve bonnet, and a sealing ring. It can be transformed into a variety of electric gate valves and pneumatic gate valves by equipping the transmission device and the gate valve. It can only be used for full opening and full closing in the pipeline, and cannot be used for adjustment and throttling.
Working principle
The gate of the gate valve moves linearly with the valve stem. Usually there is a trapezoidal thread on the lifting stem. Through the nut at the top of the valve and the guide groove on the valve body, the rotary motion is converted into linear motion, that is, the operating torque is converted into operating thrust.
Closed
The sealing surface can be sealed only by the medium pressure, that is, the sealing surface of the gate is pressed against the valve seat on the other side by the medium pressure to ensure the sealing of the sealing surface. This is self-sealing. Most gate valves use forced sealing, that is, when the valve is closed, the gate is forced to press against the valve seat by external force to ensure the sealing of the sealing surface.
Open
When the gate lift height is equal to 1:1 times the valve diameter, the fluid passage is completely unblocked, but this position cannot be monitored during operation. In actual use, the top of the valve stem is used as a mark, that is, the position where it cannot be opened, as its fully open position. In order to consider the locking phenomenon caused by temperature changes, it is usually opened to the top position and then reversed 1/2-1 turn as the fully open valve position. Therefore, the fully open position of the valve is determined by the position of the gate (i.e. the stroke).
Principle of Gate Valve
As the name implies, electric gate valves use electric actuators to control gate valves. They are mainly divided into upper and lower parts. The upper part is the electric actuator and the lower part is the gate valve. The actuator and the gate valve are connected, and the electric actuator controls the gate valve to open and close to achieve the on-off of the pipeline medium. Gate valves are generally suitable for on-off occasions and are normally open and closed valves. If the working conditions require adjustment, electric control valves, electric ball valves, electric butterfly valves, electric globe valves, etc. are generally used.
Debugging Methods
After connecting the valve, connect the external wires according to the external wiring diagram. Pay special attention to whether the input signal is a current signal or a voltage signal. They cannot be mixed. The positive and negative signals cannot be connected incorrectly. Users can check and debug one by one according to the following methods. Adjust the mechanical limit of the electric actuator: The adjustment of the mechanical limit is to make the actuator work only within the mechanical upper and lower limit range to prevent the actuator from over-limiting and causing danger or damaging the valve. As shown in the figure, the lever and the upper and lower limit stops are respectively provided. In the zero position state, the lower limit stop should be close to or close to the lever from the bottom to prevent the actuator from over-limiting. If the deviation is large, the clamping nut can be loosened and the stop block can be moved to the corresponding position, and the corresponding nut can be tightened; in the full position state, the upper limit stop should be close to or close to the lever from the top to prevent the actuator from over-limiting. If the deviation is large, the clamping nut can be loosened and the stop block can be moved to the corresponding position, and the corresponding nut can be tightened. When the power is not connected, the debugging process can use the handwheel to manually open the actuator to the zero position and full position of the required valve, and then make corresponding adjustments. The actuator can also be adjusted to the electric manual state when the power is on, and the actuator can be opened to the required zero position and full position by the up or down keys on the display. If the actuator does not move when the up or down key is pressed during the starting process, it is because of the limit switch limitation.
Applications
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