Gate valve is basically used in fluid pipelines for controlling the flow of fluid. There will be one gate or wedge in gate valve and it will control the fluid flow. Shape of gate or wedge of gate valve will be a type of flat circular plate or rectangular plate. Sometimes, gate or wedge is also termed as disc of gate valve.
valve which is used to open and close the gate valve. When handle wheel will be rotated, it will move the gate or wedge in upward or downward direction across the line of fluid flow.
When handle wheel will be rotated in clockwise direction, steam and gate will move in downward direction across the fluid flow line and gate will be tightly located between the two seats. Hence there will not be any leakage of fluid through the valve once valve is closed completely.
When handle wheel will be rotated in anti-clockwise direction, steam and gate will move in upward direction across the fluid flow line and valve will be opened from closed position and will permit the flow of fluid through the gate valve. Once gate valve is completely opened, it will permit no resistance or very little resistance to the flow of fluid.
We can use gate valve in semi-open condition also but there will be one issue of erosion of gate as fluid will strike the gate if valve is partially open. Therefore gate valve should be used in completely closed or completely open condition.