The opening and closing part of the gate valve is the gate. The movement direction of the gate is perpendicular to the direction of the fluid. The gate valve can only be fully opened and closed, and can not be adjusted and throttled. The gate has two sealing surfaces. The gate plate of the gate valve moves in a straight line with the stem, which is called the Rising stem gate valve. When opening the valve, once the gate lifting height is equal to 1:1 times the valve diameter, the flow passage is completely open, this position can’t be monitored when the valve running. In practical use, the vertex of the valve stem is used as the sign, that is, the position of the valve stem that is not moving is used as its full open position. In order to consider the locking phenomenon of temperature change, the valve is usually opened to the vertex position and reversed to 1/2-1 turn as the position of the fully open valve. Therefore, the full open position of the valve is determined by the position of the gate, that is, the stroke. Some gate valves, stem nuts set on the gate plate, hand wheel rotation to drive the rotation of the stem, and make the gate lift, this valve is called non-rising stem gate valve.
10. Packing gland