Gate valves can be divided into:
1. Rising stem gate valve: The valve stem nut is placed on the valve cover or bracket. When opening and closing the gate, the valve stem nut is rotated to achieve the lifting and lowering of the valve stem. This structure is beneficial for the lubrication of the valve stem and has a significant degree of opening and closing, therefore it is widely adopted.
2. Non rising stem gate valve: The stem nut is located inside the valve body and in direct contact with the medium. When opening and closing the gate, it is achieved by rotating the valve stem. The advantage of this structure is that the height of the gate valve remains constant, so the installation space is small, suitable for large diameter or limited installation space gate valves. This structure should be equipped with an opening and closing indicator to indicate the degree of opening and closing. The disadvantage of this structure is that the valve stem thread not only cannot be lubricated, but also directly accepts medium erosion and is prone to damage.
The main differences between rising stem gate valves and non rising stem gate valves are:
1. The lifting screw of the non rising flange gate valve only rotates without moving up and down, and only one rod is exposed. Its nut is fixed on the gate plate, and the gate plate is lifted by the rotation of the screw, without a visible gate frame; The lifting screw of the rising stem flange gate valve is exposed, and the nut is tightly attached to the handwheel and fixed (not rotating or axially moving). The gate is lifted by rotating the screw. The screw and gate only have relative rotational motion without relative axial displacement, and the appearance is a door-shaped bracket.
2. The lead screw cannot be seen in the concealed valve, while the lead screw can be seen in the exposed valve.

3. When a non rising valve is opened or closed, the steering wheel and valve stem are connected together and relatively stationary. It is achieved by rotating the valve stem at a fixed point to drive the valve disc up and down to complete the opening and closing. Rising stem valves raise or lower the valve disc through a threaded transmission between the valve stem and steering wheel. Simply put, a rising stem valve is a valve disc that moves up and down together with the valve stem, and the steering wheel is always at a fixed point.