non-rising stem gate valve
The valve stem nut is in the valve body and is in direct contact with the medium, and the gate is opened and closed by rotating the valve stem.
The advantages of the concealed rod structure are: when the valve is opened and closed, the overall height remains unchanged, and the installation space occupied is small, which is more suitable for environments with large diameters or limited installation space. If necessary, the dark rod structure can be equipped with an opening and closing indicator to indicate the degree of opening and closing.
The disadvantage of the concealed stem structure is that the valve stem thread is not only unable to be lubricated, but also directly eroded by the medium and easily damaged.
Rising stem gate valve
The valve stem nut is on the valve cover or bracket. When the valve is opened and closed, the valve stem is lifted and lowered by rotating the valve stem nut, thereby opening and closing the gate valve. The open stem structure is beneficial to the lubrication of the valve stem, and the degree of opening and closing is obvious, so it is widely used. However, because the stem of the rising stem gate valve is exposed and occupies a large space, it is not suitable for indoor use.
The difference between Non-rising stem gate valve and rising stem gate valve is:
1. The valve stem of the Non-rising stem gate valve rotates with the handwheel and will not move up and down. Only a rod is exposed, and its nut is fixed on the gate, and the gate is lifted by the rotation of the screw. The lifting screw (also called valve stem) of the rising stem gate valve is exposed, and the nut is close to the handwheel and is fixed (not rotating or moving axially). The gate is lifted by rotating the screw, and the screw and the gate are only opposite. Rotational movement without relative axial displacement. To put it simply, the 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.
2. The lead screw of the gate valve with dark stem cannot be seen, while the lead screw of the gate valve with open stem is exposed and can be seen.
