What are the differences between rising stem gate valves and non-rising stem gate valves

According to the different movements of the valve stem during the opening and closing of the gate valve, gate valves are divided into two types: open stem type and concealed stem type.

Rising stem gate valve: The valve stem thread is exposed outside the valve body. When opening the valve, the valve stem extends out of the handwheel. Its advantages are that the opening size of the valve can be judged by the extension length of the valve stem, the contact length between the valve stem and the medium is relatively small, and the thread part is basically not affected by the corrosion of the medium. The disadvantage is that the extension space height is large.

Concealed stem gate valve: The valve stem thread fits with the internal thread on the gate plate inside the valve stem. When the valve is opened, the valve stem only rotates without moving up and down, and the gate plate rises along the valve stem thread. The advantage is that the outward extension space is small. The disadvantage is that the opening of the valve cannot be determined based on the condition of the valve stem, and the valve stem thread is prone to corrosion due to long-term contact with the medium.

Gate valves have the advantages of low fluid resistance, constant medium flow direction, slow opening without water hammer phenomenon, and easy flow regulation. However, their disadvantages include complex structure, large size, long opening and closing time, and difficult maintenance of the sealing surface. Because it is widely used in large-diameter water supply pipelines, it is also called a water gate.

Precautions for use

When the valve stem is fully opened or closed, no further force should be applied; otherwise, the internal threads or pin screws may be pulled apart, causing damage to the valve.

2. When the valve cannot be opened or closed directly by hand, an F-wrench can be used for opening or closing.

3. When opening or closing the valve, pay attention to observing the sealing surface of the valve, especially the packing gland, to prevent leakage.