Outside screw stem rising gate valve 

The outside screw stem rising gate valve is also known as the lifting stem gate valve, which moves up and down with the gate plate during opening and closing.

When the gate valve is opened, you can see that the valve stem gradually rises, and the opening degree of the gate valve can be judged by the rise of the valve stem, and the valve can be judged by the position of the valve stem, whether the valve is in an open state or a closed state.

When the gate valve is opened, the valve stem should rise to the same height as the diameter of the gate valve, which is good for a spacious place, and is not suitable for a small place.
Common ones are BS5163 Resilient Seat Seal Rising Stem Gate Valve，API600 OSY Cast Steel Gate Valve

Non rising stem valve

Non rising stem valve is also known as rotary stem gate valve, the valve stem is rotating during the opening and closing process.

The handwheel drives the valve stem to rotate, and the valve stem drives the gate to move up and down to complete the switching process. There is also a guide groove between the gate and the valve body. Limit and guide the ram. The ram is fitted with internal thread and stem thread.

When the gate valve is opened, the valve stem only rotates and does not move up and down. The switching state of the gate valve cannot be seen from the outside, because there is no change in the appearance during the switching process, unlike the open-stem gate valve, which can see the rise and fall of the valve stem. Therefore, in important occasions, the valve stem indicator will be installed on its appearance, and the valve switching state can be distinguished.

Non rising stem gate valves are suitable for applications where space is limited because their height does not change when opened. The medium in the pipeline should be clean, and impurities will cause the valve stem and ram thread to get stuck, resulting in switch failure. The valve stem and gate thread are subjected to the erosion and corrosion of the medium, and the service life is not as long as the open stem gate valve.

Common ones are BS5163 Resilient Seat Seal Non-Rising Stem Gate Valve