Gate Valve Installation and Maintenance Precautions

The handwheel, handle and transmission mechanism are not allowed to be used for lifting, and collision is strictly prohibited. Double-gate gate valves should be installed vertically (i.e. the stem is in the vertical position and the handwheel is on top). The gate valve with the bypass valve should open the bypass valve before opening (to balance the pressure difference between the inlet and the outlet and reduce the opening force). The gate valve with transmission mechanism shall be installed according to the provisions of the product instruction manual. If the valve is used frequently, lubricate it at least once a month. The gate valve is used as a cut-off medium. When fully open, the entire flow is straight, and the pressure loss of the medium is minimal at this time. Gate valves are usually suitable for conditions that do not require frequent opening and closing, and keep the gate fully open or fully closed.

1. The gate valve is not suitable for use as regulation or throttling

For high-speed flowing media, the gate can cause vibration of the gate when it is partially opened, and the vibration may damage the sealing surface of the gate and the valve seat, and the throttling will cause the gate to be eroded by the medium. From the structural form, the main difference is the form of the sealing element used. According to the form of the sealing element, the gate valve is often divided into several globe valves types, such as: wedge gate valve, parallel gate valve, parallel double gate valve, wedge double gate gate valve, etc. The most common forms are the wedge gate valve and the parallel gate valve.

2. Matters needing attention when using the gate valve disc

The function of this type of valve is to allow the medium to flow in only one direction, and to prevent flow in one direction. Usually this kind of valve works automatically. Under the action of fluid pressure flowing in one direction, the valve flap opens; when the fluid flows in the opposite direction, the fluid pressure and the self-coincident valve flap of the valve flap act on the valve seat, thereby cutting off the flow. Among them, the check valve belongs to this type of valve, which includes swing check valve and lift check valve. Swing check valves have a hinge mechanism and a door-like disc that rests freely against the sloping seat surface. In order to ensure that the valve disc can reach the proper position of the valve seat surface every time, the valve disc is designed in the hinge mechanism, so that the valve disc has enough swing space and makes the valve disc truly and comprehensively contact the valve seat. Discs can be made entirely of metal, or inlaid with leather, rubber, or synthetic overlays, depending on the performance requirements.

According to the conditions of use, the disc can be of all-metal structure, or it can be in the form of a rubber pad or rubber ring embedded on the disc holder. Like the globe valve, the passage of fluid through the lift check valve is also narrow, so the pressure drop through the lift check valve is larger than that of the swing check valve, and the flow of the swing check valve is limited rare.

In the production process, in order to make the pressure, flow and other parameters of the medium meet the requirements of the technological process, it is necessary to install an adjustment mechanism to adjust the above parameters. The main working principle of the adjustment mechanism is to achieve the purpose of adjusting the above parameters by changing the flow area between the valve disc and the valve seat. These valves are collectively referred to as control valves, which are divided into self-propelled control valves that rely on the power of the medium itself, such as pressure reducing valves, pressure-stabilizing valves, etc.) is called other-driven control valve, such as electric control valve, pneumatic control valve and hydraulic control valve, etc.