Flange gate valve

The flange gate valve is a gate valve with a flange connection. This type of connection is the most common. Flange gate valves are stable and reliable when used in pipelines, so flange gate valves are often used in high pressure pipelines.

The type of gate valve can be divided into wedge type gate valve and parallel gate type gate valve and wedge type gate type according to the sealing surface configuration. This type of valve should generally be installed horizontally in the pipeline.

When the gate valve is closed, the sealing surface can be sealed only by the medium pressure, that is, the sealing surface of the gate is pressed against the valve seat on the other side by the medium pressure to ensure the sealing of the sealing surface, which is self-sealing. Most of the gate valves are forced to seal, that is, when the valve is closed, the external force is forced to press the gate to the valve seat to ensure the sealing of the sealing surface.

The gate of the gate valve moves linearly with the valve stem, called the lift gate valve (also called the open gate valve). Usually, trapezoidal threads are provided on the lifting rod, and the rotary motion is changed into a linear motion by the nut at the top end of the valve and the guide groove on the valve body, that is, the operating torque is changed to the operating thrust.

When the valve is opened, when the lifting height of the shutter is equal to 1:1 times the diameter of the valve, the passage of the fluid is completely unblocked, but this position cannot be monitored during operation. In actual use, the apex of the valve stem is used as a mark, that is, the position where the valve is opened, as its fully open position. In order to consider the temperature change, the lock phenomenon is usually turned on to the apex position, and then back to 1/2-1 circle as the position of the fully open valve. Therefore, the fully open position of the valve is determined by the position of the gate (ie stroke).

Some gate valves and stem nuts are arranged on the gate plate, and the rotation of the hand wheel drives the valve stem to rotate, and the shutter is lifted. This valve is called a rotary lever gate valve or a dark rod gate valve.