Flat plate gate valve is a valve with a linear opening and closing action, which has a typical flat plate closing element perpendicular to the fluid, sliding and cutting into the fluid to close. As the gate of the flat plate gate valve closes, there is no wedge tightening force generated when the wedge gate closes, so relatively speaking, the operation is more flexible, longer service life, opening and closing force is smaller. Widely used in natural gas, light oil, chemical industry, urban construction, environmental protection and other industries, for cutting off the medium, and is suitable for sulfur-containing (H2S) heavy oil, sewage and venting and other systems, as well as fast flow rate, impurities, corrosion of the natural gas long-distance pipeline. Plate gate valve is a kind of sliding valve with parallel gate for closing member. The closing member can be a single gate or a double gate with an opening mechanism in the center. In the case of single-plate gate valves, the sealing pressure between the gate and the seat is generated by the medium pressure pushing the floating seat. For double gate flat plate gate valve, the spreading mechanism between the two gates can form a preload specific pressure to supplement the sealing specific pressure. Flat plate gate valves work well with clean fluids. If solid particles are entrained in the medium, this can increase wear on the sealing surfaces and cause leakage. The structure of the valve seat with spring load can adapt to the working conditions with significant temperature changes and possible deformation of the valve body.
The advantage of the flat gate valve is that when fully open, it is almost equivalent to a section of pipe of the same length, so the pressure loss of the medium through the valve is very small, and the flow coefficient (Cv value) of the valve is high.
Flat plate gate valve with guide hole installed in the pipeline can also be used directly to clear the pipe cleaner. Since the gate slides on both seat surfaces, the flat gate valve can also be used in pipelines with suspended particles. Opening and closing of the sealing surface of the flat plate gate valve is actually automatic positioning, the seat sealing surface is generally not subject to damage by the thermal deformation of the valve body, and even if the valve is closed in the cold state, after warming up its thermal elongation will not make the sealing surface subject to overload.
Flat plate gate valve without pilot hole, does not require a high degree of accuracy of the closing position of the gate, so the valve can be used to control the opening and closing position of the valve stroke. Flat plate gate valves will reach the maximum sealing force when the valve is closed, while the pressure loss of the valve will be close to the maximum, but the sealing area at the time of interaction is only a part of the total sealing area. When the gate moves roughly to 3/4 of the valve closing position, the medium is prone to tilt the gate to the seat hole, at this time, the seat hole and the outermost end of the gate will wear. In order to ensure that the sealing force and the permissible range of the amount of wear of the valve seat, so it is necessary to take into account, design a suitable seat width.