First, the gate valve
The valve opening is controlled by the up and down movement of the valve plate. The valve plate is like a gate. When the gate valve is closed, the sealing surface can be sealed only by the medium pressure, that is, the sealing surface of the shutter is pressed against the valve seat of the other side only 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 types of gate valves can be divided into wedge gate gate valves and parallel gate gate valves according to the sealing surface configuration. The wedge gate valve can be further divided into: single gate type, double gate type and elastic gate type; parallel gate type gate valves can be divided into single gate type and double gate type. According to the thread position of the valve stem, it can be divided into two types: open gate valve and dark gate valve. There are many manufacturers of gate valves in China, and the connection sizes are mostly not uniform. Performance characteristics
1. The flow resistance is small. The inner medium passage of the valve body is straight through, the medium flows in a straight line, and the flow resistance is small.
2. It is more labor-saving when opening and closing. Compared with the shut-off valve, the direction of movement of the ram is perpendicular to the direction of flow of the medium, whether it is open or closed.
3, high height, long opening and closing time. The opening and closing stroke of the shutter is large, and the drop is performed by the screw.
4. The water hammer phenomenon is not easy to produce. The reason is that the shutdown time is long.
5. The medium can flow in any direction on both sides, which is easy to install. The gate valve channels are symmetrical on both sides.
6. The length of the structure (the distance between the two connecting end faces of the casing) is small.
7. Simple shape, short structure length, good manufacturing process and wide application range.
8. Compact structure, good rigidity of the valve, smooth passage, small flow resistance, stainless steel and hard alloy on the sealing surface, long service life and PTFE packing. Sealed reliably. Light and flexible operation.
Erosion and abrasion are easily caused between the sealing surfaces, and maintenance is difficult. The external dimensions are large, and a certain space is required for opening, and the opening and closing time is long. The structure is more complicated.