Gate valve is a shutter of the opening and closing member. The direction of movement of the gate is perpendicular to the direction of the fluid. The gate valve can only be fully open and fully closed, and cannot be adjusted and throttled. The gate valve is sealed by the contact between the valve seat and the gate. Usually, the sealing surface will weld the metal material to increase the wear resistance, such as surfacing 1Cr13, STL6, stainless steel, and etc. The gate has a rigid gate and an elastic gate. According to the gate, the gate valve is divided into a rigid gate valve and a resilient gate valve.
The gate valve is divided into two types: wedge type and parallel type according to the structure of the shutter.
Wedge rams are available in three configurations: single ram, double ram and resilient ram.
The gate valve is further divided into a slab gate valve and a knife gate valve according to the type of structure.
Classified by shell/body material, gate valves can be divided into:
Metal material valves: such as carbon steel valves, alloy steel valves, stainless steel valves, cast iron valves, titanium alloy valves, Monel valves, copper alloy valves, lead alloy valves, etc.
Metal valve body lining valves: such as rubber-lined valves, fluorine-lined valves, lead-lined valves, lined plastic valves, lining enamel valves.
Non-metallic valve: such as ceramic valves, glass valves, plastic valves.
Advantage
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 lifting 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, PTFE packing, reliable sealing, light and flexible operation.
Disadvantage
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.
