A Gate valve is often a linear motion on-off or shut-off valve. The gate-valve covers a disc or wedge having two seating surfaces that can come in contact while using valve seats to make a seal for stopping the flow check here. The pressure differential involving the upstream flow direction and downstream side of wedge causes the wedge or disc to make against the downstream seat creating more effective sealing around the downstream side from the wedge. Gate valve sits dormant to regulate flow as erosion of disc and seat might cause leakage. A gate valve in partially open or closed position is usually susceptible to vibration.
The shut-off part on the gate valve is created in the form of an wedge, that is flexible, with multiple plates or rigid.
Let us look at each from the subcategories:
Rigid wedge
To ensure a higher hermiticity of gate valves, it is strongly recommended to choose a stiff wedge. In this case, you should pay attention on the accuracy of wedge processing, that permits to coordinate the seat angle while using wedge angle without obstacles. In addition to that, rigid wedge application might cause dangerous events like gate jamming, or there might be problems using the opening of gate valves in case there is temperature fluctuations, corrosion build-up or sealing damages.
Wedge with 2 plates
The wedge includes several plates that are securely sure to each other and they are situated with an angle. Thanks to self-adjustment, the problem from the gate hermiticity from the closed position might be avoided.
Flexible wedge
Connected having an elastic part, the plates can clamp down and help the sealing tightness in closed position. The advantage of gate valves which has a flexible wedge for mounting within the pipeline is the fact there is no need of the complex adjustment on the valve body.
The sorts of rising-stem gate valve may be divided into wedge disc gate valve and parallel disc gate valve good sealing surface configuration. Wedge disc gate valve could be divided into: single disc type, double disc type and elastic disc type; parallel disc Type gate valve could be divided into single disc type and double disc type. According for the thread position with the valve stem, it is usually divided into rising-stem gate valve and non rising-stem gate valve.
When the rising-stem gate valve is closed, the sealing surface are only able to rely for the medium pressure to seal, that is certainly, only rely about the medium pressure to press the sealing surface in the disc towards the valve seat about the other side so that the sealing in the sealing surface, that's self-sealing. Most gate valves adopt forced sealing valve, that's, once the valve is closed, the disc have to be forced on the valve seat by external force to guarantee the tightness in the sealing surface.
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