What are the structural differences between parallel gate valve and wedge gate valve
First of all, what is the parallel gate: that is, the sealing surface is parallel to the vertical center line, so the sealing surface of the valve body and the gate is also parallel to each other. This kind of gate valve is commonly used as double gate plate. In order to make the sealing surface of the valve body and the gate tightly contact each other when it is closed, it is often used to clamp the double-sided thrust wedge between the two gate plates. In this way, when the valve is closed, the double-sided thrust block contacts with the bottom of the valve body, and the double ram is pushed open to make the sealing surface of the gate and the valve body seal closely. This kind of double gate parallel gate is mostly used in low pressure pipeline such as small pipeline. Parallel gate valve uses single gate valve, but it is rare.
Wedge gate valve: that is, the sealing surface is at a certain angle with the vertical center line, and the higher the temperature of the medium is required, the greater the inclination angle is, so as to reduce the possibility of wedging the gate when the temperature changes.
Wedge gate valve has both single and double gate valves. The advantage of double gate plate is sealing, but the accuracy of angle is low, the ram is not easily wedged by temperature change, and the wear of sealing surface can be compensated by adding gasket.
The disadvantage is that the structure is complex, easy to stick in the dry medium, more importantly, the upper and lower baffles are easy to fall off after long-term corrosion. Although the single ram has some disadvantages such as high accuracy requirement of sealing angle, difficult processing and wedge of ram due to temperature change, it is simple in structure and reliable in use. Especially after being changed into elastic ram, it can produce slight elastic deformation to make up for the deviation in angle processing of sealing surface, so it is widely used at present.