The difference between the parallel double gate valve and the wedge gate valve is that the sealing surface is parallel to the vertical centerline, so the sealing surface of the valve body and the gate are also parallel to each other. The most common type of this kind of gate valve is the double gate type. In order to make the valve body and the two sealing surfaces of the gate closely contact when closed, a double-sided thrust wedge is often used between the two gates. In this way, when the valve is closed, the double-sided thrust sub-block contacts the bottom of the valve body and gradually receives force, and the double gate is pushed open so that the sealing surface of the gate is sealed and tightly attached to the valve body. This type of double gate parallel gate is mostly used on low pressure pipelines such as small pipelines. Parallel double gate valve with single gate is also rare but rare.
The wedge gate valve has single and double gates. The advantage of the double gate type is that the accuracy of the sealing and the angle is lower, the temperature change is not easy to make the gate wedged, and the sealing surface wear can be compensated with gaskets.