1. Gate valve Gate valve is also called gate valve, is a widely used valve. Its closing principle is that the sealing surface of the gate and the sealing surface of the valve seat are highly smooth, smooth and consistent, fit with each other, can prevent the medium from flowing, and rely on the top mold, spring or the mold shape of the gate to enhance the sealing effect. It mainly cuts off in the pipeline. Its advantages are small fluid resistance, easy opening and closing, can be used in the case of two-way flow of the medium, no directionality, sealing surface is not easy to be eroded when fully opened, short structure length, not only suitable for small valves, but also suitable for making Big valve. Gate valves are divided into two types according to the thread of the valve stem, one is the exposed stem type, and the other is the concealed stem type. According to the structure of the gate, there are two types, one is parallel, and the other is mode.
2. Shut-off valve, is also called cut-off gate, is the most widely used valve, its popularity, is due to the small friction between the sealing surfaces during the opening and closing process, is more durable, the opening height is not large, It is easy to manufacture and convenient to maintain. It is not only suitable for medium and low pressure, but also suitable for high pressure. Its closing principle is to rely on the pressure of the valve stem to make the disc sealing surface and the valve seat sealing surface closely fit, and to prevent the medium from flowing. The shut-off valve only allows the medium to flow in one direction, and is directional when installed. Its structural length is longer than that of the gate valve. At the same time, the fluid resistance is large, and the sealing reliability is not strong during long-term operation.