£¨1£© Different energy sources are used Pneumatic components and devices can adopt the method of centralized gas supply from air compression stations, and adjust the working pressure of their respective pressure reducing valves according to different usage requirements and control points. Hydraulic valves are equipped with return oil pipelines to facilitate the collection of used hydraulic oil in the oil tank. Pneumatic control valves can directly discharge compressed air into the atmosphere through exhaust ports.

There are many ways to classify valves based on their different functions. Here are the following:. 1. Classify by function and purpose (1) Block valve: Block valve, also known as closed-circuit valve, is used to connect or block the medium in the pipeline. Block valves include gate valves, globe valves, plug valves, ball valves, butterfly valves, and diaphragms. (2) Check valve: Check valve, also known as one-way valve or check valve, is used to prevent the backflow of medium in the pipeline. The bottom valve of the water pump for suction closure also belongs to the category of check valves.