Fluid control refers to the use of various fluid control components (various pumps, valves, cylinders) and hydraulic system accessories (filters, pipe joints, liquid level gauges, pressure instruments, etc.) to form a closed loop for automatic control. 

The basic principle of fluid control is to use the dynamic characteristics of fluid to make the fluid move along a predetermined path and speed by designing and controlling the shape, size, position and control method of flow channels, valves, pumps and other components.