A control valve, also known as a control valve, accepts the control signal output from the regulating control unit and operates to change the fluid flow with the help of power. Control valves are generally composed of actuators and valves. Control valves are suitable for air, water, steam, various corrosive media, slurry, oil and other media, widely used in electric power, chemical industry, metallurgy, environmental protection, water treatment, light industry, building materials and other industrial automation system fields.

Control valves can be divided into pneumatic control valves, electric control valves, hydraulic control valves three kinds, namely, pneumatic control valves with compressed air as the power source, electric control valves with electricity as the power source, electric-hydraulic control valves powered by liquid media (such as oil, etc.) pressure, in addition, according to its function and characteristics, there are hydraulic control valves, solenoid valves, electronic, intelligent, fieldbus-type control valves, and so on.

 Straight-through single-seat valve, the valve body has only 1 seat and sealing surface, simple structure, good sealing effect, is a commonly used valves. Straight-through double seat valve. Valve body has two seats and sealing surface, large flow capacity, unbalanced force is small, but the leakage is large, cut off the effect is poor. Sleeve valve spool inside the valve body guided by the sleeve, the sleeve is opened on the window for determining the flow and flow characteristics, the spool can be opened on the balance hole to reduce the unbalance force, sleeve valve adjustable ratio, vibration, unbalance force is small, good interchangeability, can be applied to most of the single and double-seat valves for the application of the occasions, is not applicable to the particles and the dirtier media. The shape of the sleeve has three kinds: quick-open, linear and equal percentage.