In the production process, in order to make the medium pressure, flow and other parameters in line with the requirements of the process flow, need to install the regulator to adjust the above parameters. The main working principle of the regulating mechanism is to change the flow area between the valve disc and the valve seat to achieve the purpose of adjusting the above parameters. Belong to this type of valve are referred to as control valves, which are divided into relying on power driven media itself is called self driven control valve such as valve, regulator valve, all of the leading driving force of the (such as electricity, compressed air and fluid power) known for his drive control valve, such as electric control valve, pneumatic control valve and hydraulic control valve etc..
