The electric control valve is an important execution unit instrument in the process of industrial automation process control. With the increasing degree of automation in the industrial sector, electric control valves are being used more and more in various industrial production areas. The electric control valve generally includes the driver, accept the driver signal (0-10V or 4-20MA) to control the valve to adjust, but also according to the control needs, composed of intelligent network control system, optimized control to achieve remote monitoring.

      The flow characteristics of the electric control valve have linear characteristics, equal percentage characteristics and parabolic characteristics of three:
(1) Equal percentage characteristic (logarithmic) The relative travel of the percentile characteristic is not in a straight line relationship with the relative flow rate. The change in the flow rate caused by the change of the unit stroke at each point of the stroke is proportional to the flow rate at this point, the percentage of the flow rate change Is equal. So it has the advantage of small flow hours, flow changes small, large flow, the flow changes, that is, in different degrees of opening, with the same adjustment accuracy.

(2) linearity (linear) linearity of the relative travel and relative flow in a straight line relationship. The change in the flow caused by the change in the unit is constant. When the flow rate is large, the relative value of the flow is small and the flow rate is small. The relative value of the flow changes greatly.

(3) parabolic characteristics of the flow according to the two sides of the trip in proportion to change, generally with linear and equal percentage characteristics of the intermediate characteristics. From the above three characteristics of the analysis can be seen, on its regulatory performance speaking, to equal percentage of the characteristics of the best, its regulation is stable, good regulation. The parabolic characteristics and better than the linear characteristics of the regulatory performance, according to the requirements of different occasions, the selection of any one of the flow characteristics.