The flow characteristic of the control valve is the relationship between the relative flow rate of the medium flowing through the control valve and its opening under the condition that the pressure difference between the both side of the valve remains constant.There are three flow characters: Liner characteristic, equal percentage characteristic and parabola characteristic of the regulating valve. The significance of the three characteristics is as follows:
(1) Equal Percentage Characteristic (Logarithm)
The relative stroke of equal percentage characteristic has no linear relationship with the relative flow. The change of flow caused by the change of unit stroke at each point of the journey is proportional to the flow at this point, and the percentage of flow change is equal. So its advantage is that when the flow rate is small, the change of flow rate is small, and when the flow rate is large, the change of flow rate is large, that is to say, it has the same adjustment precision in different openings.
(2) Linearity (Linearity)
The relative stroke of linear characteristic has a linear relationship with the relative flow rate. The change of flow rate is constant caused by the change of unit stroke. When the flow is large, the relative value of flow changes little, and when the flow is small, the relative value of flow changes greatly.
(3) Parabolic characteristics
The flow rate varies proportionally according to the two sides of the stroke, which has the intermediate characteristics of general characteristics and equal percentage characteristics.
