Regulating valve flow characteristics selection

Regulating valve flow characteristics selection

The regulating valve is mainly divided into two categories: electric regulating valve and pneumatic regulating valve. The flow characteristic of the regulating valve refers to the relationship between the relative flow rate of the medium flowing through the regulating valve and its opening degree under the regulation that the pressure difference at both ends of the valve is kept constant.

The flow characteristics of the regulating valve are linear, equal percentage and parabolic. The significance of the three fluence characteristics is as follows:

1. Percentage characteristic (logarithm): The relative stroke of the equal percentage characteristic is not linear with the relative flow. The change of the flow caused by the change of the unit stroke at each point of the stroke is proportional to the flow at this point, and the partial ratio of the flow change It is equal. Therefore, its advantage is that the flow rate is small, the flow change is small, and when the flow rate is large, the flow rate changes greatly, that is, the same adjustment precision is obtained at different opening degrees.

2. Linearity (linear): The relative stroke of the linear characteristic is linear with respect to the relative flow. The change in flow caused by changes in unit stroke is constant. When the flow rate is large, the relative value of the flow changes little, and when the flow rate is small, the relative value of the flow changes greatly.

3. Parabolic characteristics: The flow rate varies proportionally to the two sides of the stroke, and generally has an intermediate characteristic of linear and equal percentage characteristics.

Electric control valve daily small problem

When the servo amplifier of the electric control valve is in normal working condition, there may be the following three situations:

(1) When there is no input signal, there should be no output voltage.

(2) Open loop dead zone current ≤ 160μA (type II is 100μA).

(3) When the input signal is >240μA (type II is 150μA), the output load voltage is 205~220V?AC.

(4) The output voltage is basically symmetrical.