Adjust the three characteristics of pneumatic valve

regulating pneumatic valve for regulating the flow of medium, pressure and liquid level. According to adjust the position signal, the automatic control of pneumatic valve opening, so as to achieve the adjustment of the medium flow rate, pressure and liquid level. Regulating pneumatic valve points electric pneumatic valve, pneumatic regulating pneumatic valve and hydraulic pneumatic valve, etc.
regulating pneumatic valve consists of electric actuators or pneumatic actuators and regulating pneumatic valve in two parts. Adjust and usually can be divided into direct single-seat regulating pneumatic valve and direct two-seater type adjustment pneumatic valve two kinds, the latter has a large flow capacity, unbalanced and the characteristics of stable operation, so often especially suitable for large flow, little pressure drop and leakage.
flow capacity Cv selection in regulating pneumatic valve is one of the main parameters, to adjust the flow capacity of pneumatic valve is defined as: when regulating pneumatic valves, pneumatic valve pressure difference on both ends. G/cm for MPa, fluid density, regulating the flow of pneumatic valve number per hour flow diameter, called flow capacity, also known as the flow coefficient, expressed as a Cv, unit for t/h, Cv value of the liquid press type calculation.
according to the flow capacity Cv value look-up table size, you can determine to adjust nominal size of the pneumatic valve DN.
adjust the flow characteristic of pneumatic valve, pneumatic valve is in both ends of the pressure difference under the condition of constant, the medium flows through adjusting the relative flow pneumatic valve and the relationship between its opening. Adjust the flow characteristic has a linear characteristic of pneumatic valve, such as the percentage and parabolic characteristics of three. The meaning of three kinds of injection flow characteristic is as follows:
( ） Such as percentage of features, Logarithmic) Percentage characteristics such as relative trip and no linear relationship between relative flow in the process of every point unit running change caused by the flow of change is proportional to the flow of this point, the percentage of the flow rate change is equal. So it has the advantage of traffic hours, changing flow is small, large flow, the flow rate change is big, is also on the different opening, has the same accuracy.
（ ） Linear features, Linear) Linear characteristic of relative stroke and the relative flow into a linear relationship. Unit trip caused by the changes in the flow rate change is constant. Large flow, the flow relative changes little, traffic hours, flow relative change is big.
（ ） Parabola changes flow according to the schedule 2 is proportional with linear and roughly equal percentage in the middle of the properties.
can be seen from the analysis of the above three kinds of characteristic, its regulation performance, is the optimal with characteristics such as percentage, its regulation stability, good regulation performance. And parabolic characteristics than the linear characteristic of regulating performance is good, can according to the requirement of the application, choose any of them a flow characteristic.