The introduction of pneumatic control valve

Pneumatic control valve for regulating the flow of medium, pressure and liquid level. According to adjust the position signal, automatic control valve opening, so as to achieve the adjustment of the medium flow rate, pressure and liquid level. Electrical pneumatic control valve, pneumatic control valve pneumatic control valve of pneumatic and hydraulic pneumatic control valve, etc. Pneumatic control valve consists of electric actuators or pneumatic actuators and pneumatic control valve of two parts. Pneumatic control valve is usually divided into direct single-seat type pneumatic control valve and the pass-through two-seater type pneumatic control valve, 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 is to choose one of the main parameters of pneumatic control valve, pneumatic control valve of the flow capacity is defined as: when the pneumatic control valve fully open valve pressure difference on both ends of 0. 1 mpa, the fluid density is 1 g/cm3, pneumatic - valve on the number of traffic flow diameter per hour, 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 the nominal size of the pneumatic control valve DN. Pneumatic control valve flow characteristic, it is on both ends of the valve differential pressure under the condition of constant, medium flows through the pneumatic control valve of the relation between relative flow and its opening. Pneumatic control valve flow characteristics have a linear features, such as percentage and parabolic characteristics of three. The meaning of three kinds of injection flow characteristic is as follows: ( 1) 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. （ 2) 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. （ 3) 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.