Adjust the composition of pneumatic valve and role & have spent < / div >

a: regulating the structure and the classification of pneumatic valve pneumatic valve, pneumatic valve, also known as control is the main type of actuator, by accepting conditioning control unit of the output control signal, from engine operation to change fluid flow. Adjust the pneumatic valve generally consists of actuators and pneumatic valves. If by their ticket enforcement agencies use the power, adjust the pneumatic valve can be divided into pneumatic, electrical, fluid movement three, namely to compressed air to power sources pneumatic valve, pneumatic control for electric power sources of electric control pneumatic valve, as a liquid medium ( Such as oil, etc. ) Pressure as the power of electric hydraulic pneumatic control valve, in addition, according to its function and feature points, and electromagnetic pneumatic valves, electronic style, smart, the scene of general linear pneumatic valve adjustment. Regulating pneumatic valve product type many, the structure is also varied, but also in constant updates and changes. In general pneumatic valve is common, can match with pneumatic operation organ, also can match with electric actuators or other actuators. 2: the role of pneumatic valve regulation mode choice to adjust the action of pneumatic valve mode only when choosing pneumatic actuators, the role of way through positive and negative effect and the positive role of pneumatic valve actuator portfolio formation. There are four that are positive (combination Gas closed type) , positive and negative, Gas type) And anyway, Gas type) And reflect ( Gas closed type) , through these four combination way have the function of regulating pneumatic valve open and close two kinds. For the choice of the ways of regulating pneumatic valve function, mainly from three aspects: a) Process safety; b) The characteristics of medium; c) Ensure product quality and economic loss is minimal. Three: regulate the flow of pneumatic valve, the choice of features: adjusting flow rate characteristics of pneumatic valve is refers to the relative flow and displacement through the pneumatic valve ( Pneumatic valve relative opening degree) The relationship between the ideal flow characteristic mainly has the percentage (such as straight line, Logarithmic) , parabolic and quick opening, etc. Four, characteristic curve and pneumatic valve core shape as shown in figure 1 and figure 2. Common ideal flow characteristic only percentage (such as straight line, Logarithmic) , quick opening three kinds. Parabolic flow characteristic between straight line and equal percentage, the percentage of properties such as generally available to replace, and quick opening feature is mainly used for two control and program control, thus regulating pneumatic valve features is, in fact, the choice of straight lines and equal percentage flow characteristic of choice. The choice of regulating pneumatic valve flow characteristics can be through theoretical calculation, but the method and equation are very complicated. Currently use experience more standard, concrete from the aspects to consider: (1) from the control system of regulating quality analysis and choice; (2) from the process piping is considered; (3) from the change of the load analysis. Choose good adjust the flow characteristic of pneumatic valve, pneumatic valve can be determined according to the flow characteristics of pneumatic valve core shape and structure, but for like pneumatic diaphragm valve, pneumatic butterfly valve, etc. , due to their structural characteristics, can not change the surface shape of pneumatic valve core to achieve the required flow characteristic, at this moment, can by changing the feedback of the pneumatic valve positioner CAM contour.