任何流体过程的流量或压力控制要求有三个独立的功能:测量、计算和校正。这些功能通常各由过程传感器,调节器和调节阀来完成。传感器和调节器通常都是线性仪表:即输入和输出的比是常数。但是,凋节阀通常应具有某些特性,使其在控制范围内具有最好的稳 Flow or pressure control of any fluid process requires three separate functions: measurement, calculation and calibration. These functions are usually done by process sensors, regulators and regulating valves. Sensors and regulators are usually linear meters: the ratio of input to output is constant. However, the valve should usually have some of the features, so that it has the best control in the stable