DOE-HDBK-1016/1-93ENGINEERING FLUIDS DIAGRAMS AND PRINTSEngineering Fluid Diagrams and PrintsIndicatorsand RecordersFigure 11 Indicators and RecordersIndicators and recorders areinstruments that convert the signalgenerated by an instrument loopinto a readable form. Theindicator or recorder may belocally or board mounted, and likemodifiers and transmitters thisinformation is indicated by thetype of symbol used. Figure 11provides examples of the symbolsused for indicators and recordersand how their location is denoted.ControllersControllers process the signal froman instrument loop and use it toposition or manipulate some othersystem component. Generally theyare denoted by placing a "C" inthe balloon after the controllingparameter as shown in Figure 12.There are controllers that serve toprocess a signal and create a newsignal. These include proportionalcontrollers, proportional-integralcontrollers, and proportional-integral-differential controllers. The symbols for these controllersare illustrated in Figure 13. Note that these types of controllers are also called signalconditioners.Figure 12 ControllersFigure 13 Signal ConditionersPR-02Rev. 0Page 12
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