The installed instrumentation such as the meters, indicators, controllers, lights, recorders and screen displays that came with the process. Operating Instruments Signals from some SCR controls and be fed to a temperature controller or DCS system to allow integrated control of the process. A look at a few specific types of instrumentation will provide clarification. Temperature Indicators and Controllers . Totally purge the plant of one or the other, or pay some day for scrap product or accidents.
Most instruments now are field convertible.
The scale range and resolution usually determine accuracy, so do not use a range greatly in excess of your working range. A hazard to accurate readings is a leaky bulb or capillary, which will default to low indication. Output Indication . If your final control device is a valve or actuator, make sure it feeds back a position signal, not a received control signal that you hope will be obeyed by the final control device. Also, note that even valve position knowledge does not necessarily imply a corresponding flow - or any flow at all.