industrial instrumentation basics

Every flow meter is calibrated by the manufacturer for a specific set of service conditions before it ever reaches the field. How often — and how — it needs recalibration afterward depends heavily on the technology and the application: a DP transmitter on an orifice plate is calibrated very differently from a magnetic or Coriolis meter. This post covers both. Why Flow Meters Need Recalibration Recalibration needs depend heavily on how well the meter fits its application. Liquids that are corrosive, acidic, or abrasive gradually wear or coat internal components — orifice plate edges round off, electrodes foul, sensing diaphragms drift — and as that wear accumulates, measurement accuracy degrades even though the meter still produces a signal. Periodic calibration checks catch this drift before it turns into a real process or billing error. DP Transmitter (Orifice/Venturi) Calibration Procedure Most flow measurement in process plants is still DP-based — an orifice plate, venturi,...