Abstract: A pressure monitoring apparatus (10) including features that simplify in-situ calibration procedures. A pressure monitoring module (12) of the apparatus is coupled to external pressure lines (14, 16) and an external electrical interface (24) via an easily removable monitoring module plug (32). The monitoring module can be disconnected from the pressure lines and external interface and then connected to a portable calibration module (42) by simply replacing the monitoring module plug with a calibration module plug (50). The calibration module plug provides an electro-pneumatic interface between the monitoring module and the calibration module. The monitoring module may be electronically interrogated and automatically calibrated via a processor of the calibration module. The monitoring module plug may be inserted onto the calibration module plug to provide actual system pressures to the now-calibrated apparatus for final documentation.