We present an unconventional but high-performance differential pressure (DP) monitoring instrument constructed using a new class of sensor, i.e., a pulsating sensor developed in-house. This instrument of unique design is of industrial grade, and it is specially made for online monitoring of pressure in the Prototype Fast Breeder Reactor (PFBR), located in Kalpakkam, India. It measures pressure in two different ranges - 0 to 25 mbars (0 to 2.5 kPa) and 0 to 60 mbars (0 to 6.0 kPa) - using two specially designed capacitance-based robust probes made of stainless steel (Type 304L). The performance of this innovative instrument using both probes was thoroughly investigated at ambient room temperature as well as at elevated temperatures (above 30°C to 60°C) in order to assess its suitability for reactor application. The precision, sensitivity, response time, and lowest detection limit of measurement using this pulsating DP monitoring instrument are <0.01 mbars (0.001 kPa), 423 Hz/mbar (4230 Hz/kPa), [approximately]5 s, and 0.07 mbars (0.007 kPa), respectively. The influence of temperature up to 60°C on the measured parameters was found to be insignificant. A calibration technique has been evaluated to calibrate these pressure sensors.