Description The PR-285 is designed to measure very low differential pressure generated by annubar, venturi, and other liquid flow measurement devices. The transducer can measure differential pressure down to 0 to 20 inches water column and, at the same time, can withstand up to 300 PSIG of system static pressure. Within the transducer, static pressure is transmitted through isolator diaphragms and silicone fill fluid to a sensing diaphragm. The sensing diaphragm, located within the electronics housing, is a stretched spring element that deflects when differential pressure is applied to it. The spring's displacement is proportional to the differential pressure. Two capacitor plates, located at either ends of the spring, convert the differential capacitance detected between the spring and plates into a 4 to 20 mA signal.