When a single flange differential pressure transmitter is in operation, the isolation diaphragms on the high and low pressure sides and the filling fluid transmit the process pressure to the filling fluid at the center, which in turn transmits the pressure to the sensing diaphragm at the center of the delta chamber sensor. The sensing diaphragm is a tensioned elastic element whose displacement varies with the differential pressure applied (for GP gauge pressure transmitters, atmospheric pressure acts as if applied to the low-pressure side of the sensing diaphragm). AP absolute pressure transmitter maintains a reference pressure on the low pressure side at all times. The maximum displacement of the sensing membrane is 0.004 inches (0.10 millimeters). The displacement is proportional to the pressure. The amplified circuit of the fixed plates of the two capacitors measuring the membrane is linearly converted into a 4-20mA DC two-wire current, voltage, or digital HART (High Speed Addressable Remote Transmitter Data Highway) output signal.