The differential pressure sensor PMP is used for controlling and measuring the differential pressure of air or non-corrosive gases. It is mainly used for the monitoring of filters or filter cartridges measuring the pressure difference before and after the filter chamber. Cleaning cycles can be determined by means of the programmable relay. If a predefined differential pressure is reached, the rinsing process can be started e. g. automatically via the solenoid valves, and the second relay produces an alarm if the differential pressure increases further on. Thus, the cleaning cycles can be optimised and considerable quantities of compressed air can be saved. The differential pressure is shown on a four-digit display. For a remote transmission, a 4 - 20 mA output signal is provided. The device is controlled by a micro processor. Relay, hysteresis, time delay of the relays and analogue output are freely programmable.