Abstract: Safety control system with electronic data acquisition for the inline regulation of the max. permissible pressure during refueling of the aircraft. With this procedure the driving speed of the feed pump is regulated to so that no higher refueling pressure than 35 respectively 50 PSI can develop. The diesel engines were equipped already some years ago with an interface for an external control of number of revolutions. www.manted.de The received messages for the control modules are given binarily with parameters. In case of leakages within the pressure range or deviations from the differential pressure the refueling of the aircraft is interrupted automatically. The inline regulation examines itself independently by the audible change of the number of revolutions of the engine during each aircraft refueling. If one single person does the refueling of the aircraft the automatic control is of significant importance.

Abstract: A spring-loaded differential pressure gage, particularly for testing the components of means for admitting fuel to the tanks of aircraft, has an upright glass cylinder for a reciprocable glass piston with a ring-shaped index which is movable relative to a fixed scale. The heat expansion coefficient of the material of the cylinder is identical with that of the material of the piston. The higher- and lower-pressure cylinder chambers are respectively located above and below the piston, and the piston is suspended on the stronger of two helical tension springs. The upper end of the weaker tension spring is connected to a fixedly mounted plug and the lower end of the weaker spring, as well as the upper end of the stronger spring, is connected to a second plug which is slidable along an upright guide rod having a stop at the lower end thereof. When the pressure of fluid in the upper chamber rises, the weaker spring expands and the stronger spring merely pushes the piston toward the lower end of the cylinder.