Abstract: A centrally controlled system for preventing overflow of fuels during loading operations includes dual processors either of which can take over the functions of the other processor when it fails. The system also includes full self-diagnostics and automatic testing to ensure that the warning lights and audible alarms at the loading compartments and the warning lights and audible alarms at the central location are operative during loading operations. If warning lights at the loading compartments are not visible due to obstructions, a voice synthesizer is used instead of lights at the loading compartments to announce the compartment identifier and the level of alarm reached. Floats in each compartment operate contacts when the level in the compartment reaches a first high level and when the level in the compartment reaches a second overfill level. In addition, if the level in any compartment reaches an overfill level, the power to the pumping station is automatically cut-off ceasing the loading operation.