Pressurized systems at motor fuel dispensing facilities are those in which the pumping unit is located at a position remote from the pump island, typically inside or directly above the tank, and not in the dispenser itself.
When a dispenser is authorized to dispense fuel, the pump serving that dispenser is turned on. Since the pump may serve several other dispensers, however, its operation will pressurize all the pipe lines in the system carrying the same product. Leaks in pressurized piping can thus quickly reach a catastrophic level.
See also Suction system.