Exam Question

(a) The Perforation of a High-Pressure Fuel Pipe
To reduce fire hazards in case of a leak in the high-pressure (HP) fuel line (between the fuel pump and injector), jacketed fuel pipes are used for HP fuel delivery lines. If there is a leak, the heated fuel may escape as a jet or spray which, upon contacting a hot surface, could ignite. However, in a jacketed fuel line , any leaked fuel is safely routed away through an outer casing .
In MAN B&W type engines, each fuel pump’s high-pressure jacketed leak-off space is connected via a drain line to a common drain tank . This tank includes a level switch and an overflow pipe with a small drain bore below it.
Minor leakages : The small drain bore allows the oil to escape without activating the level switch.