Exam Question
(a) Describe what would be the indications of crank case explosion in main engine. (4)
(b) Describe actions to be taken, if there is crank case explosion in main engine. (8)
(c) Describe means of prevention of crank case explosion. (4)
Class 4 (4th Engineer)
MEP
📅 Jul 2024
Reference Answer
### (a) Indications of Crankcase Explosion in Main Engine (4 Marks)
A crankcase explosion, while rare, is a serious incident on board a vessel. The indications can be immediate and severe, often resulting from the rapid combustion of an oil mist/air mixture within the crankcase. The key indications are:
* **Loud Detonation:** A distinctive, sudden, and very loud 'bang' or 'boom' sound, often followed by a rumble, indicating a rapid pressure rise and subsequent release.
* **Activation of Crankcase Relief Valves:** This is the primary safety mechanism activated. Large volumes of smoke, flames, or hot gases will be seen violently discharging from the spring-loaded crankcase relief valves located on the crankcase doors. The design of these valves includes flame traps to prevent flames from escaping and igniting surrounding areas.
A crankcase explosion, while rare, is a serious incident on board a vessel. The indications can be immediate and severe, often resulting from the rapid combustion of an oil mist/air mixture within the crankcase. The key indications are:
* **Loud Detonation:** A distinctive, sudden, and very loud 'bang' or 'boom' sound, often followed by a rumble, indicating a rapid pressure rise and subsequent release.
* **Activation of Crankcase Relief Valves:** This is the primary safety mechanism activated. Large volumes of smoke, flames, or hot gases will be seen violently discharging from the spring-loaded crankcase relief valves located on the crankcase doors. The design of these valves includes flame traps to prevent flames from escaping and igniting surrounding areas.
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