Class 4 (4th Engineer) MEKG 📅 May 2024

Exam Question

Write short notes on the following:

(a) Need to ensure that D.O. service tanks are not heated beyond a certain temperature (4)

(b) Importance of the level of the F.W. compensating tank for jacket cooling of main engines as an indicator of impending trouble (4)

(d) Necessity for a proper check of all engine room parameters before taking over of watch (4)

Reference Answer

#### (a) Need to ensure that D.O. service tanks are not heated beyond a certain temperature
The temperature of Diesel Oil (D.O.) in service tanks must be strictly controlled for reasons of safety, operational efficiency, and machinery integrity.
* **Safety (Flash Point Limitation)**: This is the most critical reason. SOLAS regulations mandate that the temperature of any fuel oil in a service tank must be maintained at least 10°C below its flash point. The typical flash point for Marine Gas Oil (MGO/D.O.) is >60°C. Overheating the fuel can cause it to release flammable vapors into the tank's ullage space. This creates an explosive atmosphere, posing a severe risk of fire and explosion, especially in an enclosed engine room.
* **Viscosity and Lubricity Control**: Unlike heavy fuel oil, D.O. does not typically require heating to reduce viscosity. Heating is only necessary in cold climates to prevent waxing. Excessive heating drastically reduces the fuel's viscosity and lubricity. This leads to:

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