Exam Question

### (a) Need to ensure that D.O. service tanks are not heated beyond a certain temperature.
Ensuring that Diesel Oil (D.O.) service tanks are not heated beyond a certain temperature is a critical safety measure on board ships, primarily due to the inherent flammability characteristics of fuel oils. This is mandated by international regulations and classification society rules to prevent fire and explosion hazards.
* **Flashpoint Definition**: The flashpoint of a volatile material is the lowest temperature at which its vapours will ignite in the presence of an ignition source. For marine D.O., the minimum flashpoint specified by SOLAS (Safety of Life at Sea) regulations and Classification Societies is generally 60°C.
* **Fire and Explosion Risk**: If D.O. in the service tank is heated to or above its flashpoint, the concentration of flammable vapours above the oil surface will increase to within the combustible range. Any accidental ignition source (e.g., static electricity, hot surface, spark, electrical fault) can then lead to an immediate fire or, in confined spaces, a potentially explosive mixture.