Oilers/Plant Tenders (HHC) Civil Service Practice Exam

How can crankcase explosions in an internal combustion engine be prevented?

1. By increasing ventilation

2. By keeping air out of the crankcase

3. By reducing fuel temperature

4. By using lighter oils

The correct answer is: By keeping air out of the crankcase

Preventing crankcase explosions in an internal combustion engine primarily involves controlling the conditions that could lead to an explosive atmosphere within the crankcase. Keeping air out of the crankcase is crucial because the presence of air, which contains oxygen, can lead to the formation of explosive mixtures with fuel vapors or oil mist. By maintaining a sealed environment, the opportunity for such mixtures to form is minimized, significantly reducing the risk of an explosion occurring. The other options, while they may support engine efficiency or safety in other contexts, do not directly address the fundamental cause of crankcase explosions. For instance, increasing ventilation could introduce fresh air and oxygen into the crankcase, which could actually exacerbate explosion risks. Similarly, reducing fuel temperature or using lighter oils does not have a direct correlation with preventing exposure to explosive mixtures; instead, it may contribute to performance changes rather than enhancing safety against explosions.