What is one of the risks posed by flammable vapors in fuel oil systems?

Flammable vapors in fuel oil systems present significant hazards, primarily because they can lead to fire or explosion hazards. When flammable vapors accumulate, they create an environment where a spark or heat source can ignite them, leading to potentially disastrous outcomes such as explosions or uncontrollable fires. This risk is particularly acute in areas where fuel is stored or handled, making it crucial for safety protocols to prioritize the management of vapor concentrations and ensure proper ventilation.

While the other options do address potential issues related to fuel oil systems—such as the possibility of corrosion, structural integrity, and fuel delivery inefficiencies—the immediate and most serious consequence of flammable vapors is the risk of fire and explosion. This risk not only endangers lives but also damages facilities, necessitating stringent safety measures and regulations within the industry to mitigate these dangers.