In case of a fire, what substance should NOT be used for extinguishing oil-based fires?

Using water to extinguish oil-based fires is highly dangerous and can actually exacerbate the situation. When water is applied to an oil fire, it can cause the oil to spread, as water is denser than oil and will sink beneath it. This can lead to a larger area of flames and increased risk of injury or damage.

In contrast, other extinguishing agents such as dry chemical fire extinguishers, foam extinguishers, and carbon dioxide extinguishers are designed to effectively tackle oil-based fires. Dry chemicals can smother the flames and interrupt the chemical reaction of combustion, while foam extinguishers create a barrier between the fuel and the oxygen, helping to suppress the fire. Carbon dioxide extinguishers work by displacing oxygen in the vicinity of the fire, effectively starving it of the material it needs to continue burning.

Thus, the recommendation is clear: avoid using water on oil-based fires and instead opt for appropriate fire extinguishing agents.