Florida Wastewater Practice Test

What type of fire extinguisher should NOT be used on a petroleum oil fire?

1. Foam extinguisher

2. Dry chemical extinguisher

3. Pressurized water extinguisher

4. Carbon dioxide extinguisher

The correct answer is: Pressurized water extinguisher

A pressurized water extinguisher should not be used on a petroleum oil fire due to the nature of how water interacts with flammable liquids. When water is applied to a petroleum oil fire, it can cause the burning oil to spread, potentially resulting in a larger conflagration. This occurs because water is denser than oil and can cause the oil to separate and float, leading to an increased area of fire. In contrast, foam extinguishers create a barrier between the fuel and the fire, effectively smothering the flames and preventing the release of flammable vapors. Dry chemical extinguishers can interrupt the chemical reaction of the fire, and carbon dioxide extinguishers displace oxygen, suffocating the fire without causing splashing or spreading of burning oil. Thus, the use of water is inappropriate in this context, which is why it is necessary to recognize the dangers associated with using a pressurized water extinguisher on petroleum fires.