For which gas is it vital to use a Class B fire extinguisher?

Using a Class B fire extinguisher is essential for extinguishing fires fueled by flammable liquids and gases, which includes gasoline. Gasoline is categorized as a flammable liquid due to its ability to ignite easily and burn rapidly. Class B extinguishers are specifically designed to tackle fires caused by substances like gasoline, oil, and other hydrocarbons effectively. Their extinguishing agents, such as foam or dry chemical, are formulated to suppress flames by creating a barrier between the fuel and the oxygen, or by disrupting the combustion process.

While propane, hydrogen, and natural gas are also flammable gases, they may require different methods or extinguishers due to their specific burning characteristics and the nature of their flames. Thus, while Class B might be used in some contexts with these gases, particularly with propane, gasoline remains the most critical substance for which a Class B extinguisher is vital.