What is a class B fire extinguisher?

Class B fire extinguishers are designed to put out fires related to burning liquids and gases such as gasoline, kerosene, butane, and propane. A class B extinguisher will typically be classified with a numerical rating which indicates the number of sq feet it can extinguish. Monoammonium phosphate will typically smothers the fire, as the sodium bicarbonate creates a chemical reaction that puts out the fire. Most standard fire extinguishers will be a combination of A, B, and C.