What does the number on fire extinguishers indicate?

The number on fire extinguishers indicates the extinguisher's fire rating, which reflects its effectiveness against different types of fires. For example, a Class A rating relates to ordinary combustibles like wood and paper, while Class B pertains to flammable liquids. The number preceding the letter typically indicates the amount of extinguishing agent available; for instance, a 2A rating means the extinguisher can handle twice the fire risk of a 1A rating. Understanding these ratings helps users select the appropriate extinguisher for specific fire hazards.