Which class ratings do not include common numerical ratings as part of their classification?

Class C, Class D, and Class K fire extinguishers are categorized differently than other classes. This classification is important for understanding how these extinguishers are used and what types of fires they are designed to combat.

Class C extinguishers are specifically designed for electrically energized fires and do not include numerical ratings because the hazards of electrical fires can vary greatly depending on the voltage and equipment involved. Instead, the effectiveness of these extinguishers relies on the type of agent used, which must be non-conductive to ensure safety when used near electrical sources.

Class D extinguishers are used for flammable metals, which also do not have a standard numerical rating system. This is due to the unique nature of metal fires, which can behave unpredictably depending on the specific metal involved, necessitating specialized extinguishing agents.

Class K extinguishers are intended for cooking oil and grease fires common in commercial kitchens. Similar to Classes C and D, they do not carry numerical ratings. The distinction here is essential because cooking fires involve specific types of oils that require particular suppression methods.

In contrast, Classes A and B fire extinguishers do have numerical ratings that represent their effectiveness against ordinary combustible materials and flammable liquids, respectively. Understanding these classifications is