Fire Extinguisher :
Each fire extinguisher has its own symbolic notation, that is a special geometric symbol to make it easier for you to identify the extinguisher type. They also have some additional information necessary in case of this or that class of fire fighting.
Class A fire extinguishers, for example, have the green triangle on them and also the special numerical rating, showing the amount of water this extinguisher holds and the amount of fire it is able to extinguish.
Class B fire extinguishers are marked with the red square and have the numerical rating indicating the approximate area of fire (in square feet) it is able to extinguish.
Class C fire extinguishers are marked with the blue circle, but they don’t have any numerical rating. As a rule they contain the non-conductive extinguishing agent, because they are often used for electrical fire fighting.
Class D fire extinguishers have the yellow decagon on them and are mostly regarded as the part of chemical laboratory firefighting equipment. They also don’t have any numerical rating on them. There are also class K fire extinguishers, marked with the black hexagon. They are intended for the fighting the fire, caused by any cooking oils, fats or trans-fats combustion and are highly recommended for restaurant or cafeteria kitchens.