Types Of Fire Extinguisher

Water and Foam fire extinguishers extinguish the fire by taking away the heat element of the fire triangle. Foam agent also separate the oxygen element from the other elements.
Water extinguishers are for Class A fires only - they should not be used
 on Class B or C fires. The discharge stream could spread the flammable 
 liquid in a Class B fire or could create a shock hazard on a 
 class C fire.
Foam extinguishers can be used on Class A & B fires only. They are not for use on Class C fires due to the shock hazard.

Carbon dioxide fire extinguishers extinguish the fire by taking away the oxygen element of the fire triangle and by removing the heat with a very cold discharge.
Carbon dioxide can be used on Class B & C fires. They are usually ineffective on Class A fires.

Dry Chemical fire extinguishers extinguish the fire by interrupting the chemical reaction of the fire triangle.
Today's most widely used type of fire extinguisher is the multipurpose dry chemical that is effective on Class A, B and C fires. This agent also works by creating a barrier between the oxygen element and the fuel element on Class A fires.

Wet Chemical is a new agent that extinguishes the fire by removing the heat of the fire triangle and Creating a barrier between the oxygen and fuel elements.
Wet chemical or Class K extinguishers were developed for modern, high efficiency deep fryers in commercial cooking operations. Some may also be used on Class A fires in kitchens.

Clean Agent extinguishers include the halon agents as well as the newer and less ozone depleting halocarbon agents. They extinguish the fire by interrupting the chemical reaction of the fire triangle.
Clean agent extinguishers are primarily for Class B & C fires. Some larger clean agent extinguishers can be used on Class A, B and C fires.

Dry Powder extinguishers are similar to dry chemical except that they extinguish the fire by separating the fuel from the oxygen element or by removing the heat element of the fire triangle.
Dry powder extinguishers are for Class D fires.

Water Mist extinguishers are a recent development that extinguishes the fire by taking away the heat element of the fire triangle. This is an alternative to the clean agent extinguishers where contamination is a concern.
Water mist extinguishers are primarily for Class A fires, although they are safe for use on Class C fires as well.

Cartridge Operated Dry Checmial fire extinguishers extinguish
 the fire primarily by interrupting the chemical reaction of the fire triangle.

 Like the stored pressure dry chemical extinguishers, the multipurpose dry chemical is effective on Class A, B and C fires. This agent also works by creating a barrier between the oxygen element and the fuel element on Class A fires.