Paper or wood fires are category A fires, and water extinguishers are commonly used to put them out. You could also use a multipurpose extinguisher for a paper or wood fire. Before attempting to put out any fire, you should be familiar with operating fire extinguishers and know the appropriate method of using an extinguisher. Always use the correct fire extinguisher for the category of fire you are attempting to extinguish.
Type A Fire Extinguishers
Water extinguishers are labeled as type A fire extinguishers and are large, silver extinguishers. The extinguisher is two-thirds filled with water and then pressurized with air. Paper and wood burn easily as they have low ignition temperatures, so a fire can quickly become out of control. Water extinguishers should never be used on deep fat fryer oil fires as the water may cause an explosion and the fire will spread more quickly. Additionally, water extinguishers should not be used on electrical fires as water is a conductor of electricity and use on electrical type fires could cause electric shock to the user.
Multipurpose Fire Extinguishers
Multipurpose fire extinguishers will be filled with dry chemicals and labeled according to the types of fires they will extinguish; for example type A and B or type A, B and C or B and C only. The type of fire these extinguishers can be used on is dependent upon the chemicals contained inside the extinguisher.
Fire spreads so quickly because it is a rapid reaction between combustible materials and oxygen, emitting heat, flames and smoke. Experts use a fire triangle drawing to depict the chemical reaction of fire. The base of the triangle consists of the fuel or combustible materials needed for the fire to spread; the two triangle sides consist of heat and oxygen. Heat is required to raise the temperature of the combustible materials to ignition point, and oxygen is needed to sustain the effect of combustion.
How Fire Extinguishers Work
Fire extinguishers work by taking out one element of the fire triangle. The fire extinguisher may cool down the heat element and disrupt the fire by stopping fuel from igniting. This is how water extinguishers work on paper and wood fires. Alternatively, fire extinguishers are used to coat the fuel with chemicals, stopping the reaction by that method, which is the way in which multipurpose extinguishers are used to put out fires. Carbon dioxide extinguishers displace the oxygen element of the fire. Each of the different types of fire extinguishers work in the best way for the category of fire it is used on.