Workplace Fire Safety and Classification

Fire Protection and Energy Safety

Fire protection must be understood as the set of devices to be taken to avoid injury or damage that fire can cause in a workplace. The employer is obliged to take appropriate measures in the fight against fires. On one hand, this leads to the means to prevent or catch fire if it spreads. On the other hand, it establishes within the emergency plan how to proceed with a rapid evacuation to be effective for personnel. For this practice, fire prevention and evacuation drills should be performed periodically.

Basic Concepts of Fire

To prevent or combat an outbreak of fire, one must know some basic concepts, such as the fact that fire is the fire spread. For a fire to exist, you need a subsequent reaction between an oxidizer element, a fuel, and a source of heat. This process is called combustion. The factors involved in the combustion process are represented graphically in the so-called fire triangle. Oxidizer, fuel, and heat must be present at the same time so you can start the elimination of the fire. The elimination of any side of the triangle determines the disappearance of the fire. Recently, it has been believed that there is also a fourth factor involved in the process: the reaction of the combustion gases with one another and with the oxygen in the air. This is called a chain reaction. With this new factor, the triangle becomes a tetrahedron or square of fire.

• The fuel: Any substance that can burn in the presence of an oxidizer and a source of heat. It can be liquid, solid, or gaseous.
• The oxidizer: A mixture of gases in which oxygen is in sufficient proportion to produce the most normal combustion. The oxidizing air contains about 21% by volume of oxygen.
• The heat: It is not enough to have air and fuel; there must be a focus to provide sufficient heat for the fire to occur.
• The chain reaction: If the fuel, oxygen, and heat occur at the same time, it starts the combustion, which involves heat release, which is partly absorbed by the fuel and partly disintegrates in the medium.

Classification of Fires

In order to choose the most useful extinguishing agent, the different types of fire are classified according to the nature of the fuel as follows:

• Class A: Fire of common solid materials, usually organic types, whose combustion results in the formation of coals.
• Class B: Fire involving liquid fuels that form flames (oil, benzene, paints, etc.).
• Class C: Gas fire (propane, butane, methane, etc.).
• Class D: Fire of reactive metals and chemical compounds, which require special extinguishing systems (alkali metals, aluminum powder, etc.).
• Class E: Fire that occurs through the agency of electricity.