Fire Protection Type and Design
The two main purposes for fire protection systems within built environments are life safety and property protection. Equal consideration must be given to attempting to contain a fire while protecting a building’s occupants during their evacuation. Absolute safety from fire is not attainable, but means must be provided to minimize the potential for fire and the damage done by fire.
The systems and methods used today are constantly changing and improving to meet the requirements of project variations and challenges. Moreover, this chapter provides a basic outline for establishing the needed criteria to ensure fire safety via fire suppression within a building.
FIRE HAZARD EVALUATION
The first step in the design of an automatic sprinkler system is determining the overall fire hazard. The key factors affecting the overall fire
• Class of fire
• Occupancy and commodities classification
• Type of building construction and use
• Fire load and resistance rating
Fire Protection Type and Design – Classes of Fires
A generally accepted method of classification separates combustible materials into the following types:
• Class A fires: Ordinary combustible materials such as wood, cloth, paper, rubber, and many plastics (typical for wet-based sprinkler systems)
• Class B fires: Flammable liquids, combustible liquids, petroleum greases, tars, oils, oil-based paints, solvents, lacquers, alcohols, and flammable gases
• Class C fires: Fires that involve energized electrical equipment
• Class D fires: Combustible metals such as magnesium, titanium, zirconium, sodium, lithium, and potassium
• Class K fires: Fires in cooking appliances that involve cooking oils and fats
Class B, C, D, and K fires require specialized suppression systems based on the material that needs to be extinguished. Hence, the correct selection of an extinguishing agent is critical to controlling and extinguishing these types of fires.