FIRE SYSTEM

• Fire is a combustion reaction that requires oxygen (air), heat, and a fuel.
• There are four stages in the progression of a fire: ignition, flame spread, flashover, and consumption.
• Ignition requires the proper blend of oxygen (air), heat, and fuel.
• The second stage is flame spread, which is characteristic of rapid crawling tongues of fire that lick across the surface of walls, ceilings, floors and supporting timbers.
• As the fire intensifies, the heated material releases large volumes of volatile gases into the air. When the mixture of gases and air reach critical proportions, the material ignites in a great ball of fire called the flashover stage
• The final stage in the burning sequence is the fiery consumption of the material itself as it burns to ash.
• Classifications of Fires Generally, fires are classified into four groups by type of fuel:

  Group A: Ordinary combustibles (e.g., wood, paper, plastics, trash, grass, and so on)

  Group B: Flammable liquids (e.g., gasoline, oil, grease, acetone, and so on)

  Group C: Electrical equipment (e.g., any electrical wiring, connection, equipment, and so on)

  Group D: combustible metals (e.g., potassium, sodium, aluminum, magnesium, and so on)
• Building fires typically begin with the ignition of building contents (e.g., a smoldering cigarette sets fire to upholstered chair or mattress).
• Fire-resistive (Type I) construction, with its concrete and protected steel walls, floors, and structural framework, was initially intended to confine a fire by its method of construction— that is, by containing the fire with noncombustible wall, ceiling, and floor assemblies so it is confined to one floor or one space on a floor
• Noncombustible (Type II) construction is also built of noncombustible steel or concrete walls, floors, and structural framework; however, the roof covering is combustible, which can burn and spread fire.
• Ordinary (Type III) construction is built of noncombustible masonry-bearing walls, but the floors, structural framework, and roof can be made of wood or another combustible material.
• Heavy-timber (Type IV) construction is built of a structure that consists of large timbers. In this type of construction, a wood column cannot be less than 8 in thick in any dimension and a wood beam cannot be less than 6 in thick.
• Wood-frame (Type V) construction is the most combustible of the five types of building construction.
• Passive fire protection in buildings involves constructing walls, floors, ceilings, beams, columns, and shaft enclosures so they can resist, control, and contain the damaging effects of a fire.
• A principal objective of fire-resistive construction is to use materials and construction assemblies that contain the fire in a small area and confine the fire in the room or area for a specific period of time.
• Compartmentalizing means separating a building into compartments so that if there is a fire, the fire damage is confined to certain a room or certain section of the building only.
• Fire walls are fire-rated walls that form a required barrier to restrict the spread of fire throughout the building. They serve as a means of dividing a large structure into compartments.
• A fire separation is similar to a fire wall except that it does not extend from the foundation to the roof assembly.
• A firestop is a specific construction technique consisting of all materials that fill the opening around penetrating items such as cables, cable trays, conduits, ducts, and pipes and their means of support through the wall or floor to prevents the spread of fire.
• An intumescent material swells, enlarges, inflates, and expands when exposed to heat. Fire-protective intumescent coatings are applied like paint to structural steel members at a thickness that ranges from 0.03 to 0.4 in (0.8 to 10 mm).
• Fire doors are typically of steel or solid wood construction and are installed with specially tested components including closers, latching hardware, and fire-rated glass lites (windows).
• Fire-resistant insulating glass contains flames and inflammable gas for a longer period of time and prevents not only the transmission of flames and smoke but also of heat to the other side of glazing.
• Active fire protection systems include standpipe, sprinkler, and spray systems designed to extinguish the fire outright or control the fire by delaying its damaging effects.
• A standpipe system is an internal piping network connected to fire-hose stations that are used to rapidly suppress a fire.
• The hose is usually stored on a quickrelease rack called a hose reel.
• Fire suppression systems are intended to extinguish or control a fire.
• Smoke control systems are designed to limit the spread of smoke to maintain passable occupant egress routes for a given period of time and to aid firefighters in fighting the fire.
• An automatic fire protection system provides a warning to occupants of the building, notifies emergency personnel responding to the alarm, and activates fire suppression systems to reduce the growth rate of a fire or the movement of smoke.
• An automatic sprinkler system consists of the sprinkler heads and a network of pipes placed in a horizontal pattern near the ceiling and is designed to automatically dispense water on a fire.
• Automatic sprinklers are devices that open automatically to discharge water when an excessive temperature is detected
• An alarm valve and gate valve serve to control flow in the network of sprinkler system.
• A gravity storage tank may be located on the top of a building or on a tall tower.
• Pressure tanks are often used where there is enough water from a supply source, but the water pressure is too low or in tall buildings that need the extra water pressure to supply the highest line of sprinklers or the highest line of hoses.
• A fire pump is a part of a fire sprinkler system’s water supply in high-rise installations where the local public water system cannot provide sufficient pressure, where systems require high pressure at the fire sprinkler in order to flow a large volume of water (large warehouse or manufacturing plant), and where water is from a storage tank.
• Portable fire extinguishers can be used to put out most fires in their early stages. They are classified according to their ability to handle specific classes and sizes of fires.
• Fire alarm systems detect products of combustion, such as smoke (aerosol particulate), heat, and light, and provide early occupant notification to allow the safe egress of the occupants.
• A smoke alarm is a fire-safety device that detects the products of combustion and gives off an audible and/or visual warning to building occupants.
• A smoke detector is a sensing device that identifies products of combustion in air.
• . Heat detectors are a sensing device that recognizes a high temperature or a rapid increase in temperature.
• Fixed-temperature heat detectors signal an alarm after the temperature at the detector reaches a set value.