Fire Alarm Monitoring Systems and Suppression Components
Detection of a fire can include heat detection, smoke detection, infrared detection, and gas detection equipment. There are several types of fire alarm systems and remote monitoring services available today in the residential, commercial, and industrial markets. Early fire detection and warning of building occupants is the most significant factor in preventing loss of life. A fire alarm system installed in an occupancy where people normally sleep would be different than a manufacturing facility or educational institution. The alarm system not only monitors these sensing devices but can control other functions in a building, such as air movement, doors, elevators, lighting, and water flow. Fire alarm systems range in complexity from simply detecting fire and warning occupants, to managing smoke and water to sprinklers to create a safe egress route and tenable environment for occupants and fire personnel. The fire alarm system is one component of fire detection and alarm systems. This article will review common alarm systems and several other fire protection systems, which will include fire suppression components and basic water supply.
Fire Alarm Systems
A fire alarm system in comprised of multiple components: Fire Alarm Control Panel (FACP), primary power supply, secondary or backup power supply, initiating devices, notification appliances, and a remote off-site reporting system.
The “brain” of the system, the FACP contains electronics and a power supply that energizes detection devices and monitors the system. It receives signals back from initiating devices such as pull station, smoke detectors, water flow sensors, heat detectors, and tamper switches. The FACP supervises the system for actual alarms or “trouble” situations, such as a tamper switch activation, and notifies the appropriate people. This system can also activate relays that control elevators, lighting, air movement, door closing, voice announcement systems, and more. There can also be remote annunciators located throughout the premise or property that allow remote control or display of information in different locations.
The FACP is powered by a primary power supply, usually a dedicated circuit off the main electrical feed, backed up by a battery or secondary power source, such as a generator. Notification appliances are strobe lights, audible alarms, horns, bed shakers, voice announcements, or a combination of these devices. Remote or off-site reporting is a feature of monitored systems where it uses a dedicated phone line or a wireless radio connection to report trouble or an alarm condition to an alarm monitoring company, who then notifies the responsible person of the property and the local fire department.
Fire alarm systems can be configured in several ways. A protected premise or local systems are designed to notify only occupants on the immediate premise and do not make any remote notifications. Proprietary systems are used to protect large commercial or industrial buildings as well as high-rise buildings or large campuses with multiple buildings. Each location has its own system–all are wired into one location that is monitoring continuously by on duty staff who can perform various tasks in the event of a fire and notify the fire department manually.
A central station service is monitored by a contracting company continuously. When an alarm is activated, employees contact the fire department and person responsible. A runner is required who can respond to the location, per NFPA 72 requirements.
Fire hydrants are the primary source of water for emergency service personnel for fire suppression. Fire hydrants are found in two different configurations: dry-barrel and wet-barrel. Dry-barrel hydrants are required in areas that are subject to freezing temperatures. The hydrant is empty until the valve is turned on. There is a drain located in the bottom to drain water out when the valve is turned off. The valve is turned using a nut on the bonnet or top of the hydrant, which turns a long shaft that goes down the middle of the shaft, underground and below the freeze line, to a valve connected to the water main. These hydrants must be completely opened or completely shut. Leaving the valve partially open may erode the earth by water escaping out of the drain hole at the base of the hydrant. Dry-barrel hydrants are typically configured with two 2.5-inch outlets and one 4.5-inch outlet. Others may be found with just two 2.5-inch outlets. These types are low-flow and not suitable for large industrial fires. Hydrants configured with a 4.5-inch pumper or steamer outlet offer more water flow. Wet-barrel hydrants can be found in locations where there is no freezing weather expected, such as in California or Florida. Operating nuts on the hydrant extend through the side of the barrel, one for each outlet.
Both types of hydrants are connected to the water main by a short pipe called a branch. The branch has a foot valve that can be turned off with a key, to stop water supply to the hydrant for maintenance or repair. Hydrants may be color coded to indicate their rated flow rates and installed in convenient locations for use by the fire department. Hydrants need to be positioned appropriately and accessible with proper height and ground clearance, free of obstructions such as shrubs or vegetation. The location and distance between fire hydrants change, depending on location, such as residential, industrial, or commercial areas.
Portable Fire Extinguishers
Portable fire extinguishers are one of the most common devices available for fire protection. Fire extinguishers can be found in a variety of locations including homes, kitchens, boats, passenger vehicles, mechanical rooms, public assemblies, and more. They are often the first line of defense in the event of a fire. Portable fire extinguishers are classified for certain types of fires; one type of extinguisher is not effective on all types of fires. There are labels affixed to the shell that display a pictorial icon, which gives a graphic example of the type of fire it is used for. There is also a lettering system in place to classify extinguishers:
Class A Fires—ordinary combustibles, such as wood, paper, cloth, rubber, and many types of plastics. These fires are extinguished by cooling, smothering, insulating, or inhibiting the chemical reaction.
Class B Fires—fires involving flammable or combustible liquids and gases, including greases and similar fuels. These fires are extinguished by removing oxygen, smothering, and insulating to inhibit the chemical reaction.
Class C Fires—involve energized electrical equipment. The chemical agent used is nonconducting to reduce the risk of shock to the operator. Once the electrical hazard is removed, the fire becomes a class A for B type fire.
Class D Fires—combustible metals, such as magnesium, potassium, sodium, titanium, and zirconium. An agent that absorbs heat is necessary to smother the fire; the agent can be applied by shovel or an extinguisher.
Class K Fires—cooking oils and fats. These extinguishers work by forming a barrier and smothering the fire.
Extinguishers come in various sizes and are rated with a numbering system that indicates the square feet of fire that the device can extinguish by an untrained person. Extinguishers must be properly chosen and placed throughout the occupancy.
In addition to proper selection and distribution, the extinguishers must be conspicuous, readily visible, easily accessible, and mounted properly so that they are not an injury hazard and to avoid damage.
The following factors must be considered:
They must be visible with clear signage.
They must not be blocked or obstructed by storage equipment.
They must be located near exit points and entrances.
They must be located along normal paths of travel.
The physical environment is also important. Temperature is a concern because the tested operating range is between 40°F and 120°F. Other environmental factors can adversely affect a extinguishers performance, such as rain, snow, and corrosive fumes.
Extinguishing agents available in portable fire extinguishers are the following:
Water—used on ordinary combustibles, works by cooling the burning fuel. Not recommended for electrical fires.
Aqueous film forming foam (AFFF)—produces air foam and floating film on the surface of a liquid fuel, suitable for class A and B fires. Works by cooling and penetrating the fuel.
Film forming fluoroprotein (FFFP)—foaming agent similar to AFFF. Usually diluted in water 3 to 6 percent and is effective on class A and B fires. Usually located where water-soluble flammable liquids are being used.
Carbon dioxide—a colorless and noncombustible gas that smothers the fire by establishing a gaseous blanket between the fuel and environment while displacing oxygen.
Halon—contains atoms from one of the halogen series of chemicals, such as fluorine, bromine, and iodine. Effective on class A and B fires. Does not leave a residue but is harmful to humans and the environment.
Dry chemical—powder agent also suitable for outdoor fires and may consist of sodium bicarbonate, potassium bicarbonate, urea bicarbonate, and monoammonium phosphate. An advantage is reach of the chemical compared to chemical or gas extinguishers and the multi-purpose use. Cleanup is difficult after discharging one, which is why outdoor use is suitable.
Sodium bicarbonate—treated to be water repellent and has no toxic effects. Suitable for class B and C materials.
Potassium bicarbonate—also known as Purple K, twice as effective as sodium bicarbonate. Quickly knocks down flaming combustion. On class A fires, it creates a solid coating and smothers the fire.
Monoammonium phosphate—can be used on Class A, B, and C fires and forms a solid coating on burning materials and effectively smothers the fire.
Dry powder agents—used on combustible metal fires by absorbing heat. Wet chemical agents—used to extinguish fires involving cooking equipment and the misting action prevents splashing of burning animal fats and vegetable oils when applied.
Portable fire extinguishers are available in stored-pressure, cartridge-operated, and pump-operated versions. They must be inspected regularly, at least monthly, to include proper location, easy access, inspection tag current, horn and nozzle intact, lock pin present, signs of physical damage, pressure gauge in green, and appropriate type of extinguisher. Maintenance and servicing must be done by trained personnel from a third party and in accordance with the manufacturer label. An extinguisher with any issues found during inspection or that has been discharged must be immediately taken out of service and tested.
Standpipe and Hose Systems
Standpipe and hose systems provide a means for rapidly supplying water and deploying fire hoses throughout remote locations in a structure. Their presence reduces the time it takes fire suppression personnel to deploy hoselines and reach fires in various parts of a building.
Components of a standpipe and hose system are hose stations, water supply, water-flow control valves, risers, pressure-regulating devices, and a fire department connection. These systems are classified in three ways:
Class I—primarily used by fire suppression personnel who are trained in handling large hoselines. These hoselines can be 1.5 to 2 inches in diameter and have high flow.
Class II—designed for use by building occupants who are trained in its use or by fire suppression personnel. These hoselines are 1.5 inches in size.
Class III—combines the features of class I and II systems by providing preattached hoselines in addition to 1.5- and 2-inch hose connection discharges for fire personnel to attach their hoses to. The types of standpipes include automatic wet, automatic dry, semiautomatic dry, manual dry, and manual wet.
Fire Department Connections
Each Class I or III standpipe system requires one or more fire department connections (FDCs) on the exterior for a fire pump to connect to and supply or supplement the system. Some installations may have a dedicated watery supply and pump, some may be dry, and some are boosted or supplemented by a fire apparatus. In high-rise structures, there are multiple FDCs on the building and labeled by floor or zone. FDCs are exterior water intakes that connect to the standpipe system and require at least two 2.5-inch inputs or one 4-inch port. First-due fire companies must be familiar with locations of the FDCs, fittings, and sizes, including locations of fire hydrants in their response areas. This knowledge will prevent delay and allow responding apparatus to properly position themselves so that they are ready to charge the system and provide water to crews entering the building. FDCs can serve standpipes installed throughout a building or serve an automatic sprinkler system and must be labeled “STANDPIPE” or “AUTOSPKR” and indicate the zone or area they serve. Training and testing are required so that fire personnel don’t under or overcharge the system.
Sturzenbecker, M. J., Adams, B., & Burnside, E. (Eds.). (2012). Fire detection and suppression systems (4th ed.). Stillwater, OK: Fire Protection Publications.
Potter Electric Signal Company, LLC (2010). Fire Alarm Systems Training Manual. Retrieved from https://www.pottersignal.com/training/manuals/8700055_FireTrainingManual.pdf.
NFPA 10: Standard for Portable Fire Extinguishers, 2015 Edition. In NFPA National Fire Codes Online. Retrieved from http://codesonline.nfpa.org.
NFPA 14: Standard for the Installation of Standpipe and Hose Systems, 2015 Edition. In NFPA National Fire Codes Online. Retrieved from http://codesonline.nfpa.org.
IFSTA (2013). Essential of Firefighting 6th Edition. Stillwater, OK: Fire Protection Publications.
Patrick Nicholson is the fire marshal for Kittitas County, Washington, and a 24-year fire service veteran. He has an A.S. in fire science from Columbia Southern University. He is a NAFI certified fire and explosion investigator and vehicle fire investigator.