Fire is one of the deadliest risks that all homeowners and businesses face, which is why having a fire alarm system is of the utmost importance. Fire alarm systems can save lives and minimize the destruction of property. They are designed to provide an early warning of the threat so that we can take action to protect ourselves and the public before the situation gets out of hand. Even if it becomes too late to stop the fire, a fire alarm system may be able to provide enough time for occupants to get out of the building.
Most fire detection and alarm systems operate under the same basic principle: if a fire is detected, then an alarm is triggered. An example would be a smoke detector sending a signal to the fire alarm control unit when there is a presence of smoke, which would initiate notifications to the occupants to evacuate.
The basic components of a fire alarm system are fire detectors, notification devices, a power supply, and a fire alarm control panel:
Fire Detector - detects the presence of fire early in its development
Alarm System - notifies the building occupants through strobe lights, speakers, bells, horns, etc.; may be integrated with a mass notification system or emergency communication system
Fire Alarm Control Panel - is the brain of the system, which serves as the central hub for all the detector signals and provides a status indication to users; it can also communicate the alarm situation to authorities and execute emergency control functions such as door closers and elevator recall
Power Supply - provides reliable power so the system remains operational in case of a power interruption
Fire Suppression - some systems are equipped with fire suppression devices, which subdues the fire before it has the chance to spread
Different Types of Fire Alarm Detectors
There is a wide array of fire detectors available, ranging from manually operated break glass units to intelligent smoke detectors with onboard computers. They detect signs of a fire, such as heat and smoke:
- Heat Detectors
Heat detectors either work on a fixed temperature basis, where the alarm is triggered if the temperature exceeds a certain threshold, or they can work based on the rate of change in temperature.
- Smoke Detectors
There are three basic types of smoke detectors:
Ionization Smoke Alarms: Ionization smoke alarms contain a small amount of radioactive material between two electrically charged plates which ionizes the air and causes a current to flow between the plates. When smoke enters the chamber, it disrupts the flow of ions, which then reduces the flow of current, thus activating the alarm.
Light Scattering Smoke Alarms: Light scattering smoke alarms operate on the Tyndall effect. The alarm is triggered when light from a light source within the detector is scattered by smoke entering the chamber, hitting the photocell inside.
Light Obscuring Smoke Alarms: in light obscuring smoke alarms, the alarm is triggered when smoke interferes with the light beam between a light source and a photocell within the detector. The photocell measures the amount of light it receives and initiates the alarm if it gets obscured by smoke.
- Carbon Monoxide Detectors
A CO fire detector senses the level of carbon monoxide in the air, which is a poisonous gas produced by combustion. Carbon monoxide detectors used in fire alarm systems are different and more sensitive than household carbon monoxide detectors, which are used to detect incomplete combustions in appliances such as gas stoves and boilers.
- Multi-sensor Detectors
A multi-sensor detector detects more than one fire phenomenon (such as heat and smoke). It combines inputs from multiple sensors and processes them using an algorithm built into its circuitry.
- Manual Call Points
Unlike the other fire detectors listed above, a manual call point is a device that enables personnel to manually raise the alarm in case of fire. Examples of manual call points include pull stations and break glass call points.
Different Types of Fire Alarm Systems
Fire alarm systems can be broadly categorized into three groups.
- Conventional Fire Alarm System
In a conventional fire alarm system, physical cabling is used to connect several call points and detectors. All detectors are wired back to the fire panel, which is also connected to sounder circuits that control bells, electronic sounders, and other audible fire alarm devices.
Call points and detectors are arranged in “zones” to help the fire department or the building management to locate the fire. Each zone is indicated at the fire alarm control panel with an indicator light, which would light up when a detector within the zone is triggered. The more a building is divided into zones, the more accurate locating the alarm trigger will be.
- Addressable Intelligent Fire Alarm System
In addressable intelligent systems, each detector is given a set address. The control panel can then determine exactly which detector or call point has initiated the alarm.
Each detector is also considered to be “intelligent” since it has its own onboard computer that can evaluate the environment around it and communicate to the control panel whether there is a fire, a fault, or if the detector head needs cleaning. This helps prevent the occurrence of false alarms. In conventional systems, detectors are not considered intelligent as they can only provide output for the detected phenomena.
- Wireless Fire Alarm System
Wireless fire alarm systems use radio communications to connect the sensors to the control panel, with no need for cabling between the components.
The main advantage of wireless fire alarms is that they can be installed very easily. The entire system is portable and can be moved as required.
It is important that a thorough assessment is undertaken before a fire detection and alarm system is designed or purchased. In the United States, fire alarm systems are regulated by the National Fire Protection Association (NFPA). The NFPA has over 300 codes and standards intended to minimize the possibility and effects of fire.
It is crucial to partner with a professional security integrator that specializes in fire protection, such as Absco Solutions. Absco Solutions can inspect your building, pinpoint compliance issues, recommend improvements, and perform the changes needed to bring the building up to the local code requirements or to ensure compliance from day one for new construction.
Give us a call at (425) 771-1166 or send us an email at email@example.com for more information.