What is a Fire Alarm System?
Fire Alarm Systems are designed to alert us to an emergency so that we can take action to protect ourselves, staff and the general public.
Fire alarms are found in Offices, Factories, and public buildings, they are a part of our everyday routine but are often overlooked until there is an emergency at which point, they might just save our lives.
Whatever the method of detection is, if the alarm is triggered, sounders will operate to warn people in the building that there may be a fire and to evacuate.
The fire alarm system may also incorporate a remote signal system which could then alert the fire brigade via a central station.
How Do Fire Alarm Systems Work?
A fire alarm system’s chief purpose is to detect fires and quickly notify both the occupants of the building and emergency services from a centrally controlled and monitored location. These systems also monitor themselves, identifying the location and origin of the alarms and sensing problems with connections and wiring that might prevent the system from working properly. Essentially, fire detection systems have four primary functions.
- Detection
- Alerts
- Monitoring
- Controlling
These highly advanced systems use a network of appliances, devices, and control panels to perform these four functions.
Components of an Alarm System
A fire alarm system consists of many components, including:
- Fire Alarm Control Panel
- Initiation Devices
- Pull Stations.
- Smoke Detectors
- Duct Detectors
- Heat Detectors
- Beam Detectors
- Air Aspirating or Air Sampling Smoke Detectors
- Water Flow Switches
- Tamper Switches
- Notification Devices
- Audible Devices
- Strobes
- Strobes/Horns
- Dialers Or Communicators
- NAC Power Supplies
Fire Alarm Control Panel
The fire alarm control panel, commonly abbreviated as FACU, is the system’s “brain.” It receives messages from the initiating devices, also known as inputs, and performs the following functions.
- Turning on notifications: Upon receiving signals from the inputs, the FACU will turn on the necessary notification devices, also known as outputs. It alerts people in the vicinity that an issue has occurred.
- Elevator recall: The FACU also recalls elevators, which eliminates the possibility of an elevator delivering people to a flame- or smoke-filled area.
- HVAC system shutdown: If they detect smoke in an air duct, many fire alarm systems will shut the air handling unit down, thus preventing smoke from spreading to other parts of the building.
- Notifying alarm monitoring center: The FACU will also alert a remote alarm monitoring station, which, in turn, will notify emergency services.
Minimizing False Alarms
A poorly designed or installed fire alarm system that does not get routine maintenance, testing and inspection will likely go off even when there is no genuine danger. Frequent false alarms will cause people to take them less seriously. When hearing a fire alarm, many people assume it is no cause for concern unless they also smell smoke or see flames.
To minimize the incidence of false alarms, the fire alarm industry has pushed for proper system design, installation, testing, maintenance, and inspection.
Types of Fire Alarm Panels
A fire alarm panel can be one of two types.
- Addressable: Addressable panels monitor all alarm components individually. Each device comes with a distinct, separate address, which allows the panel to know their status, such as whether it is functioning normally, in alarm or in trouble. For instance, addressable systems allow those working at a hotel’s front desk to know the exact location of the event by looking at the alarm panel display.
- Non-addressable: This type of system puts all initiating devices in zones, meaning users physically must check each device in that zone to find the one in alarm. For instance, if you have a non-addressable system and the alarm goes off, it will tell you something like “Alarm Zone 3, Fourth Floor.”
Most property owners and managers prefer addressable systems, as they let you know the specific location of the alarm and assess the situation much more quickly. Some fire alarm panels can also notify remote alarm monitoring stations, which can then contact emergency services.
The Three States of a Fire Alarm System
Fire alarm panels continuously monitor and indicate the state of the fire alarm system. For most systems, there are three possible states.
- Normal: “Normal” means that all appliances, devices, circuitry, and wiring are functioning correctly and that there are no active alarms.
- Alarm: This status indicates an active alarm.
- Trouble: If an open or short wiring develops in the circuits that connect the initiating devices and the fire alarm panel, or if the system’s phone line connection is not working, the system will go into a “trouble” state, which the control panel will display.
Initiation Devices
Initiation devices initiate alarms, and, just like alarm panels, they can be either addressable or non-addressable. Some initiation devices, like water flow switches, are traditionally non-addressable, but connect with addressable modules. The switches can have specific addresses that let them communicate with addressable systems.
There are many types of initiation devices. In addition to water flow switches, initiation devices can also be:
- Pull Stations
- Duct Detectors
- Smoke Detectors
- Beam Detectors
- Heat Detectors
- Tamper Switches
- Air Aspirating Detectors
Pull Stations
A pull station is probably the fire alarm system component you are most familiar with. It is a manually operated device that initiates an alarm signal when someone pulls its handle. While smoke may take a few minutes to reach a smoke detector, you can activate a pull station within just a few seconds of a fire or other emergency, which allows for a quicker evacuation and faster reaction times. Pull stations are available in various sizes and shapes and can come with protective covers upon request.
Smoke Detectors
A smoke detector is a device that initiates an alarm signal when it senses smoke. There are two classifications of these devices, depending on the type of sensor they use to detect smoke particles.
- Ionization Detectors: These detectors contain tiny traces of radioactive material between two electrically charged plates. Ions flow between these two charged plates, but smoke particles disrupt this. If this happens, the smoke detector goes off.
- Photoelectric Detectors: Photoelectric detectors emit LED light beams in their detection chamber. When smoke particles come into this chamber, they scatter the beam of light, deflecting part of it on the detector’s photoelectric sensor. When the sensor detects this light, the alarm goes off.
Duct Detectors
Duct detectors are smoke detectors installed in air conditioning and heating ducts. They shut air handling units down, preventing smoke from traveling all over the building via the air ducts.
Heat Detectors
Heat detectors are fire detection devices equipped with sensors that respond to heat. Two main kinds of heat detectors are available.
Types of Heat Detectors
- Rate-Of-Rise Heat Detectors: This type of heat detector will respond if the temperature increases at a rate that exceeds a specified value.
- Fixed Temperature Heat Detectors: Fixed temperature heat detectors will respond when their operating elements reach or exceed a predetermined temperature. There are two types of fixed temperature detectors: linear detectors, which monitor the temperature throughout an area, and spot detectors, which monitor the temperature in one specific location.
Beam Detectors
This kind of smoke detector projects a beam of light across the area it is protecting. If smoke crosses the path of the beam, the detector will respond.
Air Aspirating or Air Sampling Smoke Detectors
This type of detector uses tubes to deliver air or smoke to a central detector equipped with a sensor that can detect minute changes to the air’s chemical composition. These detectors are usually highly sensitive.
Water Flow Switches
Water flow switches use paddles located inside water-filled piping that will respond if water flows. On sprinkler systems, their design allows them to work if water is flowing from only one sprinkler.
Tamper Switches
A tamper switch is a supervisory initiating device that operates if someone moves its valve from its regular position.
Notification Devices
These devices send a visual or audible notification to alert a building’s occupants to evacuate.
Audible Devices
Audible devices include sirens, bells, and horns.
Strobes
Strobes send notifications by flashing a light.
Strobes/Horns
These devices send notifications by flashing a light and blaring a siren to alert people to respond.
Dialers or Communicators
Some fire alarm systems have internal or external dialers used to contact monitoring centers or alarm receiving stations. Communicators can use radio signals, phone lines or an internet connection to maintain contact. Panels may have built-in dialers or communicators.
NAC Power Supplies
Today’s systems require many notification devices, which need extra power supplies, known as notification power supplies, or NAC power supplies. You can find these by the main panel or distributed around the building as needed.
Find Out More
To learn more about getting a fire alarm installed for your home or business, you can contact us here at Hubtech Limited and schedule a consultation in order for us to cater to your every need. Check out our Shop for more information and equipment
