Fire alarm systems are essential for mitigating the severity of fires and the damage they cause by enabling rapid control of the fire by alerting all occupants of its presence. Therefore, detectors and alarms have been designed in various types and forms according to the nature of the sites and locations that require a fire alarm panel, fire alarm detectors, siren devices, and high-temperature-resistant wires and cables.
The primary purpose of fire alarm systems is to respond quickly to a fire by alerting an individual or group of individuals in the building, location, or emergency or fire station that a fire is in its early stages. The stages of a fire are divided into:
Stage 1: Incipient Stage: The fire has no smoke or odor, it is just starting to form and is small and unnoticed.
Stage 2: Smoke begins to form and the fire becomes visible.
Stage 3: Flames begin to appear and smoke rises, which is the stage at which the fire alarm is triggered.
Stage 4: The fire develops to its maximum intensity and spreads rapidly. It must be extinguished before it can continue during this stage.
Fire alarm systems rely on three methods:
Conventional System: This system only alarms in the area of the fire, and security personnel are responsible for locating the affected area.
Addressable System: This system carries numbers and names of the locations of the fire detectors connected to the main panel, so that the number and name of the area where the fire is occurring is displayed on the panel.
Automatic Fire Alarm and Extinguishing System: This system is installed on automatic extinguishing systems.
Types of Fire Alarm Systems
- Smoke detector: Used in corridors and rooms.
- Heat detector: Used in kitchens.
- Smoke and heat detector: Used in electrical rooms, air conditioning units, and places with machinery.
- Manual fire alarm break: Used in entrances and stairways.
- Gas detector:
- Visual alarm detector:
Components of Fire Alarm Systems
Fire alarm systems consist of:
- Control panel or main panel: A digital panel that receives signals from detectors installed in different locations and converts them into an audible and visual alarm for emergency exits.
- Fire alarm system detectors: These are detectors and sensors that are connected to the control panel to detect a fire and send a signal to the control panel, such as:
- Smoke detector: Activates when smoke rises from the site and sends a signal to the main panel.
- Heat detector: Activates when the temperature rises at the site, detecting any rise in temperature and sending a signal to the control panel.
- Glass break or manual release unit: In some cases, the system may be operated manually in the event of a fire by breaking the glass break and pressing the button inside, so that the control panel receives the alarm signal immediately and the alarm is activated to alert all workers that there is a fire.
- Gas detector: Activates when a gas leak is detected at the site, detecting the presence of any gas at the site and sending a signal to the control panel.
- Visual detectors:
- Power supply and charging unit:
- External connections: Both alarm panels are connected to the main alarm panel located in the security room.
- Alarms and sirens: These can operate efficiently up to a temperature of about 50°C and are installed outside the building at a height of about 3 meters and are not affected by weather conditions and are of the sealed type to prevent water or dust from entering them. They are also accompanied by sirens mounted outside the communications building with flashing lights that operate at the same time as the siren to provide visual confirmation of the hall from which the alarm is coming.
- Fire alarm system gas or liquid cylinders: These are cylindrical devices that contain a liquid or gaseous material that can react with the fire to extinguish or suppress the fire.
- Cylinder: A cylindrical metal box that stores certain materials to extinguish the burning fire.
Types of Fire Alarm Sensors (continued)
- Dual smoke and heat sensor: This type relies on both methods in operation and is used in places with dense fumes and smoke instead of a smoke sensor as it is more effective than it.
- Beam detector: This type is used in high-rise areas such as warehouses, cinemas, and theaters because ordinary sensors cannot sense the fire at these heights. This type of sensor consists of two parts, one for transmission and the other for reception, and it is installed at a height of 7 to 10 meters and is installed in places that exceed 6 meters in height.
Specifications of Fire Alarm Devices
There are a number of specifications and features that a fire alarm device must have:
- Detectors must be able to operate on a continuous voltage of 8 to 26 volts DC.
- To operate efficiently at temperatures up to 80°C.
- To operate efficiently in relative humidity conditions that may reach up to 95%.
- To be able to sense non-visible combustion gases.
- The detector must be resistant to moisture, dust, and rust and does not allow insects to enter it.
- The system must be able to give an alarm when one of the detectors is removed from its base.
Tips for Maintaining Fire Alarm Systems
Maintaining fire alarm systems is an assurance of early detection and control of fires before they cause material and human losses. They can be maintained through:
For sensor heads of all types:
- Heads must remain uncovered and not covered, and must be installed on ceilings and ensure that there is no paint on them so that they do not lose their sensitivity.
- It is necessary to install a protective circuit around it to protect it from possible shocks, provided that this protection does not affect the sensitivity of the heads.
- It is necessary to make sure on an ongoing basis that the alarm system is safe and sound and that the electrical resources feeding it are sufficient, by carrying out periodic maintenance on it by testing the system at regular intervals and informing all persons present inside the building of these tests. The devices must return to their state after the tests.
- During the maintenance and testing of fire alarm systems, this should include checking all system installations, as well as testing the batteries for powering the alarm system with the secondary power supply when the primary power is interrupted, and ensuring that they are working properly. The test results must be documented in a special register.
Maintenance of the main panel and ensuring that it operates efficiently in cases of:
- “Power failure to the panel, battery voltage drop, panel failure, circuit wire failure, removal of a detector from its base.”
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What to Consider When Installing Fire Alarm Systems
There are also some steps that must be considered when installing fire alarms, which also increase the lifespan of the systems and make them more effective and operate efficiently, namely:
Ceiling height: This is one of the most important considerations that affect the sensitivity of the alarm system. The system head and sensors are designed to sense smoke or heat or both when installed on the ceiling at a height not exceeding thirty feet (about ten meters). If the ceiling height exceeds this limit, the sensor may not be able to sense the fire in the appropriate stage to control it, or the alarm may not go off, which may cause some difficulties if the automatic system is to be used.
Air conditioning units: Air conditioning or ventilation units may affect the sensitivity of the alarm system and disable it, as these units may draw air laden with heat and smoke rising from the fire away from the exposed sensitive heads, thus not affecting the sensitivity of the detectors. Therefore, it is recommended that buildings equipped with air conditioning or ventilation units be equipped with smoke detector heads in the air passages to ensure that the fire is announced when smoke or heat cannot reach the sensitive heads on the ceilings.
Places containing valuables that are not easily flammable: Heat detector heads are not suitable in places containing delicate instruments and devices that are valuable and do not burn easily, as they may not result in a rise in temperature in the place, which leads to not sensing the fire, although any minor damage to these devices may cause losses. In such places, it is recommended to install smoke detector heads because they are more sensitive.
False alarms: The automatic system may give false alarms under certain conditions. These conditions vary depending on the type of detector head. For example, heat detector heads can cause a false alarm due to a rise in the temperature of the place due to the presence of heating devices or for manufacturing purposes or exposure to sunlight. This can be avoided by reducing the sensitivity of the heads so that they are not affected by the expected rise in temperature that may occur in the place.
The best fire alarm system companies
Companies that design fire alarm systems must be carefully chosen because they can cause significant losses. However, whatever companies or factories need from fire alarm systems, whether they are conventional, addressable, or the appropriate detector type for the place, FireTech Integrated Security Systems has all the systems.
FireTech provides all types of systems and components, from control panels to smoke and heat detectors, as well as the ability to install systems for various locations, from schools to airports.
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