Fire alarm sensing or signaling devices are the devices that inform the fire alarm control panel when there is any fire danger in its incipient stage. They are the devices that start the protection process and are mostly transducers that can compare their environmental condition to standard atmospheric conditions.
Due to their function, careful selection must have a reliable, flexible, and problem-free alarm system. The problem includes false alarm or failure to transmit signal promptly to the fire alarm control panel.
We have several types of fire alarm sensing devices in the industry, but the five commonly used are;
1- Heat Detectors
Heat detectors are the Fire alarm sensing devices designed to notify home occupants when the temperature is above the acceptable indoor condition. They are mostly used in areas susceptible to unusually high temperatures, such as kitchens, generator rooms, boilers, or places where heat change may surpass smoke. They are two types in the industry;
1- The Fixed Temperature heat detectors are the heat detectors, which has a constant temperature value for signaling the control panel. They are also called Static heat detectors and are commonly used in kitchen areas and boilers’ room.
2- The Rate of Rise Heat Detectors is the heat detectors that only signal the fire control panel when there is an abnormal or complete change in temperature. This detector type signals the control panel when they observe a sudden temperature change. They are commonly used in garages, loading bay, etc.
Heat Detectors have an individual coverage diameter of 5m and are spaced by a maximum of 10m apart while the maximum mounting height is 7.5m.
2- Smoke Detectors
Smoke detectors are the most common type of fire alarm sensing devices because smoke is the first product of any combustion. They are of various kinds, each responding to different types of smoke. This includes Optical, High Performance, Ionization, Photoelectric, or those designed to serve specific functions such as the Duct Smoke Detectors.
The Heat Enhance Carbon Monoxide Detectors are the most common types of smoke detectors use in the building industry because of their ability to detect smoldering fire.
Smoke detectors have an individual coverage diameter of 7.5m and are spaced by a maximum of 15m apart, while the maximum mounting height is 10m.
3- Multi-Sensor Detectors
Multi-sensor detectors are the type of sensors that can observe smoke and heat change simultaneously. They are designed to be a combination of smoke detectors and heat detectors. They are also common in the industry, but they are less being used in a residential project due to some other factors such as cost. They are commonly installed in critical areas such as the electrical room, Control room, IT room, etc.
Multi-sensor detectors share properties with smoke detectors by having an individual coverage diameter of 7.5m and can be spaced 14m apart, while the maximum mounting height is 10m.
4- Radiant Energy Fire Detectors
This type of detector uses sensitive infra-red sensors to sample the areas they are protecting. Although an unobstructed line of sight is required, they are the best to be used for critical spaces. We can’t wait for the smoke to be detected or areas with explosive or flammable liquids such as petrochemical projects, furnaces, and paper factories. An example is a Flame detector.
5- Beam Detectors
These detectors use high elevation buildings or projects such as warehouses, cathedrals, workshops, etc. This is because ordinary detectors’ view range may not reach the floor, mostly the source of all fire. A beam detector consists of two units, a Transmitter, which projects an infra-red light beam, and a Receiver that received a light beam and converts it to a signal.
Beam detectors operate based on the analogy that infra-red light will be unable to pass through fire smoke, and the receiver unit turns into its alarm mode when it’s unable to receive the signal from the transmitter.
The units can be placed at a maximum of 100m apart while the maximum space between two detectors is 15m.
6- Gas Detectors
Gas detectors are detectors that are sensitive to combustible toxic gases and oxygen depletion. They are mostly used in industrial plants, refineries, pharmaceutical, and manufacturing industries to detect gas leaks.
Further gas detector application includes facilities such as fumigation facilities, waste-water treatment facilities, aircraft, and shipbuilding facilities.