The 21st century has brought new challenges and newly emerging hazards that have led to a demand for ever-increasing precision in fire-detection initializing devices as well as notification systems. New technologies, such as the Internet of Things and ever-increasing interdisciplinary system integration, are utilized in installations to reduce detection and response times that lead to safer and faster evacuation.
One major factor for recent advances in fire detection is the ever-wider use and acceptance of new fire-detector technologies.
Aspiration smoke detectors (ASD) have been one of the fastest-growing detector types, a fact that is evident in the expansion of the related paragraphs in Chapter 17 of NFPA 72 as well as their recent introduction in European Norm (EN) 54 part 14 guidelines. Aspiration smoke sensors in the market are based on two types of technologies:
- Point-based solution, with the system consisting of enclosed smoke sensors with a fan system that continuously draws air samples
- Light-scattering-based solution, in which the system draws air into a laser or LED chamber to detect threats.
Aspiration sensors offer two advantages in comparison to point-type smoke detectors: much higher accuracy and the ability to detect fire in large open areas, where stratification and smoke dilution is likely to occur. These advantages have led to aspirating sensors being widely used in two types of installations that define the second decade of the 21st century: large data centers and logistic hubs.
The challenge in the adoption of these types of sensors in a wider range of installations is two-fold. First, there is a lack of awareness of their benefits among end-users that, with the addition of greater initial installation costs than regular point sensors, tend to shy away from new and more expensive solutions and, second, there is a reluctance of system designers and installers to promote aspirating sensors due to the complexity of the pipe network that this type of sensor requires.
Another emergent type of fire-detection technology on the rise is linear heat detection. Linear heat sensors just recently made their appearance in Europe, with the introduction of the European Norm (EN) part 28. Furthermore, NFPA 72 offers the provision of utilizing linear heat sensors in installations with very high ceilings, with the sensors selected on performance-based criteria.
Linear heat sensors detect temperature changes in the environment and, depending on the type of sensor used, are categorized into three groups:
- Cable-based solutions, in which a specialized cable, covered with a coating that melts in certain temperatures is used
- Optic-fibre solutions, which are utilized in long straight installations such as tunnels, and are based on Raman backscattering of laser light along with an optic fibre
- Air-pressure-based solutions, which are based on the principle that as the ambient temperature increases in the event of a fire, the volume of heated air also expands along an enclosed air-filled tube.
Linear heat sensors, on their part, have different advantages based on the technology they utilize. Cable-based solutions tend to be robust, easy to install, and widely used in the US but lose their efficiency and become more cumbersome as the ceiling heights rise. The recently introduced air-pressure-based solutions can be utilized in higher ceilings and harsher environments, such as cold-storage and installations that require HACCP guidelines, allowing the use of linear heat detectors in a wider variety of cases. Furthermore, air pressure-based solutions are also extremely sensitive and resettable, surmounting the two main drawbacks of linear heat sensors. As with aspirating sensors, the greatest challenge to the wider introduction of linear heat is both a lack of awareness of their benefits and a reluctance from the designers and installers to propose any solution that utilizes pipe systems.
An emergent fire-detection technology that differentiates over traditional smoke- or temperature-based detection systems is Video Image Detection (VID). The widespread rise of video surveillance, especially after 9/11, and the recent advances of real-time video processing have enabled the development of VID for fire. The major difference between VID systems over traditional fire-detection systems is that they eschews the detector approach to fire detection and are essentially advanced algorithms that utilize video cameras to detect smoke or fire presence.
Initially, the VID system utilizes a central controller with a different number of video cameras that provide the image feed for the system. Relay outputs provide alarm and fault signals to fire-detection control panels and could provide video output to monitors. Recent advances in the miniaturization of components have led to the development of stand-alone VIDs that can execute both video processing and algorithm execution on a single, spot-type detector. Integration of these spot VID detectors can be on both closed-circuit systems as well as on fire-detection panels.
The VID systems are recognized on NFPA 72 but on a performance-based design. As such, the system must be inspected, tested and maintained based on the manufacturer’s recommendations, but flame VID detectors are classified as radiant-energy-sensing fire detectors, the same as IR-based flame detectors. In Europe, this type of detectors is not yet recognized by European Norms (Standards).
Video Image Detectors offer the initial advantage that can utilize already present closed-circuit systems hardware and wiring. Also, they can protect a wide area and installations with high ceilings and fast response times, as they do not require the smoke to migrate to the detector. The ability of the VID system to disregard nuisances depends on the robustness of the algorithm used as well as the initial commissioning of the system.
Apart from advancements in single detector technologies, fire-detection systems also implement recent trends in Internet of Things and wireless connectivity. Wireless detectors have been recognized by NFPA 72 as far back as 1987 as low-power radio systems, but two recent advancements have led to the development of wireless detectors for domestic applications. One is the abolishment of NFPA 720 for CO detectors and its introduction to NFPA 72, and the other is the rapid implementation of Internet of Things for smart-home applications.
The introduction of CO detection to the general fire-detection design has led to the development of stand-alone wireless detectors for home use that can detect both CO and optical smoke. This type of combination detectors offers increased sensitivity, as they can also detect the CO that is a by-product of combustion, as well as a second level of protection against malfunctioning fireplaces or stoves. The recent trend in residential fire detection is a cluster of stand-alone combination CO/optical smoke detectors, interconnected via wireless Wi-Fi to the smart home network. This trend tends to abolish the cumbersome and unintuitive fire-detection panels from homes and replace them with smartphone applications as well as lowering installation and maintenance costs.
The application of Internet of Things (IoT) connectivity on fire-detection systems was not limited only to wireless stand-alone detectors. New fire-detection panels offer a wide variety of connectivity and notification options, from massive email lists to specific application control, but IoT technology also offers a new level of system integration. Newer building installations have management systems (BMS) that incorporate all their different systems, from HVAC and plumbing to power distribution and networks. Introducing the fire-detection system to the central BMS is the next logical step, as the fire-detection panel can issue commands to other interconnected systems and prevent further deterioration of the emergency or aid in the orderly evacuation of the building. Furthermore, complete integration of fire-detection systems to building management systems and the use of prescriptive maintenance, achieved by monitoring a large number of variables from the connected detectors, offer lower maintenance costs, greater accuracy and sensitivity of the system as well as a prediction of mean time between faults for the system, with the aid of machine-learning algorithms.
The next step of emergency system integration is the complete cooperation of fire-detection, emergency lighting and voice-evacuation systems in a complete system that reduces building evacuation times and reacts in real time to changes in the emergency. Dynamic escape-route emergency-lighting systems change the type of the pictograms according to the situation, preventing occupants from following paths that are blocked. Furthermore, high-fidelity voice-announcement systems can intuitively guide the occupants and also can provide a means for the first-responder teams to issue further commands and instructions via integrated firefighter telephones. These types of systems are not only effective in case of fire but can also provide valuable alarms and instructions in other situations, such as chemical spill, intruder, or extreme weather phenomena.
Accidents are a part of everyday life and, even with the best of technologies, they cannot be eliminated. But emergent solutions and connected products can aid us in gathering crucial alerts early and correctly, reducing reaction and evacuation times. Designers and end users should embrace these solutions but should also adhere rigidly to appropriate regulations and policies to provide a coherent plan, with the proper implementation for each situation. Only then can the end goal, the protection of human life and property, be achieved.
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About the Author
Thanasis Eleftheroudis is a Dipl. Electrical Engineer and Computer Engineer with Olympia Electronics.
