Wireless Fire Alarm System Design
Wireless Versus Other Systems
When discussing how wireless fire detection systems work, it helps to understand other types of fire alarm systems including:
- Conventional fire alarm systems
- Two-wire fire alarm systems
- Analog-addressable fire alarm systems
Conventional wired fire alarm systems, also known as four-wire systems, have been used in the full range of residential, commercial, and industrial properties for decades. Less expensive than other types, they work with detection zones that have detectors and call points that are hard-wired to the control panel using dedicated circuits. Separate two-core cable is needed for each audible alarm (a sounder or bell) because these are wired to different loops.
When a detector in a conventional system is activated, the control panel identifies the circuit where the device was triggered so that the area can be manually searched. This is the system that was most common when elevator recall was first introduced.
Two-wire systems are based on the standard conventional type of system, but the alarm devices, call points, and detectors used for each of the zones are wired on the same set of two-core cables that link back to the control panel. This enables designers to ensure that a single-circuit is used in each zone to both detect and power audio sounders or sirens. Although they cost more than conventional systems, two-wire systems are, ironically, less expensive to install, and they are considerably more flexible in the way they work. Additional functionality includes the recognition of fault conditions and detector recognition.
While conventional fire alarm systems provide information about specific zones or circuits, analog-addressable fire alarm systems provide details to the fire control panel that relate to individual detectors, each of which has its own unique address. This means that it is easy to see exactly where the smoke, heat, fire, or fault is located. The different initiating devices are wire-in loops in the building which also requires less cabling than conventional systems.
Often referred to as “intelligent” fire alarm systems, analog-addressable systems are a lot more expensive and complicated in terms of installation and operation than the other two types mentioned above. However, they offer increased flexibility, a greater speed of identification, a more expansive scope of control, and are therefore commonly designed for large commercial premises.
Increasingly sophisticated and reliable, wireless fire alarm systems have multi-frequency links that eliminate signal blocking and maintain a higher margin of signal strength. Fire alarm panels are designed to communicate with detectors and sensors using radio signals.
More expensive than other types of fire alarm system, they are considerably more flexible than any of the wired systems. They are also less susceptible to fire than wired installations which are in danger of circuit damage that could compromise the entire system.
Research indicates that by 2024 the wireless fire detection market will exceed US$500 million. Indications are that its incredible growth may be attributed to a range of factors including the ease of installation, the fact that they are more aesthetically pleasing than wired systems, and because they can be used in properties where wiring is not permitted.
Wired systems rely on slotting and through-wall ducts that not only look ugly but can damage buildings if not done with the appropriate skills and care. Because wireless fire alarm systems don’t need any through-wall ducts there is no danger of damage. They are also adaptable to the change of use and function of buildings. But they must be correctly designed to meet all the strict Fire Department and code requirements.
The fact that intelligent, addressable fire alarm panels are being used more and more is a key driver for wireless sensor technology. Improved visual and auditory confirmation of emergency situation and increased elimination of false alarms (or alerts) have also had an impact on the market, effectively helping wireless designs gain momentum.
Long Range Wireless Technology
Heralded as the DNA of the Internet of Things (IoT), long range (LoRa) low power, wide-area network technology offers low-energy consumption and a much longer range than ordinary Wi-Fi – about a mile in typically crowded urban settings and ten times the range in more rural locations. Low power, wide area networks (LPWAN) also have a much lower data rate than standard Wi-Fi because data transmission needs are low.
LPWAN technology connects sensors to the Cloud, which means all the data required to run fire alarm systems is stored on the internet rather than on local computers. This enables real-time communication of analytics and data that can be used to improve productivity and efficiency.
While LoRa is a proprietary system made by Semtech, if it takes off the way they think it will, it could become the new wireless way of things, including wireless fire alarm systems.
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