CONVENTIONAL FIRE ALARM SYSTEMS
Conventional systems are hardware-based and use analog technology. These systems are made up of zones (“area/wide area zoning”) which are formed by using multiple devices, both initiating and notification devices connected to the main control panel.
Since, conventional systems are analog in nature, they use electrical currents to communicate with the control panel. Initiating and notification devices are designed to dramatically increase the current in the circuit (the amount of electricity flowing through the wires) any time the environmental conditions (heat or smoke) in the area of the sensor exceed a predetermined threshold. This change in the current is communicated to the control panel to trigger the alarm. Since the conventional system relies on individual circuits to communicate with the control panel, the information that the control panel can receive is limited to the number of devices it can support.
The information is also limited in the sense that it only tells the panel whether a device has been activated or removed, not which device or where.
In a Conventional Fire Alarm System, physical cabling is used to interconnect several call points and detectors, the signals from which are wired back to the main control unit. Single device or set of devices connected in a loop represent one individual “zones” (area/ wide-area zoning) & the incident area is indicated at the fire alarm control panel either with an indicator lamp, a text display or in some cases both.
ADDRESSABLE FIRE ALARM SYSTEMS (Intelligent/ Smart)
Instead of relying on changes in the electrical current running through a circuit in a conventional system, with an addressable system digital technology transfers information from the connected devices to the main control panel as binary code – combinations of ones and zeros.
The alarm signal starts as an analog signal created by variations in voltage within the signalling device based on changes in the coverage. In the new age addressable devices this analogue signal is converted in to a digital or binary signal using a digital signal converter or in built processors.
Depending on the device and the types of information it is designed to convey, an addressable device can transfer a wide variety of critical information to the control panel as opposed to the single triggering signal that conventional systems provide.
Because they use digital technology, addressable systems offer a much broader range in the types of information that the control panel can receive from the devices. While all addressable systems provide the location of every device on the system to the control panel, newer, “analog addressable” systems provide even more information, such as how much smoke or heat the detector is sensing. This information allows the control panel to make “intelligent” decisions such as when or when not to go into alarm mode.
The most important type of information that addressable systems transmit is exactly where the fire is occurring in a building (“Pointed/Focussed Zoning”). Because the exact location of each device in an addressable system is programmed in, fire-fighters know before they even arrive precisely where in the building the fire is occurring, which allows them to respond more quickly to a fire. With a conventional system, unless the area in which the system is protecting is a single room, the fire-fighters will have to spread out to locate the fire.
Intelligent Fire Panels, on the other hand, give every detector a uniquely identifiable address & they literally become a zone in themselves yet a much smaller, thus when a fire is detected, the main control panel tells you exactly which device is going off, to point out exact location on incident (Pointed or Focussed Zoning). Such pointed zoning is extremely useful in case of large and complex buildings or area.
One big advantage of intelligent type systems is that the data output of detector is sensitive to the local environment which is very useful to know when the device is approaching an alarm condition by integrating multiple type of information e.g. in case of a fire, thee multiple sensors can have information of intensity of heat, density of smoke, types of gases, occupancy level, illumination level etc. before raising the alarm. This “Pre-Alarm” can be signalled at the panel and can therefore be investigated to check if there is a real fire, or if it is caused by other signals, for example steam or dust from building work. This can avoid the inconvenience and expense of evacuating a building or calling out the fire brigade unnecessarily because of a nuisance alarm. The Pre-Alarm Threshold is typically set at 80% of the alarm threshold.
Conventional Vs. Addressable Fire Alarm Systems
Conventional fire alarm systems have indeed been around a long time and have proven their reliability & credibility yet in today’s digital world, people often think of analog devices or systems as old fashioned or with out-dated technology. Many businesses today still use them; and, while newer technologies now exist, conventional systems still remains a good option in some settings.
Conventional systems are highly reliable, cost-effective, and affordable for small buildings where just one or two zones could cover the entire area. However, more and more small businesses are beginning to consider addressable systems when it comes time to replace their systems for additional benefits that the newer technology provides.
The key to selecting the right one is to look beyond the initial costs when evaluating the lifetime value of the system. There are many associated factors with each type of system that may make one a better choice than the other.
A closer look at some of the key differences between conventional and addressable systems can be summarised as below:
a. False Alarms: False alarms are always an important consideration as they are expensive for fire departments majorly in terms wastes cost, time & efforts. False alarms are far more common with conventional systems. In contrast, addressable devices are always getting monitored by alarm panel for their sensitivity preventing the occurrence of false alarms. The sensitivity of the sensors in addressable devices can also be adjusted. Also, Addressable devices provide “drift compensation” – the ability to distinguish between subtle changes in the level of smoke detection that occur over time due to contamination, like dust, and rapid changes resulting from a real fire.
b. Safety Considerations: Without a doubt, addressable systems provide a greater level of fire safety because they allow fire-fighters to respond more quickly and effectively by pinpointing the exact location of a fire in a building.
c. Reliability: An addressable system is generally more reliable than a conventional system mainly due to how the different systems are wired. With a conventional system, if a device’s wire is damaged or severed, its signal and the signal of other devices down the line cannot be transmitted to the control panel. With an addressable system, both ends of the wire connect to the control panel. Therefore, if one end becomes damaged or severed, signals can still reach the control panel through the other end of the loop. In addressable systems, a device can be removed or disabled and it will not affect the other devices in the loop.
d. Scalability: Addressable systems provide a great deal of flexibility in comparison to conventional systems. While the number of devices either system can accommodate is determinant on the manufacturer of the alarm panels, every type of device added to a conventional system requires a new circuit. Because they require less wire, an addressable alarm control panel can accommodate far more devices than a conventional system. They can have anywhere from one to 30 loops, commonly referred to as a signalling line circuit (SLC), each of which can monitor and control several hundred devices.
e. Life Cycle Cost: The equipment required for conventional systems usually comes with a much lower price tag than addressable systems, which is why conventional systems are still a popular choice for small businesses. However, it is wise to look beyond the initial costs. Even for small buildings, the lower initial costs to purchase the equipment needed for a conventional system are often offset by higher installation costs. Remember that conventional systems require a single circuit for each zone, one which can lead to much more complex wiring than an addressable system in which all the devices are wired into a single loop. This increase in complexity not only drives up the cost of installation but also introduces a greater risk of human error.
While both types of systems require regular inspections and testing, trouble-shooting and maintenance are easier and less expensive with addressable systems. With independently wired zones in a conventional system, each device must be checked separately to find the problematic device. Addressable devices can send maintenance alerts and trouble signals to the control panel to make finding problematic devices and getting them repaired or replaced much faster.