Most victims of fire succumb to the smoke and toxic gases and not to burns. Fire produces poisonous gases that can spread rapidly and far from the fire itself to claim victims who are asleep and not even aware of the fire. Even if residents awaken, the effects of exposure to these gases can cloud their thinking and slow their reactions so that they cannot make their escape. This is why it is so crucial for you to have sufficient warning so that you can escape before your ability to think and move is impaired. In addition, more than half of fatal fires in homes occur when people are asleep.

Fire alarm system is to provide an early warning of fire so that people can be evacuated & immediate action can be taken to stop or eliminate of the fire effect as soon as possible. Alarm can be triggered by using detectors or by manual call point (Remotely). To alert/evacuate the occupants siren are used. With the Intelligent Building of the rapid development of technology applications, commercial fire alarm market demand growth, the key is to use the bus system intelligent distributed computer system fire alarm system, although installation in the system much easier than in the past, but still cannot meet the modern needs, the installation costs of equipment costs about 33% ~ 70. The suggested technique in Fire alarm system used the addressable detectors units besides using the wireless connection between the detector in zones as a slave units and the main control unit as the master unit. The system shall include a control panel, alarm initiating devices, notification appliances, and the accessory equipment necessary for a complete functioning fire alarm system. In the wireless fire alarm, individual units are powered by primary & secondary batteries for the communication. The fire alarm system can also be integrated with AC supply, access control, fire fighting systems, Building Management System (BMS)…..etc. To indicate the area where fire exist fire indicating/fire alarm panels are used. So far, cables were used to integrate all the device of fire alarm systems, these cables carried the power & communication. When we have unique address; therefore all these devices can be easily identifiable, controllable & networkable as required by the end users.

Alarm Systems
the most basic alarm system is designed to only be initiated manually. This is a local warning system similar to the type installed in schools or theaters, and the signal alerts occupants of the need to evacuate the premises. While alarm standards have traditionally called this type a local system. A wide variety of optional features are available to expand the capabilities of an alarm system. Automatic fire detection devices may be added, allowing the system to sense the presence of a fire and to initiate a signal.

Fire Alarm System Structure Design
There are three main designs for the fire alarm systems;
§ Conventional Analogue Fire alarm system,
§ Addressable Analogue Fire alarm system,
§ Wireless Fire alarm system.

 Conventional System
The main bone of this system is the Circuit board. The single circuit board contains power supply, control, and initiating and notification circuitry. Designated outputs occur when initiating signals are received. This system is not expensive but not addressed beside it is a wired System. The conventional fire alarm systems have many features such as;
§ Two state Detector (Normal state, alarm state),
§ Two wire connection,
§ Separate indicator in the main fire alarm panel,
§ Smoke detector, and Heat Detector,
§ Manual Break Glass can share the same circuit as
detectors,
§ Removal of any detector shall not prevent from
the operating of any break glass.

Addressable System “Multiplexed”
Each device (detector, pull station…etc.) has a unique number assigned to call the address for reporting alarms and troubles. Addressable devices transmit an electronic message back to the Control unit representing their state (Normal, Alarm, Trouble) when polled by the Control Unit. The addressable systems have many features such as Addressable detector, call points, signals which is individually identified by the control panel.
§ Addressable detectors shall be connected via two wire connection such that the connection of the both wire to form a loop in order to provide circuit integrity.
§ Addressable detector is addressed through soft addressing or dip switch.
§ Multiplex communication technique allows each detector to independently signal it status back to the control panel.
§ Addressable system can also handle output device on the zone circuit, where the address massage can be command instruction to an output device (on/Off) Example: Sounder Module, Switching On/Off Relays.
§ Interface module is a device that is used to interface the conventional alarm system and the addressable system.
Addressable system (a) Circuit (b) Structure
the sensors give an analog output signal representing the value of the sense phenomenon. The output of an analogue addressable detector is variable and it is proportional representation of the sense effect of fire, smoke and flame. Transition of this output from a detector is usually in a form of analog current to the control panel that tells the panel what condition of the room being sense monitored. In order for an analog addressable system to raise alarm, the analog value output by the detector must be in the alarm condition (above the alarm threshold) for a period equal to time taken to complete three successive address sequences (6 sec).
The addressable system has the advantages that it is Addressed system, Easy Install, and accurate system. But historically, addressable systems have tended to be complicated to configure.

Wireless Fire Alarm System (Suggested technique)
As in recent years in human micro-electromechanical systems, wireless communications, digital electronics has made great achievements, making the development of low-cost, low power consumption, small size, and short-range multisensory communication possible. Wireless sensor network and artificial intelligence integration can greatly enhance the reliability of fire alarm system.

This system consist of a central control panel to which smoke alarms and heat detectors are connected, along with bells or horns that are activated when the system triggers an alarm. Other sensors associated with the burglary functions connect to
doors and windows or monitor rooms for motion or body heat. The control panel operates from wall power but also usually contains an emergency battery which can operate the system for about 24 hours during a power outage. The basic requirements for the number and locations of alarms are exactly the same as with the self-contained alarms discussed previously. The difference is that fire alarm system gives more flexibility to locate additional alarms and additional bells or horns (or flashing lights, should a person in the building be hearing impaired). The sensors give a digital output signal representing the value of the sense phenomenon. The output of a digital conventional detector is variable and it is proportional representation of the sense effect of fire, smoke and flame. Transition of this output from a detector is in a form of digital current to the control panel that tells the panel what condition of the room being sense /monitored.

Wireless importance
RF wireless technology is a short distance, low-complexity, low-power, low data rate, low-cost two-way wireless communication technologies, mainly suitable for the field of automatic control and remote control can be embedded into various devices, at the same time support the geo-positioning function. With increasing distance communication, equipment complexity, power consumption and system costs are on the rise. Compared with the existing wireless communication technologies, RF wireless technology will be the lowest power consumption and cost of technology. But low data rate and communication range of the smaller features of RF wireless technology also determines the flow of data is suitable for carrying smaller business.
Generally speaking, there is an importance for the wireless technology;
§ Ability to interconnect without wires.
§ Install in minutes, anywhere in the homeless cost than re-wiring.
§ Mobility & Adaptability.

Conclusion
The primary advantage of a home fire alarm system is increased reliability and the ability to place alarms and bells exactly where needed. However, the reason most people have them is that they wanted a burglar alarm system and the cost of adding fire alarm features to a residential burglary system is relatively small. Another advantage is that they are the only way to obtain remote monitoring services. This
becomes important in cases where family members may not be capable of escaping from a fire without assistance. For example, if you have an older or physically impaired person in your home and a fire started when no one was home to assist that person,
alarms alone might not be enough to assure their safety. Fire wireless sensor platform of hardware and software design for the entire system development and application is essential, as the bottom of the whole system support to the miniaturization of its inevitable, highly integrated, network-based, energy-saving and intelligent direction, nearly few years, with the declining cost of computer and microprocessor to reduce the size, development and construction of intelligent wireless fire alarm system will have broad application prospects. Engineering test results fully demonstrated the technical feasibility and the effectiveness of the realization. Fire alarm systems that provide remote monitoring services can also be used to provide medical alert services.

Finally, we can say by applying the suggested technique in Fire Alarm wireless Intelligent system that this system has advantages of Low cost System, Addressable system, Integrated networkability, Conventional detector used” lower wiring costs”. Also it has little disadvantages of System will be failed if the slaves’ unit network has a
failure.

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