1.1 Introduction
An automatic fire alarm system is designed to detect the unwanted presence of fire by monitoring environmental changes associated with combustion. In general, a fire alarm system is classified as either automatically actuated, manually actuated, or both. Automatic fire alarm systems are intended to notify the building occupants to evacuate in the event of a fire or other emergency, report the event to an off-premises location in order to summon emergency services, and to prepare the structure and associated systems to control the spread of fire and smoke.
In modern society, it is impossible to imagine house or building without a fire accident detector. Modern houses require a continuous installation of fire detector. Not only industry, but also in the household. Take the case of a duplex that experience a fire accident without a detector that means everything in that building will get burnt even human beings. But in a case whereby fire alarm is installed that means everyone in that building will be alerted and also fire security bodies will also be informed for quick security action. The same thing can also happen to our offices and industries. In order to notify residence of any building in the presence of fire accident, a fire alarm system is used. As a prelude to other parts of this study, this chapter will discuss the background upon which this study was initiated, the statement of problems that led to this study, the Aim and Objectives of the study. Others are Significance of the study, Scope of work, Limitations of the Study and Definition of technical terms.
1.2 Background of Study
In 1902, an electrical engineer from England, George Andrew Darby has patented the electrical Heat-Indicator and Fire Alarm (EPA, 2021). This system operated by indicating an increase temperature above the safe limit in the room where it was fixed. Before scientists knew how to capture ionizing molecules in a small enclosed space, they actually used an open and close electrical system along with a wedge of butter to detect fires and heat. It consists of two plates or electrical circuits with a wedge of butter between them. When the heat of the room became overwhelming and the temperature is over the safe limit, the butter would melt. Both circuits collapse onto one another and then initiating the alarm. The first battery-operated home smoke detector was patented in 1969 by two Americans, Randolph Smith and Kenneth House.
For longer than recorded history, fire has been a source of comfort and catastrophe for the human race Fire is fast and self-sustaining oxidation process accompanied by the evolution of heat and light in varying intensities. In order to detect the presence of the smoke, smoke detection system is created. Every single electronic device in the building may have possibility to produce ignition whether through short circuit or any other ways. Even the charging mobile phone might contribute to the flame. Thus, awareness and consciousness of the importance of smoke detection system must be planted on people mind.
Fire is the major cause of accidents claiming valuable lives and property. The chemical reaction between carbon-based materials in presence of oxygen generates flammable vapor causing a steady rise in temperature and results in a fire. The major characteristics of fireside are it extends exponentially with time. Hence, timely detection of fireplace is vital for avoiding a serious accident. All fire incidents can be divided in many ways depending on the cause of fire outbreak, but broadly there are two types of fires, one is natural and other is manmade. Forest fires will be either because of natural or manmade reasons. All residential and non-residential structural fires are mostly manmade.
Therefore, in Nigeria where the research was carried out, the activities that was conducted is to design and construct a Fire Alarm System.
1.3 Statement of Problems
Investigation revealed that there are number of fire alarm systems in the market, they use different model of matched transmitter and receiver to achieve excellent stability of frequency for signal transmission. Whether using photoelectric or ionization chamber, the vital element is sensitivity to detect the presence of the smoke. Some of them have built-in fixed and rate-of- rise heat detector. Straight-down and side-view configuration of video camera are also available beside glass-break detectors and panic transmitters. Furthermore, low standby current on sleep mode will save power. There is a new model which operates at very high sensitivity.
1.4 Aim and Objectives of Study
The aim of the study is to design and construct a Fire Alarm System. In achieving this aim, the following specific objectives were laid out as follows:
- To build a circuit that detects the fire and activates the Siren Sound or Buzzer.
- To construct a device that will detect the unwanted presence of fire by monitoring environmental changes associated with combustion.
- To design a system that will detect fire in the right time and prevent any damage to people or property.
1.5 Significance of Fire Alarm System
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.
A feature of most monitoring services is the ability to keep special information on the residence which comes up on the computer screen whenever an alarm is received from that home. Thus, if there is a disabled person in the home who needs special assistance this fact will be known to the operator and can be passed along to the fire department when they are called.
This study will be of immense benefit to other researchers who intend to know more on this study and can also be used by non-researchers to build more on their research work. This study contributes to knowledge and could serve as a guide for other study.
1.6 Scope of Study
The scope of the research is focused on the Design and Construction of a Fire Alarm System. The system detects the fire in ambiance at very early stage by sensing smoke or/and heat and raise an alarm which warns people about the fire and furnish sufficient time to take preventive measures. It not only prevents a big losses caused by deadly fire but sometimes proves to be life savers.
The major components of this device is 555 Timer IC and thermistor which is the sensor - which will sense the fire (temperature rise in surrounding), and trigger the alarm.
1.7 Limitations of the Study
During the course of this study, many things militated against its completion, some of which are:
- Time Constraint: The time frame given to accomplish this project was very short due to school academic calendar and it was carried out under pressure which made the researcher not to implement some necessary features.
- Research material: availability of research material is a major setback to the scope of the study.
- Frequent power failure: This made the researcher append more money on fuel to ensure sustainable power.
- Financial Constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet).
1.8 Methodology
To achieve the aim and objectives of this work, the following are the steps involved:
- Study of the previous work on the project so as to improve it efficiency.
- Draw a block diagram.
- Test for continuity of components and devices,
- Design and calculation for the device was carried out.
- Studying of various component used in circuit.
- Construction of the circuit was carried out.
- Finally, the whole device was cased and final test was carried out.
1.9 Organisation of Research Work
The work is organized as follows: chapter one discuses the introductory part of the work, chapter two presents the literature review of the study, chapter three describes the methods applied, chapter four discusses the results of the work, chapter five summarizes the research outcomes and the recommendations.
1.10 Application of the Project
Fire alarms are prime necessities in modern buildings and architectures, especially in banks, data centers and gas stations.
1.11 Parts of Fire Alarm
Fire alarm composed of the following parts:
- Primary Power Supply: Commonly the non-switched 240 Volt Alternating Current source supplied from a commercial power utility. In non-residential applications, a branch circuit is dedicated to the fire alarm system and its constituents. "Dedicated branch circuits" should not be confused with "Individual branch circuits" which supply energy to a single appliance.
- Secondary (backup) Power Supplies: This component, commonly consisting of sealed lead-acid storage batteries or other emergency sources including generators, is used to supply energy in the event of a primary power failure.
- Initiating Devices: This component acts as an input to the fire alarm control unit and are either manually or automatically actuated. Examples would be devices pull stations, heat detectors, or smoke detectors. Heat and smoke detectors have different categories of both kinds.
