A Fire Alarm System | Engineering Essay
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It is more prudent to head off a disaster beforehand than to deal with it after it occurs. Fire alarms are one of the most useful ways to avoid fire deaths. A fire alarm system is part of the total security system providing fire protection. Installation of fire alarm system gives rise to numerous benefits such as safety of occupant of a building, reducing loss of property or early notification to fire department.
Two hundred years ago, early Americans fire alarms were very creative. The different ways to announce a fire were by blowing whistles, ringing church bells or even shooting guns into the air. Due to the creativeness and inventiveness of early scientists, alarm systems were revolutionized. They were using the telegraph technology . Ensuing decades into the 21st century produces multi-functional community fire reporting methods through wireless transmitter. Consequently, alarm systems were installed in private houses and business for security reasons. The first fire alarm system was created in the year 1658. There was no technology used. The New York's first fire department employed eight men. Nightly, the "firemen" were walking the streets to check for fires. In the 1850's, the Australian created the hand-shaken wooden rattle alarm which awoke people from impending harm. After the creation of the telegraph, forthcoming fire alarms were improved by employing this technology. Using telegraph technology, in 1852, William F. Channing and Moses Farmer designed two fire alarm boxes with each containing a telegraphic key. With reporting a neighborhood fire, the person cranks the attached handle on the box releasing the key to send out a message of the box number to a central alarm station. Upon receiving the message, the telegrapher at central headquarters sent the corresponding address of the box location to the fire department response team . Consequently, more advance technologies were used to create fire alarm which made the latter more effective in numerous ways.
One of the most common types of fire alarm system is the smoke alarm. A smoke alarm is one that uses a smoke detector as a device that detects smoke to activate the alarm system. Although the use of smoke detector as sensing element is mostly used in fire alarm, the latter is not fully effective. According to Journal of Safety Research, improved efforts are needed for the functional use of smoke alarm to saves more lives. To improve the functioning of fire alarms, the type of sensor used must be changed .
Sensors play a fundamental role to any measurement and automation application. A sensor is a device that converts a change in a physical condition to a measurable response. One of the most useful types of sensor used in fire alarm is the temperature sensor. A temperature sensor is one that converts heat energy in electrical energy. That is, the temperature scale is calibrated accordingly to a voltage scale. There are several temperature sensors, a few of them are, thermocouples, thermistors and thermostats among others .
In most of the electronic circuitry, signals from sensors are processed using a microcontroller. A microcontroller is a small computer mounted on a single integrated circuit. It is divided into different section namely the processor core, memory and programmable input and output peripheral. The different types of microcontroller used are Programmable Logic Device (PLD), Programmable Logic Controller (PLC), Peripheral Interface Controller and the most recent one the Matrix Industrial Automotive Controller (MIAC). The MIAC is an industrial grade control unit which can be used to control a wide range of different electronic systems. Programming the MIAC system is typically done using Flowcode, which is a simple microcontroller language that uses the same principle as flowchart.
In this project, a fire alarm will be installed in a chemical laboratory. One of the crucial aspects while working with chemical substances is temperature. The system which will be created will have as main objective to regulate in temperature of the laboratory and in case of fire to activate the fire alarm and its entire component. The system will have as input a temperature sensor which will read the temperature of the room. The signals from the temperature sensor will be used as the microcontroller input. The output of the microcontroller will vary according to the temperature of the room. The three main functions of the microcontroller are to activate the air conditioner system when the temperature of the room is high. Furthermore, at low temperature the microcontroller will activate the heater system. Finally, at very high temperature, that is in case of fire, the system will activate the fire alarm, the sprinklers, close the windows and doors after all occupants of the laboratory have left the premises. Closure of the windows and doors prevent the exposure of the fire to oxygen and avoiding the fire to expand on a larger scale.
1.2 Aim of the project
The aim of the study is to design a system which will be used in a chemical laboratory. In case of very high temperature in the room denoting a fire, the system activates a fire alarm and all its components. Moreover, when the temperature of the room is low the heater system will be activated and when the temperature is high the air conditioner system will be activated. The system will have as input a temperature sensor and the MIAC as microprocessor to process the signals from the temperature sensor and activate the required system as its output.
1.3 Objectives of the Project
The objectives of the project are as follows:
To understand the structure and operation of the MIAC.
To study the flowcode programming technique.
To understand how to interface MIAC to the inputs and outputs.
To design a program that meets the requirements of the system.
To build a model of the system with all its components working accordingly.
1.4 Structure of the report
1.5 Brief Literature Review
In the United State (US), most lethal injury that occurs in houses is caused by fires and burns. One of the most persuasive ways to prevent death and injury from fire is by installing a fire alarm. It is an effective method if regular maintenance is done on the alarm system regularly. Statistic shows that 95% of the houses in the US have a fire alarm; there is still a high percentage of fatal injury caused by fire. Due to lack of maintenance of the alarm, the latter tend to be ineffective. According to the finding in the Journal of Safety , there's a huge gap between number of smoke alarm present and the number of lives saved in fire tragedy. In order to improve the efficiency of alarm, campaign shall be done to make people aware of the danger if maintenance is not performed regularly. Accordingly, the most vulnerable group of people from fire death is the young children, older adults and the disabled person.
Alarm system is an important aspect in processing industry. In industry where products are manufactured in line processing, alarm system plays a fundamental role in alerting the operators that a strange event has occur or equipment is not behaving according to normal conditions. For safe operation of the alarm system, regular alarm assessment is required for alarm management life cycle . Regular assessment provides feedback for fine tuning the system resulting to a good working condition.
There are two aspects in fire alarm design. The first aspect, the engineering aspect consist of the designing the alarm generating algorithm. The algorithm can be simple limit checking on a raw process to much complex one such as using machine learning tools for fault classification. The second aspect of the alarm system is the way that errors are notified in order that necessary action is taken at the right time to solve for the problem that occurred. Human Machine Interface  is an elemental part in the second aspect.
In order to test for the performance of alarm system with respect to the first aspect of alarm design, graphical tools are used. Two graphical tools which are commonly used are firstly the High Density Alarm Plot (HDAP) and the Alarm Similarity Color Map (ASCM). The High Density Alarm Plot is an appropriate tool for visualizing large amount of alarm data of a plant over a selected time range. The HDAP gives a global picture of the alarm system without getting a deeper insight of how the latter works. The HDAP has the capability to identify visual periods of plant instability. By instability we mean the period of time where a high number of alarm is activated simultaneously in a short time period. The Alarm Similarity Color Map (ASCM) is software for graph plotting. There are several steps in plotting the ASCM graph . The steps are follows under the assumption that the co-occurrence of two events follow a homogeneous Poison process and calculate the probability that the number of overlaps is less than the maximum overlaps calculated for various lag.
In most of the industrial system, the aim of the factory is to ensure that operation is run fluidly and without any abrupt interruption. Most modern industries use latest technology to ensure that the work is done correctly and effectively. The latest technologies consist of using sensors to gather information. Sensors are used to communicate the physical and environmental conditions under which the plant is running . Different sensors are installed at various places in the factory to capture the information required. Under normal conditions, the plant shall operate smoothly. On the other hand, when a sensor captures a change in any one of the variables, operators are notified trough an alarm system. An activated alarm system indicates an abnormality in the plant processing .
In order to minimize the risk of injury or even death of people inside the plant, the fault should be identified rapidly and remedy actions shall be taken as soon as possible. Using sensors to gather information of the different variable, the running conditions of the factory are monitored thoroughly minimizing the risk that an abnormal behavior goes undetected.
In contrast, with small changes in variables being monitored, sensors are prone to capture unimportant events. The slight changes in variables activate the alarm unnecessarily; this is known as nuisance alarm. Nuisance alarm conveys false impression of the true nature of the problem . False alarm contributes to a more stressful working environment thus reducing the performance of operator to response to true alarm. In 1994, 11 minutes prior to explosion in the Texaco Milford Haven Refinery the two operators present at that time had to distinguish, acknowledge and act on 275 alarms . We can conclude that for the proper operation of a factory, it is important to manage the alarm system effectively.
There are different approaches to detect faults. Fault detection can be globally classified into two groups, namely model-based and signal processing based. Model based fault detection is more present in areas such as control theory and engineering . Since it is very ambitious to reach precisely a mathematical model in practical situation, the use of model-based scheme is limited. Moreover, it is a tedious task and it is not always sure that the mode will be accurate enough to reflect the practical situation.
The most popular fault detection system used nowadays in factories is simple limit checking of a directly measured variable . This system is easy and simple to implement. In spite of its simplicity, the threshold level should be selected properly which directly affects the number of false and missed alarm. A false alarm is one that is raise without the presence of any abnormality in the process . Missed alarm is an alarm that is not raised in the presence of fault . When a wrong threshold level is chosen in the simple limit checking method, it results in greater number of false and missed alarm.
When a fault occurs, the alarm systems may not be activated instantaneously. This occurs due to different delays of the system. There are different reasons causing this delay to a system. The different types of delay are network delay, bad implementation delay, sensor failure and data loss delay among others . Moreover, the way the parameters of the alarm system are set can cause also rise the delay time of the system to response to a change in variables. To construct a trustworthy and effective alarm system three performance specifications should be taken into consideration namely false alarm rate, missed alarm rate and detection delay.
From the information gathered so far, we can deduce that there is a need to research on new types of effective fire alarm system. Since the actual fire alarm systems are not effective as they shall be, an intelligent and practical system will be developed to serve for this purpose. The developed system will be controlled by a Matrix Automotive Multimedia Controller. The proposed system shall successfully deal with fire outbreak and also regulate the temperature of the room.
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