This paper is concerned with fire safety in buildings and structures, and other related studies and researches on fire safety. This has covered some aspects of fire engineering, prevention, the materials used in furnishings and structures and their susceptibility to different types of fires, and many other aspects of fire safety.
Numerous studies have been conducted on fire safety involving materials used in furnishings and structures. We have provided an analysis on the studies and researches on fire safety, and a meta-analysis on the studies to arrive at a clear understanding of fires and materials.
Some of the British codes on fire safety and engineering are cited, with analysis. Codes strived to contain fires not only in a building but also eventually within a building. Fire safety in buildings and structures initially involves careful engineering which requires accuracy and scientific study for engineering application.
Fire safety engineering provides adequate fire safety precautions in a complex building or structure that accommodates a departure from the prescribed performances in any specific area by taking other higher or compensatory measures in another area.
There are laws, or codes, that should be followed on the designs and engineering of buildings and structures. The use of a fire safety engineering approach enables a more precise design necessary for the assessment of new and complex projects.
However, laws or codes on fire safety and engineering are perceived as inflexible, and also seen as prescriptive regulations. Though they have served us well in the past, some are now seen as inadequate to meet the new challenges of new materials and innovative design.
This paper is concerned with fire safety in buildings and structures, and other related studies and researches on fire safety. This will cover some aspects of fire engineering, prevention, the materials used in furnishings and structures and their susceptibility to different types of fires, and many other aspects of fire safety. It is important to note that fire safety is a broad concept that carries many subtopics which are interrelated but relevant to this Report. Fire safety is a general term. It encompasses fire prevention and other fire safety engineering methods, and topics on materials and equipment for fire safety and prevention.
First of all, fire prevention is everyone’s concern. But huge responsibility lies in the fire chief who is forced to deal with emergency incidents involving buildings and structures. Moreover, building officials are responsible for ensuring that structures are constructed and maintained within guidelines prescribed by law (Diamantes 84).
General as the subject of fire safety may seem, some aspects can be termed as specifics and particular to fire safety. Fire prevention is safety itself, and this may correlate or link with the use of the right materials prescribed by the Code to prevent huge damage in case the fire is already occurring. In schools and offices, there are fire prevention exercises such as fire drills to prepare people for any eventuality or conflagration.
To prevent fire and conduct fire prevention measures is to prevent, or at least reduce, fire loss.
This paper aims to define the risks of fire damage, fire safety, and engineering structures that should serve as models for safety and fire prevention. It is also the aim of this paper to look for various literature, studies, and researches on fire safety and engineering to aid in our study.
Numerous studies have been conducted on fire safety involving materials used in furnishings and structures. It is the objective of this study to provide an analysis of the various literature consisting of books, journals, and web sources, to arrive at well-defined fire safety measures and engineering in buildings and structures.
The literature involving the studies and researches on fire safety with its many sub-topics and subjects will be discussed, and appropriate analysis and recommendations will also be provided after this paper.
Working on a paper that deals with fire safety and engineering mean working on the vast literature and reading materials present and made available by technological advances. We gathered from magazines, journals, books, and a huge amount of information and data from the internet, websites and online journals, studies, and researches for analysis.
The studies and researches from various authors and experts in the field of fire safety and engineering were sourced out and given further meta-analysis to arrive at a clear understanding of fires and materials associated with fast fire, quick fire, and other sorts of fires. These studies and researches added with our analysis allowed us to provide a discussion, and to arrive at a conclusion and recommendations.
Relevant Historical Facts
Over two hundred years ago, firefighters felt a sense of accomplishment if they held fire to the neighborhood of origin, let alone a particular block. As apparatuses and procedures improved, the fires grew smaller in magnitude, reducing down to small groups of structures and individual buildings. (Brannigan 80)
The first recorded attempts at fire prevention and protection took place in Rome in about 300 B.C. Slaves were organized into a combination night watch and firefighting force called the Familia Publica. Then, in about 24 B.C., the Roman Emperor Augustus instituted perhaps the first municipal fire department, the Corps of Vigiles, who performed fire patrol and fire-extinguishing duties, with members assigned to specific functions such as water supply or pump operation (Diamantes 4).
In England during A.D. 1000, there were attempts at preventing fire by regulating public behavior. In 1066, William the Conqueror decreed that all home fires were to be extinguished and covered every evening, at a time signaled by the ringing of a bell. (Diamantes 4)
In A.D. 1666, the great fire of London occurred, following on the heels of the bubonic plague or “black death”, with 17,000 people dead in the City of London. The fire, which originated in kindling stored near the oven of King Charles’s baker, burned for 5 days and nights, destroying 13,200 homes, including churches, warehouses, boats, and barges. After 2 years, the Parliament enacted the London Building Act.
After the great fire of London, a physician named Nicolas Barbon founded a fire insurance company. This first step of Barbon’s grew into the London Fire Office which eventually led to the formation of a fire brigade to extinguish fires in insured properties, the precursor to the modern fire service. (Diamantes 5)
In the early 20th century, codes on fire prevention and safety were instituted. Many concerns were brought out. Some focused on terminologies, out of which the term conflagration was eliminated. Codes strived to contain fires not only in a building but also eventually within a building. Limiting fire spread from building to building is accomplished through several means: restrictions on area/height of a building, limits on the combustibility of roofs and exterior wall surfaces, minimum separation distances between buildings, limits on openings in exterior walls (doors and windows), and fire-resistive exterior walls (Brannigan 80).
As mentioned in the introduction, preventing fires means reducing fire losses. Fire losses have escalated. With expensive materials and furnishings in buildings and structures, fire losses have multiplied. For example, in 1910, the per capita fire loss was $2.32; this figure has tremendously risen in 1999 to $36.80. Total fire costs include not only direct fire damage but also the costs of preventing and controlling fires. While the cost of fire losses has continued to rise, the number of deaths from the fire has, fortunately, declined slightly. (Schroll 1)
Losses and their costs are typically divided into human, direct, and indirect components. Human loss includes the pain and suffering that people incur as a result of the fire.
Brannigan states that there are many terms used to describe materials in advertising or building codes. Some examples are fire-rate, fire-proof, flameproof, self-extinguishing, slow-burning, flammable, non-flammable, fire retardant, nonburning, fire-resistant, and noncombustible. Many of the meanings of these terms are misleading. For example, the term inflammable may still be found in products and advertisements. For many years, the government has striven to eliminate the term from fire protection literature because it is confusing – some people may think it means not flammable. (Brannigan 81)
Fire, according to Schroll, “is a rapid, self-sustaining oxidation accompanied by the evolution of varying intensities of heat and light; it is a chemical process of decomposition in which the rapid oxidation of a fuel produces heat and light”. The basic elements of fire are fuel, heat, and oxygen. (Schroll 10)
Ignition is a series of very rapid chemical reactions between a fuel and oxygen (usually from the air), releasing heat and light. The three elements have to be present to have combustion (Stallard and Abrahams 4).
Flashfire is defined as a fire that propagates through a fuel-air mixture as a result of the energy released from the combustion of that fuel; to cause the fire is to only have an ignition source. This spreads so fast over flammable liquids or through gases.
“Flash fires are a special form of fire hazard that combine the different aspects of ignitability, flammability, heat release, and flame spread” (Hilado and Murphy 82).
Another term is flashover which is defined by Hilado and Murphy as “a stage in the development of a contained fire in which all exposed surfaces reach ignition temperature more or less simultaneously and fire spreads throughout the space and flames appear on all surfaces” (83).
Smolder is defined as to burn without flame, whilst smoldering is combusting without flame, usually with incandescence and moderate smoke. Some materials, like upholstery fabrics and cushioning materials, have a susceptibility to smoldering that is a well-known fire hazard. (Hilado and Murphy 77).
Heat Release – The amount of heat released from material and the rate at which that heat is released are relevant to fire safety because they influence the temperature of the fire environment and the rate of fire spread, and as a result, the severity of burn injuries and the extent of property damage (Hilado and Murphy 90).
Heat transfer is what allows a fire to spread and plays a major role in loss control efforts. Fire travels through four methods of heat transfer: direct flame contact, convection, radiation, and conduction. Direct flame contact is the movement of the fire from one area to another by direct contact with flame. It is responsible for the initial spread of the fire. (Schroll 17)
Smoke is “defined as a visible nonluminous, airborne suspension of particles, originating from combustion or sublimation” (Hilado and Murphy 91). Smoke is an important fire response characteristic because visibility is a factor in the ability of occupants to escape from a burning structure, and in the ability of firefighters to locate and suppress a fire. Smoke density is a measure of fire hazard, in that an occupant has a better chance of escaping if the routes of escape are visible, and firefighters have a chance to see through the smoke.
Trends in Fire Safety Engineering
Architects and engineers and those involved in the designs of buildings should be aware of the complexities of fire science. They should have adequate knowledge of fire in its key stages like ignition, fire growth, and other combustion aspects to incorporate this knowledge in their design or architectural processes of the building.
Fire safety in buildings and structures initially involves careful engineering which requires accuracy and scientific study. Like in other engineering disciplines, this is aided with experience and judgment. Engineering involves the need to evaluate fire hazards and risks and to offer fire safety strategies and designs based on performance, not a prescription. The tools supporting fire safety engineering are the calculation methods (sometimes called models) that describe the measurements, relationships, and interactions, and any necessary test results. (Christian 3)
In other words, with engineering, everything is carefully studied and planned. As in the words of Christian (3), it involves performance and not a prescription. Prevention, on the other hand, includes experience dealing with fires, or the institution of safety measures to prevent or deal with fire.
Another definition of fire safety engineering is that it is “the provision of adequate fire safety precautions in a complex building or structure that accommodates a departure from the prescribed performances in any specific area by taking other higher or compensatory measures in another area” (Christian 3). The concepts of fire safety engineering may be applied to any situation where the fire is a potential hazard (Purkiss 1).
There are always risks when it comes to fire, and they have to be assessed. Fire risk is composed of:
- The potential for harm (or hazard).
- The likelihood of occurrence.
- The likelihood of exposure (Beyreis and Castino 21).
In this aspect, risk assessment is very important. The importance of risk assessment has been to reduce the combined effect of these three elements to an acceptable level (Beyreis and Castino 21).
Moreover, engineering always involves measurements and relationships, including formulas, diagrams, and calculations to arrive at a scientific outcome of a particular project. The fire safety engineering approach may have benefits over the prescriptive approach. It takes into account the entire fire safety package and provides a more fundamental and sometimes economic solution than traditional approaches to fire safety.
There are laws, or codes, that should be followed on the designs and engineering of buildings and structures. For British Standards, we have BS 5588-0, which is adequate. BS 7974 is intended for use to develop and assess fire safety engineering proposals. The use of a fire safety engineering approach enables a more precise design necessary for the assessment of new and complex projects.
But sometimes, laws or codes on fire safety and engineering are perceived as inflexible and seen as prescriptive regulations. Many see them as inadequate to meet the new challenges of new materials and innovative design (Christian 3). Sophisticated designs need sophisticated engineering materials and methods, especially with the new high-technology apparatuses in the 21st century.
PD 7974, or application of fire safety engineering principles to the design of buildings, is structured as follows:
- Part 0: Guide design framework and fire safety engineering procedures;
- Part 1: Initiation and development of fire within the enclosure of origin (Sub-system 1);
- Part 2: Spread of smoke and toxic gases within and beyond the enclosure of origin (Sub-system 2);
- Part 3: Structural response and fire spread beyond the enclosure of origin (Sub-system 3);
- Part 4: Detection of fire and activation of fire protection systems (Sub-system 4);
- Part 5: Fire service intervention (Sub-system 5);
- Part 6: Evacuation (Sub-system 6) (in preparation);
- Part 7: Probabilistic fire risk assessment (Sub-system 7) (In preparation). (Christian 4)
These principles enable the engineer to properly plan the fire safety framework for a certain building or structure. But this has to be modified to meet the new challenges in modern buildings. Engineers and building designers should be able to follow regulations but at the same time have to be innovative and creative in instituting changes brought about by technology.
The International Organization for Standardization (ISO) has produced a comprehensive Technical Report that has now been published by BSI as BS ISO/TR 13387, Fire safety engineering. In eight parts, the Technical Reports were prepared by ISO Technical Committee TC/92, Fire safety (Christian 4).
Not all laws are for fire safety
Whilst we talk of codes and laws on fire safety engineering, some authors argue that laws sometimes are a hindrance to proper institutions of fire safety measures. Bengtson and Hägglund state that recently extensive efforts have been made to create analytical models by which it is possible to judge the safety level objectively, and these were because of the following reasons:
- As the costs of fire safety measures are increasing, cost-effectiveness is of great interest.
- Architects and consulting engineers have found that rigid praxis, inflexible building codes, and insurance recommendations very often are a hindrance to an effective design of a building.
- By quantitative analysis, you wish to obtain information on the effectiveness of new types of measurement systems without waiting for experience from real fires (Bengtson and Hägglund 667).
Causes of fires
Causes of fires can be attributed to poor building design, inadequate emergency procedures, and lack of protective devices like automatic sprinklers. Aside from the building design, fires are exacerbated by combustible interior furnishings. (Clinton 8)
Fire prevention in buildings and structures should include:
- Installing fixed protective devices as sprinkler systems;
- Constructing rooms that are contained areas, to prevent fires from spreading; and
- Limiting the use of combustible materials in hotel furnishings.
Clinton says that if a building is completely protected by an automatic sprinkler system, it might not be necessary to create as many contained areas (8).
Fire safety should be an initial thought of consideration for hoteliers when decorating hotel interiors by limiting the number of combustible materials in the furnishings. Combustible materials which are called “fuel load” can be minimized if they are used only as floor covering. Wood paneling should be treated with flame-retardant chemicals.
Likewise, fire control is another step to make once the fire has started. Some agents used in fire control are halogenated hydrocarbon, also referred to as halons. The two most common halons used for fire control are 1211 and 1301. Halon 1211 is typically used in portable fire extinguishers, and 1301 is normally used in installed systems. The halon agents extinguish fires primarily by interrupting the chemical chain reaction. Their major advantage is that they leave no residue, which makes them especially suited to computer and delicate equipment protection. Halon is stored under pressure as a liquid, but when discharged, it rapidly vaporizes to a gas. (Schroll 22)
Description of equipment
Some equipment or devices we wish to discuss here involve protective devices for fire safety.
Fire warning and detection systems must be properly designed, installed, and maintained. Installation and commissioning certificates should be obtained wherever a fire alarm system is installed.
Fire Detection Alarm
A fire detection alarm system is a key element among the fire protection features of any building (Moore 5).
NFPA defines a fire alarm as “a signal initiated by a fire alarm-initiating device such as a manual fire alarm box, automatic fire detector, water flow switch, or another device in which activation is indicative of the presence of a fire or fire signature” (NFPA Glossary of Terms, and. in Craighead 143).
A fire detection alarm is one of those needed in fire safety engineering to prevent further damage caused by the fire, or to warn the owner, or authorities such as the fire department, and the general public. Early detection can lead to early suppression of the fire and prevent it from spreading before it could cost much damage to the building or structure.
Moore says that ‘fire alarm systems play an essential role in protecting property and lives from fire’ (13).
The user of the fire alarm system must define the reason why the system is being provided. This step will identify the protection goals of the user and also the external factors that may influence the fire alarm system installation. The user may determine that the protection goal is the preservation of the lives of the persons occupying the building. Such a life safety goal and the protection features it dictates will help determine the type of fire alarm system. (Moore 5-6)
Types of Signals in Fire Alarms
Fire alarm systems provide three types of signals:
- Alarm Signal – this provides a warning of fire danger that requires immediate action;
- Supervisory Signal – indicates that action is needed in connection with the operation of other fire protection systems that are being monitored by the fire alarm system. Such systems may include extinguishing or suppression systems, such as automatic sprinkler systems, carbon dioxide systems, dry chemical systems, foam systems, and gaseous agent systems. They may also include the supervision of guards who make fire patrol tours throughout the protected premises.
- Trouble signal – indicates a fault in a monitored circuit or component of the fire alarm system or the disarrangement of the primary or secondary power supply.
Classification of Fire Alarm Systems
Fire alarm systems are classified according to the functions they are expected to perform. The basic components of each system are:
- A system control unit
- A primary, or main, power supply
- A secondary, or standby, power supply
- One or more initiating device circuits or signaling line circuits to which manual fire alarm boxes, sprinkler water flow alarm initiating devices, automatic fire detectors, and other fire alarm initiating devices are connected
- One or more fire alarm notification appliance circuits to which audible and visible fire alarm notification appliances, such as bells, horns, stroboscopic lamps, and speakers, are connected
- Many systems also have an off-premises connection to a central station, proprietary supervising station, remote supervising station, or public fire service communication center through an auxiliary fire alarm system. (Moore 7)
With the emergence of high-technology, IT, and computer software, and its subsequent introduction and infusion to engineering practices, fire detection systems have also become sophisticated.
An automatic fire detection system plays an important role in cases where effective human detection measures couldn’t be expected. In some countries like Japan, automatic fire detection systems have been obligatory to be installed in buildings for specific uses having a floor space above a certain value as prescribed by the Fire Service Law (Watanabe et al 679).
The following considerations should be noted to ensure fire detection methods:
- From ignition to extinction, there are many fire-developing stages and corresponding systems, each of which consists of many sub-systems and components and achieves the mission under different conditions; and,
- Even if the reliability of a hardware system is high, the system effectiveness will be considerably affected by the human attitude towards the system and fire (Watanabe et al 679).
The United States, the United Kingdom, Europe and the rest of the developed and developing world have all instituted measures for the prevention of fire, and installation of fire detection alarms. Sophisticated fire alarms are at anybody’s disposal for as long as you have the money. And they come in handy, especially with the applicability of the internet and Information Technology.
Roberts says (17) that the “signatures” produced by fire are often used as the basis for detection, and these are heat, smoke, and radiant energy. Humans use their senses in detecting fire. Several factors complicate the ability of any detector to sense fire reliably:
- Different types of fires can have widely divergent fire signatures. For example, some materials burn intensely with little or no smoke, whereas smoldering fires have no visible flame and generally very low heat output.
- The environmental change(s) being monitored must reach the fire detector and must exceed a threshold amplitude and/or rate of change before an alarm can occur.
- Nonfire conditions can produce ambient changes that mimic fire signatures and that may cause false alarms. (Roberts 17)
In selecting the type of fire alarm system for a particular building structure, some questions have to be answered. Moore (5) provides these questions that should be answered by the engineer in a holistic approach:
- What are the protection goals?
- Is the building owner attempting to provide a level of life safety that will meet the needs of the people occupying the building and satisfy the requirements of the local building code and local authority having jurisdiction?
- Is the building owner intent on providing a needed level of property protection?
- Or is the building owner trying to ensure that the mission of the facility is not interrupted by fire?
Moore says that the final answer should be “yes” to one or more of the questions, and with this, the building owner is guided to select the fire alarm system that will meet the needs of the facility (5).
Computerized fire alarms have improved fire detection methods. At present, there is a surge of smoke detectors to increase the efficiency of fire-detection methods.
The addressable fire alarm system uses fire detection devices which are both automatic and manual. These detectors are essentially identical to conventional detectors except that they are equipped with electronic circuitry, usually mounted in a special base, which effectively makes each detector a separate zone. In the event of an alarm, the control can require alarm confirmation from an adjacent detector or can require a repeat alarm from the same detector after a remote reset. (Grondzik et al 1142)
Another fire alarm uses an electronic device known as a photoelectric smoke detector which is a special type of smoke detector using electronic parts or circuitry. Photoelectric detectors detect particles from about 0.2 to about 1,000 microns. Thus, they are useful not only for smoldering fires but also for the smoky fires that characterize the burning of certain plastics and chemicals. (Grondzik et al 1149)
An example is the beam-type photoelectric detector which consists of two separate units: a beam transmitter and a beam receiver, normally wall-mounted on opposite sides of a space, somewhat below the ceiling. They operate on the simple obscuration principle and are best applied in areas that do not lend themselves to the application of spot-type detectors.
Some of these are as applicable to photoelectric detectors are:
- High-ceiling areas such as atria, churches, malls, auditoriums, and the like. In these spaces, ceiling-mounted spot-type detectors present serious maintenance problems.
- Spaces with medium- to high-velocity airflow at the ceiling level. This condition severely dilutes smoke entering the test chamber of a spot detector. Although beam detectors are also negatively affected, their long throw and wide “vision” angle make the dispersion and dilution problems much less serious.
- Closed areas with little airflow, resulting in a hot air layer at the ceiling that prevents smoke from reaching ceiling-mounted spot detectors.
- Environments that militate against spot detector use, such as those that are extremely dirty, corrosive, humid, very hot, or very cold. Beam-type detectors can be physically shielded against these conditions in a manner that interferes only minimally with their light-beam transmission and reception characteristics. (Grondzik et al 1146)
The automatic fire detection systems involve a sensor network plus associated control and indicating equipment. These sensors detect heat, smoke, or radiation and it is usual for the control and indicating equipment to operate a fire alarm system. (Billington et al 7.34)
Automatic fire detection systems are not normally needed in non-residential occupancies but are needed in the following circumstances:
- Where it is necessary as part of a fire protection operating system, such as a pressurized staircase or automatic door release mechanism;
- Where a fire could occur unseen in an unoccupied or rarely visited part of a building and prejudice the means of escape from the occupied parts. (Billington et al 7.34)
The Air-Sampling Detection System is another system that takes advantage of the high sensitivity of laser beam-based photoelectric smoke detection. Instead of waiting for air that may be carrying incipient smoke particles to reach the detector by thermal currents, this system samples air throughout the protected space by aspiration and brings it to the detector for testing. The aspiration and air conduction system is simply a piping system with holes at sampling points and is powered by a fan. The advantage of this type of system is that air throughout the space is sampled, thus, in effect, converting each sampling opening into a highly sensitive laser-beam detector. (Grondzik et al 1148)
Some precautions have to be instituted on air conditioning systems. This is because they exacerbate the fire if no automatic protection is instituted. Some codes require an electrical hookup between air-conditioning units and smoke-detection systems that automatically shuts off the air-conditioning system when smoke sensors are activated. Although this method helps control the spreading of smoke, it will not remove smoke unless the units are also provided with manually operated overrides. Some designers prefer to have the air-handling system switch to “fire mode” once a signal from smoke sensors has been received. In fire mode, the supply ducts furnish fresh air to floors above and below the fire floor, thus pressurizing them, while return ducts pull smoke from the fire floor. (Clinton 8)
Fire-fighting devices initiated either manually or by the fire detection system are installed in buildings and other structures. Such automatic devices vary depending on the type of fire to be expected but they generally operate by smothering the fire and denying the fire any source of oxygen.
One of the devices that reduce the temperature of burning materials is sprinklers. Sprinklers effectively act by reducing the temperature of the burning contents. Any fire-fighting system installed as part of the fabric of the structure should be supplemented by the supply of both suitable portable fire extinguishers and by hose reels for local fire fighting.
In the words of Brannigan (80):
The concept that eventually led to the modern sprinkler system was introduced more than 100 years ago when it was discovered that early mechanical application of water to an incipient fire was the key to reducing property damage in industrial facilities.
The value of installing an automatic sprinkler system for life safety and property protection has been well documented over many years of service in a variety of specific applications. The sprinkler system should also be maintained in such a condition that it is always ready to discharge water on a hostile fire. (Leber 43)
Large structures also require sprinkler systems installed either as a requirement from the insurance company to reduce property losses or as part of the trade-off between active and passive systems allowed by some regulatory bodies, e.g. England and Wales Building Regulations, Approved Document B (Department of the Environment, 1992a, qtd. in Purkiss 8).
In some systems, a line of sprinklers is located around the escalators. The sprinklers are shielded from one another to prevent one sprinkler from cooling the other. Although these sprinklers may extinguish a nearby fire they would not affect smoke or gases moving from a fire, not in the immediate vicinity. (Brannigan 102)
In designing the sprinkler systems, the architect’s specifications must be reviewed. A section should be included for the fire sprinkler installation. The source of the building’s water supply is noted, usually from the civil or plumbing drawings. The HVAC drawings provide information on the whereabouts of the larger air handling units and if any unit heaters are to be installed. On all drawings, any noted elevations provide the best information possible for deciding on the optimum fire sprinkler pipe elevations. (Bromann 5-6)
Hydraulically Operated Waterflow Alarms
Hydraulically operated water flow alarms are also called “water motor gongs”, which operated very much like a miniature version of the water wheel that operated the mill shafting of a textile mill. When an automatic sprinkler fuses in a fire, when a pipe breaks, or when a fitting develops a significant lea, water is diverted through an open alarm control valve to a nozzle assembly that directs a stream of water against the paddles of a water wheel. Then when the wheel turns, it operates a striking mechanism that repeatedly strikes the shell of a large gong, which then produces a loud clanging should that can be heard in the vicinity of the sprinkler riser. (Leber 44)
Electrically Operated Waterflow Alarms
Examples of this kind of electrically operated fire alarm notification appliances are vibrating bells, horns, sirens, chimes, and flashlights. Signals are usually initiated by electrical switches incorporated into some type of pressure- or flow-operated device. (Leber 44)
Household Fire Alarm Systems
Households also need warning systems because many fire deaths are a result of fires in homes. Smoke alarms have great importance in controlling fire in households. Actual fire tests in residential occupancies have shown that measurable amounts of smoke have preceded measurable amounts of heat in almost all cases. (Bukowski 79)
The fire alarm system should monitor all fire alarm initiating devices. Examples are manual fire alarm boxes: heat, smoke, radiant energy, fire-gas, or other fire detection devices; and the discharge of automatic sprinkler systems and other fire suppression or extinguishing systems, such as dry chemical, foam, foam-water, water mist, carbon dioxide, and other gaseous agents. Early detection of fire can contain the fire.
Fireguard services generally serve three purposes in protecting property against fire loss: (1) protect the property at times when the management is not present; (2) facilitate and control the movement of persons into, out of, and within the property; and (3) carry out procedures for the orderly conduct of some operations on the property. (Wenzel 89-90)
Further Prevention: Maintenance
As time goes by, improvement in the understanding of fire and its behavior enables designers to better design fire alarm systems to achieve specific objectives and levels of performance. But this has to be constantly assessed and maintained, otherwise, some go wrong. Murphy’s law states: “anything that can go wrong will go wrong.” (Cholin 55)
System reliability should be maintained as high as possible. Reliability is essential for fire alarm systems. Fire alarm systems are intended to fulfill three essential objectives:
- Ensure life safety,
- Conserve property, and
- Ensure continuity of the mission of the site.
According to Cholin (55), the highest objective is life safety, and the second is mitigation of property damage through the timely actuation of automatic fire extinguishing systems and transmission of fire alarm signals to the fire service.
Periodic inspections of equipment and high-risk areas can prevent several unsafe fire conditions. A weekly inspection program should be instituted that includes the following procedures:
- Maintenance areas, loading docks, stockrooms, and other areas with large amounts of storage should be kept clean and accessible;
- A daily inspection should be made of all service areas, lounges, restaurants, kitchens, and unsprinklered areas containing temporary combustibles;
- Boiler rooms and all gas and oil-fired equipment should be checked to ensure that safety controls are operable;
- If the facilities are equipped with automatic sprinkler protection, the sprinkler control valves should be locked open and periodically checked, both visually and physically, to ensure they remain open;
- Sturdy locks and chains should be used to discourage tampering; and
- Proper supervision and precautions should be taken whenever a fire-service control valve is shut off or fire-protection equipment is taken out of service (Clinton 9).
Reliability of Electronic Components
The reliability of a fire alarm system can be computed, using tested formulas, considering the reliability of the individual electronic components has been thoroughly studied and documented. Each general type of electronic component exhibits particular and predictable failure modes, and understanding these failure modes leads to understanding the impact such a failure may have on a fire alarm system component. For example, semiconductor devices fail either to a short or open circuit. The components are integrated circuits which consist of simple semiconductor diodes and transistors. (Colin 59)
Materials involved in fires have to be examined to determine their safe use.
Hilado and Murphy state that “attention to the design and engineering aspects of materials may be the most cost-effective and in some cases the only means of ensuring their safe use” (76).
Organic material is any material containing carbon, except carbon monoxide and carbon dioxide. Fire is uncontrolled combustion. Unwanted fire is either accidental or deliberate. (Hilado and Murphy 76)
Once a fire is started, we need sufficient information to quantitatively predict three things: the rate of fire spread over the given material in the given configuration, the rate of pyrolysis, and information about the pyrolysis products (Emmons 34).
Many materials are usually involved in each real fire situation. Organic materials present their behavior in laboratory tests; thus, they have to be observed and studied in the laboratory to provide a clear understanding of fire hazards and fire safety.
In their experiment on these materials, Hilado and Murphy wanted to prove that “the physical characteristics and the quantity and placement of the material in the system are often controlling factors, rather than the chemical composition of the material” (77). They further add that there is a big challenge on the part of the designer/engineer to make the best and safest use of the material because there are limits to chemical composition changes that are possible while still retaining desirable performance characteristics in any material.
Hilado and Murphy reviewed the combustibility behavior of organic polymeric materials in terms of several fire response characteristics: smolder susceptibility, ignitability, flash-fire propensity, flame spread, heat release, and smoke (77).
Studies on Fire
Magnusson and Sundström Study
The study was conducted on a Swedish research project about compartment growth and fire spread, one of the subjects of extensive investigations over the last decade. Room fire growth on combustible linings remains a virtually unexplored area.
The project worked on three interacting lines of development, namely:
- The first involves a generation of improved small-scale methods. From an international point of view, the work carried out within the International Organization for Standardization (ISO) is of importance as it opens the way for the replacement of the multitude of national test standards with internationally agreed ones.
- The second involves the development of a full-scale room test procedure.
- The third trend concerns the evolution of mathematical modeling, both of the firing process in the small-scale laboratory apparatuses and the full-scale fire growth (Magnusson and Sundström 47).
The study provided a computational procedure to correlate a full-scale room fire test process and results from the proposed International Organization for Standardization (ISO) small-scale laboratory tests. Derived material characteristics and test room time lag factors were used as input data to an uncomplicated mathematical expression, essentially describing the full-scale test fire process as a concurrent flame spread phenomenon. The study used regression and qualitative regression equations. For thin surface finish materials on a non-combustible base, it was possible to derive a radically simple expression to be used as an indication of the risk of flashover.
It was thought that a first step has been taken in the efforts to use results from small-scale tests to rationally predict full-scale fire growth (Magnusson and Sundström 45).
Hilado and Murphy Study
In another study, Hilado and Murphy reviewed the data on smoldering susceptibility of fabrics and found that smolder susceptibility is not a function of the fabric alone or the substrate alone, but of the specific fabric/substrate combination. The time to ignition, which was carefully recorded, generally decreased with increasing heat flux. Since heat-flux is a function of distance from the heat source and is reduced by intervening materials, placement and design of the material in the system can often determine whether or not ignition will occur in a particular fire situation (Hilado and Murphy 82).
The experiment found that lighter softwoods, such as western red cedar and eastern white pine ignited more rapidly than did the denser hardwoods, such as beech and red oak. The lighter boards ignited more rapidly than did the denser boards, such as hardboard and chipboard. Materials with thermal insulation characteristics can be expected to reach surface ignition more rapidly than less effective insulators that are therefore better heat sinks. (Hilado and Murphy 82)
In testing for ignitability, the physical characteristics of the substrate are important.
Because low density is a desirable feature in organic polymeric materials, from the viewpoint of structural weight, thermal insulation, and consumer appeal, in many applications, the effect of density on ignitability can be offset by the use of ignition-resistant coating and covering materials. Such protective materials include metal films and sheets, and noncombustible materials such as ‘gypsum board and plaster’ (Hilado and Murphy 82).
Murty Kanury Study
Murty Kanury conducted a study related to an experiment in identifying changes in materials and designs to improve the level of fire safety in mobile homes. The tests reported were in a single-wide, full-scale unit, while other tests were also conducted in a quarter-scale unit. The initial fire source employed a specified wood crib, upholstered chair, or gas burner. Wall and ceiling linings were tested. The room geometry, location of the initial fire, and window (or door) geometry were among the other variables considered. (Kanury 99)
The objective of the research, as reported by Kanury (99), was:
- to develop an understanding of the relationship and correspondence between the observation and measurements made on fire growth in compartments of different scales;
- to synthesize the scaling rules to deduce the full-scale compartment fire behavior from the results of small-scale tests;
- to apply these rules to full and quarter-scale data of NBS focusing on the issue of flashover as influenced by linter (space between the top of the door and ceiling) height and wall linings.
Kanury summarized the study by saying that a critical burning rate within the room exists to indicate whether or not flashover will occur and if it does, the time to flashover. This critical burning rate is rather strongly dependent upon the vent opening size. The vent opening size thus appears to do one of two things: ‘a) it regulates the outflow of hot combustion gases and hence the associated convective heat loss; and, b) it regulates the thickness of hot gas layer near the ceiling of the compartment and hence the associated internal augmentation of heating due to radiation from the gas layer’ (100).
Based on the measurement of various temperatures, heat flux, gas concentrations, and smoke, several important conclusions were drawn from the test program. It was found that the hot gas temperature near the ceiling approaches and exceeds a critical value of about 500°C, the phenomenon known as flashover is imminent. Kanury argues that this was probably caused by the development of sufficient thermal radiation from the hot gases and surfaces to result in the ignition of all combustible materials in the room. For a room of a given size, a critical initial heat source strength is required to attain the critical ceiling temperature which is characteristic of a flashover.
Results and Discussion / Analysis
The concept and practice of fire prevention have been observed in recorded history, although two hundred years ago, this was still a very new phenomenon.
When we talk of fire prevention, there are many correlated terms used, examples are fire-rate, fire-proof, flameproof, and so forth. A planner or anyone involved in fire prevention and safety should take note and look for the real meaning of these terms because they are sometimes misleading to the public. For example, the term inflammable is misleading and there are efforts to eliminate it from fire protection literature.
In examining the thermal response characteristics of materials, it is important to note that the physical and thermal response characteristics have a greater effect on their fire response characteristics than their chemical composition.
Fire science is a growing subject in fire prevention and safety. Architects and engineers have to study it in their fire prevention applications.
Fire safety in buildings and structures initially involves careful engineering which requires accuracy and scientific study for engineering application; this is aided with experience and judgment, as in other engineering disciplines. Engineering involves the need to evaluate fire hazards and risks and to offer fire safety strategies and designs based on performance, not a prescription. Safety engineering is much needed in fire safety because engineering is a discipline that involves careful planning.
Laws or codes in our literature review have some advantages, but as noted by many engineers and those involved in fire safety engineering, some of these codes are inflexible or prescriptive in their applications. Incorporating safety measures in structures and buildings should have a careful study by the engineer or architects, and the codes regulating this planning should be flexible enough to give more lee-way for the engineer doing the planning. The principles in the code must enable the engineer to properly plant the fire safety framework. Some experts argue that some laws are a hindrance to the right fire safety measures.
Experience tells us that the causes of fires are due to poor building design, inadequate emergency procedures, and other necessary measures not being implemented, such as automatic sprinklers. Furthermore, interior furnishings exacerbate the growth of fires, or they could be the primary cause of the fire. The materials are very combustible. Engineers and architects should not neglect to install the necessary fire protective devices in buildings and structures. In hotels and buildings for public use, owners should be very careful in installing combustible materials which are said to be “fuel load” to possible fires.
Moreover, fire detection alarms are a necessity in buildings and structures to warn occupants of an existing fire. Computerized fire-detection alarms are now available and at reasonable prices. These alarms are applied with the necessary IT tool or software which can aid the engineer or designer in planning the fire-safety measures in buildings.
Now, high-rise buildings and structures use sophisticated fire detection alarms to warn occupants and maintenance crews of an existing fire. There is also the surge of sophisticated smoke detectors to increase fire-detection methods. The addressable fire alarm system is both automatic and manually operated. The photoelectric smoke detector is composed of a sensitive electronic circuit that provides an alarm in case smoke is detected. Photoelectric detectors can be installed in high-ceiling areas and spaces with medium to high-velocity airflow at the ceiling level. An automatic fire detection system is installed with a sensor and an electronic circuit that detect heat, smoke, or radiation. The air-sampling detection system uses laser beam-based photoelectric smoke detection. Warning and protective devices are also installed in air-conditioning units which may add “fuel load” to an existing fire.
The installation of sprinklers in buildings and structures is now a major requirement under the Code. Sprinklers are automatic devices that switch on when fires occur. They reduce the temperature of the burning contents. Sprinklers are installed in various places in the buildings, and their locations depend on the architect or engineer’s plan. The building’s water supply is noted when designing sprinklers.
In our discussion on the studies on fire, we would like to give focus on the analysis of Magnusson and Sundström’s study on the Swedish research project on compartmental fire, or a room fire. The authors stress that fire growth depends on combustible linings or furnishings in the room. This work gave importance to ISO standards. The work involved the development of a full-scale room test procedure, and the evolution of mathematical modeling, both of the firing process in the small-scale laboratory apparatuses and the full-scale fire growth. Test methods usually for smolder susceptibility used a small-scale mock-up 203 mm (8 in.) wide primarily for comparing fabrics, and a larger-scale prototype 450 by 550 mm (18 by 22 in.) simulating complete assemblies. The ignition source was a king-size nonfilter cigarette covered with one layer of laundered 100 percent cotton bed sheeting material. The study was a scientific application using regression and qualitative regression equations.
The Hilado and Murphy study was about the smoldering susceptibility of fabrics which found that smolder susceptibility is not a function of the fabric alone or the substrate alone but the specific fabric/substrate combination. This experiment found some results stating that lighter softwoods ignite more rapidly than denser woods.
The Murty Kanury study on flashover related to an experiment in identifying changes in materials and designs to improve the level of fire safety in mobile homes. Kanury found that a critical burning rate within the room exists to indicate the occurrence of a flashover which depends on the vent opening size.
Based on the measurement of various temperatures, heat flux, gas concentrations, and smoke, several important conclusions were drawn from the test program. It was found that the hot gas temperature near the ceiling approaches and exceeds a critical value of about 500°C, the phenomenon known as flashover is imminent. Kanury argues that this was probably caused by the development of sufficient thermal radiation from the hot gases and surfaces to result in the ignition of all combustible materials in the room. For a room of given geometry with specified wall linings and a stated window or door opening, a critical initial heat source strength is required to attain the critical ceiling temperature symptomatic of flashover.
Conclusions and Recommendations
In any country, there are laws or Codes on fire safety and prevention but some laws are not any more flexible or effective than many engineers, architects, or building designers, for that matter, find these Codes a hindrance to their job of designing buildings with fire safety measures. In other words, governments should be flexible enough to constantly review their laws on fire safety and prevention.
In the study of fire prevention, it is always important to consider the preparation and the planning of the various needs in preventing fire. Fire can become predictable if fire safety engineering is coupled with scientific application and the right formulas instituted like in many other disciplines.
The essential objectives of a fire alarm system, which are safety of lives of occupants of a building, property protection, and continuity of the site’s mission – can be achieved in the event of fire only if the alarm system functions properly. The proper maintenance and reliability of fire alarm systems should be instituted by the building owner or other persons or authorities concerned. The system elements, like design, equipment, installation, and maintenance, are very critical to the reliability of the system.
The various studies and researches on fire safety and prevention which included the different types of fire, the materials that cause the fire, and other incidents and phenomena on fire, have helped us discuss and analyze fire safety engineering.
Experience and more studies and researches on fire behavior and its causes can help us reduce fire incidents and subsequently fire losses.
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