Fire Hazard Progression in Managing Evacuation - Article Example

1. The main stages of fire development in a compartment are: Ignition, Growth, Flashover, Fully-Developed, and Decay. The Growth phase occurs from Ignition until all combustible materials are affected by the fire, either through actual burning or heating near to their combustion point. Flashover is the rapid phase between Growth and Fully-Developed, when all combustible materials in the compartment ignite. In the Fully-Developed phase, all combustible materials are burning and the maximum temperature of the fire is reached. In the Decay phase, the available fuel and oxygen rapidly diminishes until it is gone, burning the fire out unless more fuel or oxygen becomes available. (NFPA, 2005, p. 28; APAC, 2009) 2. It is necessary to consider fire hazard progression in managing evacuation because the progression may force a change in the planned evacuation route once a fire has started. For example, smoke or flames spreading faster or in areas that have not been accounted for in the evacuation plan might force people to seek different escape routes, increasing the time and distance to escape the fire. (Rasbash, Ramachandran, & Kandola, 2004, p. 302) 3. Evacuation is of paramount importance during the Growth phase of a fire, as soon after Ignition as the fire is detected. Studies in human behaviour in fire emergencies have shown that building occupants often delay the start of their evacuation – perhaps hoping it is a false alarm, or a minor situation that can be controlled with no inconvenience to them. (Proulx, 2007) And if this delay is added to a delay in sounding the alarm and ordering an evacuation in the first place, the risk that some occupants will encounter smoke or flame and possibly become trapped increases. 4. Available Safe Egress Time is the amount of time available for evacuation before fire conditions would make the occupied areas and escape routes unusable. Required Safe Egress Time is the amount of time actually required by people to be able to move from where they are when the fire starts to a safe area. In a properly-designed building, the RSET will be less than the ASET. (n.b., it says on the exam to use a diagram? I don’t know what that means) 5. (This question says “use the information provided in the table below” but there is no “table below” in the file of questions you sent) 6. (This question says “using SPFE formula – see handout”, which is not in the questions you sent.) 7. (This question cannot be done until 5 & 6 are completed.) 8. Five occupant characteristics that influence behaviour during evacuations are age, gender, physical and mental abilities, whether the occupants are asleep or awake, and occupant density in the building. (Chu, et al., 2001) These characteristics determine how the occupants will behave, for example, whether they panic, pause to wait for information or to collect belongings, gather together, or evacuate smoothly. 9. The five factors that influence travel time are: 1. The evacuation distance – How far a person must travel to reach a safe area. 2. The characteristics of the evacuation route – How wide are corridors and doorways that must be passed; whether or not there are stairs, and whether the person must travel up or down. 3. The mobility of the occupants – Age, gender, and the physical and mental abilities of the occupants have an effect on travel time. A disabled elderly person, for example, is much slower than an able-bodied younger adult. The activities of the occupants also affect their travel time, such as whether they are residents or workers, or whether they are asleep or awake at the time of the fire. 4. The number of available escape routes – If there are safe alternate routes, travel time is reduced because the number of people trying to evacuate in any one direction is fewer. 5. Population density of the building – Travel time increases with the number of people in the building. 10. The fundamental principle of escape route design is that it should be possible for any occupant of a building to reach a place of safety within a reasonable travel distance and time. In other words, RSET must be less than ASET. 11. The 45° Rule refers to the separation of alternate escape routes. From any location, the alternative escape routes must be separated by 45° or more, or if they are separated by less than 45°, isolated from one another by fireproof construction, in order to prevent both routes from becoming disabled at the same time. (Approved Document B1, para. 3.9) 12. A ‘prescriptive solution’ is a design that meets general standards that are applied to all similar buildings. A ‘fire engineered solution’ is a design that follows statutory guidelines rather than specific requirements, which allows designers to be more flexible. A building design which follows the requirements for compartmentalisation in Approved Document B1, for example, is a prescriptive solution. An open-design building that compensates by perhaps having a more advanced fire suppression system is an example of a fire engineered solution. 13. The advantage of Approved Document B1 is that it prescribes specific, detailed standards for fire warning and escape for all types of conventional-design buildings. The regulations are clear, and do not require a designer to refer too much to other codes in order to design a safe building. On the other hand, B1 does not provide as much guidance for unconventional designs, or for buildings that were designed and built before the regulations took effect. 14. Direct distance is the actual distance between a point inside a building and an exit. Travel distance is the actual distance a person must cover between that point and the exit. It is longer than the direct distance because of doorways, corridors, stairways, etc. through which the person must travel. 15. The functional requirements in the Building Regulations are: 1. Warning and escape – Provisions must be made to give adequate warning to building occupants, and to provide a means of escape to a place of safety. 2. Fire spread on surfaces – The materials used for surfaces in the building must not increase the spread of the fire or create more heat. 3. Stability of the structure – The structure of the building should remain sound as long as possible in a fire. The interior of the building should be built with compartments – including in hidden spaces – to prevent or limit the spread of the fire inside the building. 4. External fire spread - Walls between buildings should prevent the spread of the fire from one building to another, as should roofs. Sufficient space must be provided between buildings to prevent fire spread. 5. Facilities for fire services – The building should be designed with proper access for fire-fighting and emergency personnel. This includes clear area around the building so that fire equipment can approach, proper availability and placement of fire hydrants, and standpipes and water supply inside the building if appropriate, as well as protected stairwells or fire lifts. 16. A qualitative risk assessment method measures a relative risk of a particular condition of characteristic of a building or its activities, and is a subjective measure. A simple example would be that a building used as a printing shop has a relatively higher risk than one used as an office, because of the greater number of combustible materials such as ink, chemicals, and stocks of paper. A quantitative risk assessment measures an absolute risk, usually in numerical terms, and is an objective measure. A specific calculation of the combustibility of the materials in the printing shop, for example, leads to a quantitative risk assessment. The difference between the two is that a qualitative assessment measures a risk in comparison to some other condition, while a quantitative assessment can be used to measure a risk both on its own or in comparison to another condition. 17. A risk-based fire safety legislation simplifies regulation by replacing specific laws and requirements with a process of risk assessment. This reduces the number of legal requirements the building or business owner must meet, and reduces the burden on fire authorities who are responsible for checking safety of buildings. (Cheshire Fire & Rescue Svcs., 2006) It is also more flexible, because individual buildings are assessed on their own merits rather than on a completely arbitrary set of rules. This allows designers and builders more flexibility in designing buildings. The disadvantages are that there is a greater risk of misinterpretation of the regulations, either by building designers or owners or by the fire authorities monitoring them. Because there is flexibility in the guidelines, a compensation for one prescriptive solution by providing different protection might not always be effective, leading to a problem later that could not have been anticipated. 18. The first branch of the fire safety law addressed new or altered premises, which means that regulations can be applied as the building is being built or re-modelling is taking place. This is simpler to enforce and easier for building owners to abide by, because the regulations can be applied more uniformly, and proper fire safety measures can be applied in the design process, avoiding costly re-working. Examples covered under this branch of the law would be new apartment or office buildings, or buildings converted from one use to another, such as a warehouse turned into a club or restaurant. The second branch of the fire safety law pertained to buildings already occupied, or buildings already built and in use when the new laws were put into effect. The regulations explained how such buildings would be inspected, what kinds of improvements might be required, and how the changes made to comply with the regulations would be monitored and enforced. Any building built prior to the new law and not altered in the time since is an example of one covered under this second branch. 19. The major merit of the fire safety law with respect to buildings in use is that it made the regulation of fire safety with respect to the buildings themselves consistent throughout the country. A fixed set of requirements for certification – use of the premises, means of escape, fire-fighting provisions, and detection and warning systems – was put in place, which helped to eliminate confusion and inconsistent enforcement. (Billington, Ferguson, & Copping, 2002, p. 44) There seem to be two possible defects in the law, however. First, there are a number of discretionary requirements which the fire authorities may impose for a particular building if they judge the circumstances warrant, such as maintenance of escape, warning, and fire-fighting systems, staff training, occupancy limits, and “any other precautions that may need to be observed”. (Billington, Ferguson, & Copping, 2002, p. 44) While this is not necessarily bad, the details of these discretionary requirements are not clearly spelled out, which could lead to confusion and inconsistent application of the rules. Second, building use and occupancy limits for certain types of premises – restaurants and clubs are good examples – are also covered by local government regulations apart from the fire safety law, and it is possible that they are not always in agreement with one another. 20. A reaction to fire test measures how a material reacts to heat, either in the form of direct flame or high temperatures, and measures how quickly the material ignites, how the flames spread, and the amount of heat energy the material produces. A fire resistance test measures how long a material can last before it ‘burns through’ when exposed to a fire. The difference between the two is that a reaction to fire test is used to determine how hazardous a material is, and whether or not it is safe to use in certain applications in a building. It is related to the fire resistance test, but considers how the material itself will add to the fire, which the fire resistance test does not. The fire resistance test measures how well the material maintains its strength and stops or slows the spread of fire and heat to protect the building and occupants. References Australia Fire and Emergency Service Authorities Council (AFAC). (2009) “Fire Development”. (Webpage) Available from: http://knowledgeweb.afac.com.au/ national_data__and__glossary/CFBT_glossary/fire_development. Billington, M.J., Ferguson, A., and Copping, A. (2002) Means of Escape from Fire. London: Wiley. Cheshire Fire and Rescue Services. (2006) “A brief guide to the Fire Safety Order 2005”. Available from: http://www.cheshirefire.co.uk/Assets/business%20safety/rro_guide.pdf. Chu, G., Sun, J., Sun, Z., Chen, T., and Chen, X. (2001) “Quantitative Risk Assessment for Occupant Evacuation in Building Fires”. Progress in Safety Science and Technology, vol. 1. Available from: http://74.125.153.132/search?q=cache:6tG9-6cWA50J:lib.hpu.edu.cn/comp_meeting/PROGRESS%2520IN%2520SAFETY%2520SCIENCE%2520AND%2520TECHNOLOGY%2520VOL.V1/0351.doc+5+occupant+characteristics&cd=8&hl=en&ct=clnk. National Fire Protection Association (NFPA). (2005) User’s Manual for NFPA 921, 2nd Edition. Boston: Jones & Bartlett Publishers. Proulx, G. (2007) “Human Behaviour - How efficient are modelling systems?” Means of Escape (online), 2007. Available from: http://www.means-of-escape.com/articles/100/human-behaviour-how-efficient-are-modelling-systems/. Rasbash, D., Ramachandran, G., and Kandola, B. (2004) Evaluation of Fire Safety. Hoboken, New Jersey: Wiley. Read More