Overview of Building Fire Safety
Fire Fighting Systems and Equipment in Buildings
Fire Detection Alarm Systems and Equipment in Buildings
Smoke Hazard Management Systems
Visitors to Premises
Overview of Building Fire Safety
Building fire safety comprises a "package" which incorporates construction methods, mechanical and electrical devices, management practice and organised human response tailored to reduce the impact of fire upon the occupants, the building, its contents, the attending firefighters and any neighbouring property. In the context of building fire safety, fire impact is considered to be any threat to life and property caused by heat or smoke and may include adverse environmental impact from toxic products stored on the premises.
Building fire safety cannot be defined as a "single system", it relies upon a group of "sub systems" to form a complete "package". More often than not, if one of the "sub systems" is removed, the whole "package" will collapse and the occupants within the building will face an unacceptable risk in the event of outbreak of fire. For simplicity, the "package" can be broken down into nine principle "sub systems", comprising:
- occupant training and education
- means of escape from the building
- ignition potential
- fire load
- compartmentation and structural fire resistance
- firefighting systems
- fire detection, alarm and communication systems
- smoke management systems
- fire brigade response.
Occupant Training and Education
An essential part of any building fire safety system (probably the most important part) is training and education of the occupants in matters of fire safety. Every conceivable device that technology can devise can be placed in a building but if the occupants are ignorant of what a fire alarm sounds like, what are safe and unsafe work practices or where the exits are, then the devices will not achieve a fire safe building. All too often occupant training, fire drills and safe work practices (all required by the Work Health and Safety Act 2012) are overlooked or given only superficial attention. A management plan, addressing all of these facets together with what to do after a fire has been extinguished to minimise its consequential effect, is very necessary if the overall fire safety system is to be effective.
for further information see emergency procedures
Means of Escape from the Building
This is an essential part of the fire safety system. A safe, illuminated, well identified way out of the building is required in order that the building occupants can escape a fire (or other) emergency. Often more than one escape route is required so that occupants have an alternative exit if one cannot be reached because of smoke or fire. These exits must be kept clear at all times. Storage of materials in exits is a common hazard and security problems are often overcome by illegally locking fire escape doors which places the lives of the building occupants at risk if a fire occurs.
Refer to the South Australian Occupational Health Safety and Welfare Regulations of 1995, Division 2.6.1 Access and Egress and Australian Standard 1657, for Fixed Platforms, Walkways, Stairwells and Ladders.
Fire load is a term used to describe how much combustible material is contained in a building and usually applies to the building contents. If the fire load is minimised then fire impact will be reduced. It is the fire load and how it is arranged (eg. furniture layout) or, in the case of a storage area, how the combustible goods are stored which determines the rate of fire growth and, hence, the rate of heat release from the burning materials. A large log chopped up into kindling wood presents the same fire load as the whole log, however, the kindling will quickly burn, releasing all its heat in a short time whereas the whole log (if it can be ignited in the first instance) will take a long time to burn and release its heat. Storing combustible materials in separate piles with a space between each pile is one way to reduce the impact of a fire in its early stages (assuming that only one pile initially catches fire). This will also initially slow down the rate of fire spread (growth) in the stored materials because the fire will need to jump from pile to pile.
Ignition potential describes the likelihood of a fire starting. There is no ignition potential in a bare room with no building services or people in it. Introduce people and you have an ignition potential, especially if the people smoke. People also make mistakes (human error). People, gas / electrical services, combustible materials, flammable liquids and tools of trade generate an ignition potential. If a room were full of all these things and the occupant was a compulsive arsonist, we would consider the ignition potential to be extreme. If we reduce the ignition potential, we reduce the risk of a fire outbreak.
Compartmentation and Structural Fire Resistance
If the fire is contained within a room or space (known as a compartment) by the nature of its construction, its impact on other parts of the building will be minimised. Naturally the people in the compartment will need to get out before the fire effects them. A room of solid brick with no windows and a sturdy door would be a good fire compartment, because it would be difficult for the heat and smoke to escape. A room constructed of glass would be a poor fire and smoke compartment because, as the fire grows, heat would shatter the glass thus letting heat and smoke out and the fire to spread.
Compartmentation is a called a "PASSIVE" system (ie. just by being there it inhibits the spread of fire). It relies upon structural stability under fire conditions; the ability to withstand the effects of fire without collapse.
Fire Fighting Systems
Fire fighting systems are those which intervene in the fire growth process. Such systems can be used by trained occupants or attending firefighters and include a fire extinguisher, fire hose reel, or fire hydrant. Other systems may be automatic such as a fire sprinkler system. Automatic systems are considered to be superior, because they do not rely on people to manually operate them. Fire fighting systems are known as "DYNAMIC" systems because they do something; they actively intervene in the rate of fire growth.
The greater the extinguishing capability of the system and the earlier in the fire growth period it can be applied, the lower the fire impact, hence, the preference for sprinkler systems by most fire engineers and firefighting professionals.
Fire Detection Alarm and Evacuation Warning Systems
The simplest fire detection and alarm system is the residential smoke alarm now installed in most Australian homes. The smoke alarm alerts the building occupants that a fire has been detected. A fire detection system may, in addition to alerting occupants, automatically notify the fire brigade of the fire. If fire detection and alarm systems operate very early in the fire growth stage, building occupants may be able to extinguish a small fire.
An evacuation warning system may be activated by a fire detection or firefighting system or manually by a chief fire warden for other circumstances such as a bomb threat. Many evacuation warning systems also have an intercommunication system such as a phone system and/or a public address system which can be used to pass information to the building occupants and fire wardens, who will orchestrate an orderly evacuation, or move occupants to safer parts of the building.
Smoke Management Systems
In many buildings occupied by the public, especially large buildings such as shopping centres, smoke from a fire can spread and descend so as to block exits and make occupant escape difficult or, in the extreme, impossible. In such instances, the installation of a smoke management system, which will slow down the rate of smoke spread, is recommended. Such systems often involve exhausting the smoke at ceiling level where hot smoke will naturally collect due to its buoyancy (because it is hot it is lighter than the surrounding air). Other methods employ the opening of apertures in the roof or panels at high level in the walls of a building. Provided fresh air is allowed to naturally flow into the building below any smoke layer, these measures will permit the smoke to escape from the building rather than fill it up. Another way to stop smoke infiltrating from floor to floor in a multi-storey building is to pressurise the non-fire floors with fresh air at a pressure higher than that of the fire floor.
Fire Brigade Response
The sub system taken for granted and often overlooked is the fire brigade response (notification, dispatch and travel time to the fire scene). How effective this response will be in saving life and property depends on how long the fire will have been burning before they are notified, how long they will take to arrive, how fast the fire will grow, how much equipment they will bring with them and how much water will be available for firefighting. Generally, compared to metropolitan areas, the time taken to arrive in rural areas is longer, not as much equipment is initially available and water is often in limited supply. However, as time passes in both rural and metropolitan areas, more and more firefighters and equipment will arrive as resources are brought in from further afield. The NSW bush fires are an example of how distant resources can be mobilised for a big fire. Every state in Australia sent firefighters and equipment, and some came from New Zealand.
Many people believe the fire brigade will charge for attending a house fire. This is not the case. For bona-fide emergencies, the fire brigade does not charge.
Many people believe that living opposite a fire station means the fire brigade response time will be very short. Often this will be the case. However, as has happened many times, the local fire brigade may be out at another fire call meaning that resources have to be drawn from further away and that will take a lot longer.
For further discussion or advice on these issues, please contact the Community Safety Department.
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