Flashcards
Fire and Building Services No.2
Cards in this deck (26)
- 1What are the services to rescue (use of services to fight fire and aid evacuation0?- Detection
- Extinguishers and hose reels
- Sprinklers
- Hydrants, rising mains and fire fighting lobbies
- Fire fighting stairs and lifts
- Pressurisation
- Emergency lighting - 2Detection: How is it usually detected? What is the best protection?Fire is most difficult to detect during initial stages, often only noticed if person in close proximity. Once fire has taken hold it is easy to spot the more difficult to extinguish. Best protection is afforded if buyers can be found early, simple systems are manual, operated by building occupants breaking a glass cover and pressing a button to sound an alarm.
- 3Detection: Best detection? Will this reduce incidents? What do they make use of?Detection systems that do this automatically the best protection. Will not reduce incidents of fire but reduces damage through reducing delay two detecting and combating. Commonly make use of smoke detectors but good practice to use varity - devices which detect heat and radiation are also available. Smoke often most copious product in early stages so easy to detect. One of the most dangerous and can interfere with evacuation building. E.g. if visibility dropped below 10 m people reluctant to use escape route sound audible alarm, trigger ancillary e.g. fire dampers, fan motors, emergency electricity supplies, and alert fire services.
- 4Detection: Different levels of protection? Common zone systems? How are zones organised?Different levels of protection can be provided ranging from positioning detectors throughout the building, to protecting particularly hazardous areas to having them only on escape routes. It is common to zone the system to allow easy identification of where the problem has occurred and a control board is often supplied in the building lobby for this purpose. Zones are typically compartmentalised areas and escape routes.
- 5Extinguishers and hose reels: What are the first form of firefighting? What do they consist of?Portable extinguishers and hose reels form part of first aid firefighting system. Hose reels consist of water supply with control valve connected to a drum hoarding rubber hose with nozzle and cock.
- 6Extinguishers and hose reels: How often are they provided? Length?One hose must be provided every 800m2 of floor space and it must be sited in a prominent and accessible position such that it is capable of reaching within 6m of each part of the space served. The maximum length of the hose is 45m and it requires a water supply of a minimum of 24l/s at sufficient pressure to produce a 6m jet.
- 7Sprinklers: What does the system consist of?A sprinkler system consists of a water supply and one or more installations. Installations consist of a main control valve and a pipe array fitted with spray heads at roof or ceiling level.
- 8Sprinklers: How does the system work? When do they activate? What does this cause?The system operates at a pre-determined temperature and it is usual, therefore, for only the sprinkler heads in the vicinity of the fire to operate. These are activated at about 70C by the expansion of a fluid contained in a small glass bulb. This causes the bulb to rupture opening the sprinkler head in the process. An alternative arrangement is a fusible link that melts and opens the sprinkler head.
- 9Sprinklers: What does flow of water initiate? What may the system be linked to? What information could it provide?Flow of water through the pipework initiates an alarm either by operating a turbine or by tripping a sensor designed to detect flow equal to one or more sprinkler heads. The sprinkler alarm may link in with the general building fire alarm system and activate other fire fighting systems. In addition it should provide information on a control board identifying where the problem has occurred.
- 10Sprinklers: What are the 3 main types of systems?- Wet pipe systems where the pipes are maintained full of water. This is the preferred system
but is no use if ambient temperatures drop below 0C (pipes may freeze either bursting or preventing flow in the event of a fire) or rise above 70C (the sprinkler heads will open and flood the building).
Wet and dry pipe systems where the pipe is filled with water during the summer months and with compressed air in winter.
- Dry pipe systems which are filled with compressed air and are only used where the two previous systems are unsuitable e.g., in cold storage rooms. - 11Sprinklers: Why must care be exercised?Care has to be exercised when selecting a water supply for the system in order to ensure it is suitable for the height of the building and the nature of the hazard contained.
- 12Hydrants, rising mains and fire fighting lobbies: What do they contain? Where are they provided?Hydrants contain a valve and an outlet connection to form a water supply main. They are often provided near buildings in areas that are not at risk from debris falling as a result of the fire.
- 13Hydrants, rising mains and fire fighting lobbies: What is put in place to assist fighting fires? What does this contain? What do they permit?A rising main is a pipe system designed to assist in the fighting of fires. The rising main is provided with landing valves positioned either in stairways or in vented lobbies next to stairways. These permit the fire fighting services to connect a hose to the water main and fight the fire.
- 14Hydrants, rising mains and fire fighting lobbies: How are they similar to sprinkler systems?Floors? How are dry systems fed?As with sprinkler systems, rising mains can be of either the wet or dry type and are required in any building where the floor level is above 18m. If there are floors more than 60m above ground level the riser must be of the wet type (in order to prevent delays in water reaching the top). Dry systems are fed from a hydrant via a fire pump. Wet systems are usually fed using an automatic pumping system.
- 15Fire fighting stairs and lifts: Why are they needed? When is this provided?Fire fighting lifts are required to transport fire fighting personnel and their equipment quickly to floors high above ground level, thus preserving their energy for fighting the fire. This provision is required in buildings with stories more than 18m above ground level where the lift forms part of a firefighting shaft, which in addition contains a stair and a firefighting lobby.
- 16Fire fighting stairs and lifts: What do the stairs provide? What does the lobby provide?The stair provides communication over short distances (fire fighters often take the lift to the floor below the fire) and a means of retreat should the lift fail. The lobby protects the fire fighting lift and stair from the full effects of the fire and acts as a bridgehead from which the fire may be attacked.
- 17Fire fighting stairs and lifts: How are they different form normal lifts? How is the plant room connected?Firefighting lifts differ from normal passenger lifts in that they are designed to remain in operation during a fire. The plant room is positioned within the firefighting shaft and the running gear is connected to an emergency electrical supply to maintain operation should the normal supply fail.
- 18Fire fighting stairs and lifts: What else are protected? What about the car?In addition the electrical systems are protected from the effects of water which is used to fight the fire. The car itself is made from incombustible material, contains a trap door as a means of escape and a microphone and loudspeaker to summon assistance.
- 19Pressurisation: What is it and why is it needed?It is important that escape routes are kept clear of smoke to permit safe evacuation of the building’s occupants in the event of a fire. Compartmentalisation is rarely 100% effective at containing a fire and smoke will force itself through cracks and around doors etc. Injecting fresh air into staircases, lobbies and corridors to raise their pressure to about 50Pa above that of adjacent areas in a building can help to prevent smoke ingress.
- 20Pressurisation: Why is it provided? What is it capable of?The system provided to keep escape routes free from smoke should be simple, reliable and capable of providing the required pressurisation soon after the fire has been detected. It should be capable of being initiated by the smoke/fire detector system, a sprinkler system or manually.
- 21Pressurisation: When should the fan run? Is the system simple?The fan should run from a protected electrical supply and should suck in air from a part of the building that is not prone to smoke contamination from either the outlet of the normal ventilation system or as the result of smoke escaping via the windows of the building. This system can be very simple as the supply air does not require conditioning and the fan does not require a silencer.
- 22Pressurisation: Where is the air taken to? What about the air from the stairwell?The air from the fan should be transported using a duct housed in a protected shaft with outlets into stairwells no more than 3 stories apart. The air supplied to the stairwell should then be allowed to exit at designated points distant from escape routes so that any vented smoke does not hinder evacuation.
- 23Pressurisation: What is it important to consider? What does this encourage?It is important that consideration is given to how the pressurisation system interacts with the air supply systems in the compartmentalised spaces. These should be laid out so as to encourage an airflow pattern that is directed away from escape routes.
- 24Pressurisation: What happens once the pressurisation system is activated? In addition?Once the pressurisation system has been initiated the normal system should halt all re-circulation of air and vent the exhaust via a specially designed damper in the building envelope. In addition the normal supply air will often be halted and the extract, if designed to run in the event of a fire, will be left running.
- 25Emergency lighting: Why is needed? When is it needed? Where is it needed? In addition?It is necessary to provide a system of emergency lighting powered using batteries or a protected circuit connected to a battery system or emergency generator. This should operate when the normal lighting system fails and permit safe movement of occupants along escape routes. This will entail lighting the areas around exit doors, near safety and fire fighting equipment and stairs. In addition this system will assist emergency services making their way through the building to find casualties and fight the fire.
- 26Give a summary on fire?It is necessary to sound a note of caution concerning the design of buildings for fire. It is a very complicated process with numerous systems which must be capable of acting both individually and in combination with other systems. The consequences of getting the design of a single element wrong can result in massive loss of life and property. For this reason it is vital to consult with fire fighting services, Building Control and any other relevant bodies at an early stage in the design process.
Information
- Description
- Architectural Engineering Flashcards on Fire and Building Services No.2, created by Alice K on 26/10/2019.
- Created by
- Alice K
- Views
- 0
- Rating