【 Weak current College 】 tall buildings smoke fire safety measures for consideration---Power By 【 China power house network 】

Smoke control in high-rise building fire safety measures for consideration
Scientific and rational design of mechanical smoke extraction system for high-rise buildings are important, it means that the fire, the timely removal of harmful smoke, so that the evacuation. In the architectural design process, often find that some designers in the design of mechanical smoke extraction system, mechanical smoke extraction system works and the role of a lack of awareness, understanding of the specification is very fuzzy, and specification requirements have greater access to design methods and controls methods, resulting in fire smoke system was unable to play its proper role. The following author mechanical smoke extraction system for fire safety technical measures do some brief summary, for reference purposes only.
First, you should set mechanical exhaust system parts
A tall and building height exceeding 32m II class levels of the following four parts should be set mechanical smoke extraction facilities:
1. no direct natural ventilation and longer than the inner passages or 20m directly on the natural ventilation but longer than the inner passages 60m; for direct natural ventilation length 20m ~ 60m within the aisle between, to open the window area is greater than 2% of the sidewalk area, natural smoke exhaust requirements without the need for mechanical smoke extraction, consideration should be given set mechanical smoke extraction facilities.
2. more than 100m2 and often some people stay or fuel more ground and no window and set a fixed window room; an area of less than 100m2 room and corridors between and among of partition should meet the specifications, you should press the room additive area calculation.
3. each room has a total area of more than one room area 200m2 or exceed 50m2, and often someone stay or fuel more nor use of Windows for natural gas wells in the basement.
4. do not have natural smoke conditions or headroom above the Atrium 12m.
Second, with regard to the exhaust fan exhaust of
When the smoke exhaust system with a smoke partition should less than 6 m in height exhaust or not divided smoke partition room exhaust fan exhaust volume should be per square metre area not less than 60m3/h. With two or more smoke partition exhaust, the maximum preventing smoke partition area per square meter than 120m3/h.
Atrium of its volume should be multiplied by the number of air changes per hour, when the volume is less than the amount of time, exhaust 17000m3 per hour calculated by ventilation 6 times, when the volume is greater than 17000m3, hour 4 times by ventilation.
Atrium is calculated as follows: If the volume is 16000m3 Atrium, exhaust fan and exhaust volume should be greater than (16000m3× 6th/h) 96000m3/h; the Atrium volume-18000m3, then exhaust volume should be greater than (18000m3× 4th/h) 72000m3/h.
Here you need to note that the smoke was modelled on the atrium of foreign data bases, taking into account the volume more than 17000m3 Atrium, while larger, fire load relative may be larger, but their storage capacity relative increase tobacco, therefore reducing the ACH. But I think that down in 17000m3, it should also be according to the specific factual circumstances do specific analysis, so as not to increase investment, resulting in unnecessary waste.
3. exhaust fan settings
Exhaust fan should be located in separate air in the engine room, the engine room fire resistance of partition should not be less than 2h, floor should not be less than 1.5h. Exhaust fan in room partition wall inlet pipe should be set to automatically turn off when 280oC of smoke fire dampers.
IV. the settings of the exhaust air hose
Exhaust air pipe should not cross the horizontal partition. Two fire partitions share a set of exhaust systems, engine room exhaust ventilation should be located in two neighbouring fire partitions to ensure that the firewall needs to pass through the firewall but still in the air duct fire compartment as possible short and should be set smoke fire dampers and do the corresponding fire protection measures. Vertical through layers of vertical duct should be set within the pipe shaft or concrete duct.
Take two and over smoke exhaust system partition, you should set up branches on each smoke partitions on exhaust, branch pipes should be set to automatically turn off when 280oC of smoke fire dampers. If no partition wall with large Bay in the middle of the building, its roof is equipped with a navigation over the deep beam 0.5m divided smoke partitions, located in the beam of the primary air branch pipes should be set on each smoke partition exhaust, technically you can solve the problem of exhaust port settings.
Exhaust air pipe should be fire-resistant performance of noncombustible materials. Suspended ceiling in the exhaust duct outer surface should be the package like mineral wool, glass wool, rock wool, aluminum and other non-combustible materials for thermal insulation, exhaust duct outer surface and a distance of combustible component should not be less than 0.15m. Exhaust air pipe through the smoke wall, non-burning materials such as cement mortar will close the gap between the two is filled.
Exhaust air pipe end flue gas discharge should be used with the same plate or fire performance of materials, should be considered when setting the discharge of smoke cannot directly to blow the fire risk in other parts of the building, not close to the ventilation or air conditioning systems and other equipment of suction, cannot affect the evacuation and fire fighting, when located outdoors should prevent rain, pest birds, and other intrusive damage.
5. exhaust port settings
When using the wall or vertical wall of smoke and other dividing smoke partitions, each partition should be setup for smoke exhaust port, each exhaust system is equipped with exhaust port number should not be more than 30, to reduce the air leakage rate on the effects of smoke.
Exhaust outlet should be located in the Centre of smoke partition, to the smoke partition farthest point level should not exceed 30m, and should be located in the ceiling or near the ceiling. Generally smoke exhaust outlet should be located away from the ceiling height in 0.8 m, but for a ceiling height of over 3 m building, exhaust outlet can be located at the height above the ground 2.1m. NET height over the Atrium 12m, vertical exhaust vents should be segmentation settings.
The dimensions of the exhaust outlet, flue gas through smoke extraction of effective cross-section of speed not less than 10m/seconds to calculate area generally should not be less than 0.04m2.
Exhaust vents should be set manually and since the sceneFixed opening device, and fire control equipment linkage of automatic opening device and removing Control Center remote manual open device. Exhaust vents should be closed, in peacetime and vents the merge settings for mechanical smoke extraction system, alarm, energy control center should be able to automatically close the non-fire smoke partition of exhaust port.
6. mechanical smoke extraction system control
When equipped with fire alarm system and smoke exhaust system linkage, a smoke partition of smoke (temperature sensor) detector, alarming energy control center control device to automatically open the smoke exhaust port within the partition (or exhaust mouth scene smoke chain automatically turned on), start with this smoke partition-related activities-exhaust fan and smoke vertical wall, and the feedback signals back to the fire control equipment.
It should be noted:
1. start of exhaust fan should be determined by the system in any action control exhaust vents, and fire control equipment should be remote manual direct control function. We have talked about manual direct control, which is the not the software programming and bus transport hardware circuit control, computer-on-disk, was clearly outside the direct control mode manually.
2. fire control equipment can only open fire smoke exhaust port within the partition, the partition other smoke still exhaust vents should be closed. But smoke spread to adjacent smoke partition, a partition adjacent smoke exhaust vents should be able to smoke to exhaust the chain opened automatically. Unframed smoke partition room all exhaust vents should be opened, the smoke is equal to the amount of exhaust smoke.
3. fan the former entrance smoke fire valve when the gas temperature reached 280oc automatically shut down, the exhaust fan should be linked to stop running.
4. smoke partition or partition smoke partition of the rooms have multiple exhaust port, in order to prevent the exhaust vents open at the same time action current is too large, you can use a serial connection to relay their mutual conspiracy in the form of dynamic open adjacent control exhaust vents, and the last action of the exhaust port output signal sent to the fire control equipment.
The only responsible smoke partition or a division of smoke partition room of mechanical smoke extraction system, design is often chosen without control normally open shutters-exhaust vents, and installed in the exhaust fan in front of the smoke fire dampers in place of this should close the exhaust port. This valve has an exhaust port field manual, alarm and remote control functions, usually shut down, fire alarm, fire control equipment which, at the same time opens the linkage starts to smoke exhaust fan. When the gas temperature reached 280 ° c are automatically turned off, and linkage closes the exhaust fan. Its action signals are back down to the fire control equipment.
In a outlet exhaust ports and merge settings for mechanical smoke extraction system, due to the usual exhaust and fire smoke exhaust system, compatible with a common set of air pipe, exhaust vents and outlet control. At this point there are two situations:
1. the exhaust outlet from the outlet, exhaust vents set normally closed does not participate in the exhaust duct work, on the other is equipped with exhaust pipes are connected with normally open vents, exhaust pipes and competent connection parts equipped with fire protection function of the electric valve. Fire alarm, fire smoke exhaust port within the district, at the same time, turn off the system on all of the exhaust pipes of the electric valve (that is, close any outlet).
2. exhaust port usually always, as the exhaust vents to assume tasks, known as the exhaust vents. Fire alarm, the non-fire smoke partitions within the exhaust vents all automatically after receiving the signal, and fire off smoke partitions within the exhaust gas outlet does not act as smoke extraction tasks. This control is more complex, trial and ensure safety.
Finally it is worth noting that, as the exhaust system of electrical circuitry, shall take appropriate measures to ensure the safety and security, so as to avoid causing system crashes.