【 Weak current College 】 fire detection at the design, construction, smoke management problems and solutions-Power By 【 China power house network 】

Building fire supervision audit management regulations "(Decree of 30), equipped with automatic fire-fighting facility construction project, completed in engineering, construction and installation units must entrust qualified building fire facilities detection unit tests to test the building fire safety facilities technical report. In recent years, through a number of high-rise buildings and key project of automatic fire detection, the discovery of these buildings in smoke control design, construction and choice of fire-fighting equipment, and so there are some common issues, summarized as follows: 1. Natural smoke 1.1 under the tall buildings design fire protection standard of section 8.2.2, "smoke stairs staircase, Elevator front room to open the window area should not be less than 2.00 square meters, with former room should not be less than 3.00 square". Because of this provision in the specification section, the smoke did not arouse the attention of architects, so detection with natural gas of high-rise buildings, the vast majority does not meet the standard requirements of fenestration area, at the same time, you can open the window for the sliding window, making the original enough to open the window area and small half. Recommends that designers will replace sliding window casement window, maximize the window area. 1.2 under the tall buildings design fire protection standard section 8.2.2, "rely on the exterior wall of smoke stairs within the five-storey window area can be opened and should not be less than 2.00 square". In the detection of high-rise buildings, although it can be opened window area can meet regulatory requirements, however, some smoke stairs can open Windows installation height too high, it is difficult to open, do not design window device, in the event of fire, was unable to successfully open the designer window, the hope of attracting attention. 2. mechanical pressurization smoke control system pressurized smoke machines is to protect evacuation channel not be smoke, protect evacuation system, is the focus of the fire detection. 2.1 under the tall buildings design fire protection standard section 8.3.1, "do not have conditions of natural smoke exhaust smoke fire stairs, elevator room or shared room, should be set before the independent mechanical pressurization for smoke control facilities". Table 1 is detected the building of pressurization system of air supply list. The architecture of pressurization system of air supply list table 1 building name nameplate air blowers type blowers m3/h pressurization parts measured air flow m3/h specification recommended values m3/h× Plaza XGX-№ 7XGX-№ 7230002300 smoke stairs staircase № 1 smoke № 2135772080716000 ~ 2000016000 ~ 20000 × Hotel XLF-2A 7.518662 smoke staircase 9679.316000 ~ 20000 × building 4-72-11 8C4-72-11 8C4-72-11 8C4-72-11 8C20968209681748717487 smoke stairs staircase J1 J2 combined smoke control room J3 smoke stairs staircase J43579544923437983790822000 ~ 2700022000 ~ 2700016000 ~ 2000016000 ~ 20000 × × building T35-11 № 79600 combined front room 3433.622000 ~ 27000 × × Mall 4-68 № 1025300 combined front room 2379022000 ~ 27000 × × Center 4-72-11 6A11040 combined front room 818022000 ~ 27000 × building DZ-№ 619600 smoke staircase 737425000 ~ 30000 × building, 4-68-68-№ 8C4-№ 8C4-68-68-№ 8C4-№ 8C15000320001500015000 combined front room JS1 smoke stairs staircase JS2 JS2 smoke smoke staircase JS22376642644203831873816000 ~ 2000022000 ~ 2700016000 ~ 2000022000 ~ 27000 from table 1, you can see mechanical pressurization system air supply volume detection value is small, its causes are the following: (1) design-time selection of fan air volume is small, the specification is recommended value, according to the heating and ventilation design guide differential pressure or flow method to determine. (2) detection of smoke control in high-rise building its mechanical duct are brick ducts, the inner surface of outstanding plaster, plaster or very rough, causing the system to reduce the air resistance increase. (3) from the selected device, actually measured air flow centrifugal fan and blower nameplate air approach or exceed, axial fan, diagonal fan or high-temperature exhaust fan actually measured air flow and the difference between the air blower nameplate. Designed to supply air system resistance calculation to determine the choice of model fan, its flow, pressure head must meet the design requirements. At the same time, the choice of fan to choose high-quality brand-name manufacturers to ensure that the blower fan pressure to meet the requirements. 2.2 under the tall buildings design fire protection standard article 8.3.7 stipulates that "the mechanical pressure blowers, except for the calculation of the total pressure most disadvantaged central pipe head loss, should have a Yu pressure, pressure value should meet the following requirements: smoke staircase to 40 ~ 50pa, front room, shared room, fire before the elevator room 25 ~ 30pa". From the detection of high-rise buildings, the measured values and norms require a far, in addition to individual buildings to meet the requirement, most buildings are relatively small, table 2 lists some architectural measured top pressure value. Smoke staircase, the former room top pressure value list table 2 building name detection sites measured values over pressure (pa) in the pressurised air outlet type × building combined with former room smoke 1 staircase stairs stairway in front room smoke 20 ~ 30 ~ 54 ~ 65 ~ 9 always way normally open way normally open way normally open ways sharing room before building x smoke 1 staircase stairs stairway in front room smoke 2 greater than 25 ~ 22 is greater than 25 ~ 10 normally closed vertical Venetian blinds-Venetian-vertical-normally closed louvers × × square combined with former room 1 room 227 ~ 4014 ~ 70 normally closed blinds normally closed blinds × × building combined with former Room 8 ~ 15 normally closedVenetian building combined with former room × 0 ~ 2.5 normally open blinds × × hotel combined with the former, 2 ~ 8 normally open air in front of rooms, combined with the impact room top pressure value is due mainly to the large amount of air leakage, the system's main air leakage areas are as follows: (1) before the Chamber pressurization Tuyere close changbishi loosely high-rise buildings installed changbishi Tuyere, from all parts of the country, its quality has a very different, there is no strict of Tuyere close, with the naked eye can see air valve in the slit is very big, some air valve can not be flexible switch, eight active shutters seven twist twisted, seriously affecting the positive pressure ventilation system to work properly. For example: × × building combined with total air before the Chamber to 23790m3/h in just opened a positive pressure air measured layer air to 6500 ~ 8500 m3/h, total air about 1/3, resulting in low residual pressure value. The building, since there is a problem on the linkage control, fire control center can only be linked to open compression could not be opened before the forced draft fan pressurization testing in interaction, diffusers, pressure blower is turned on, and a pressurized air is not turned on, then the fan is operating normally, the amount of its air leakage. (2) air duct is tight as mentioned above, duct are brick construction ducts, inner surface plastering some haven't, causing air leakage. (3) the former room open fire door of licenses under the heating ventilation design manual pressure value formula, pressurized air and fire doors effective air leakage area, in direct proportion to the amount of fire door, fireproof door leakage area is pressurized air is increasing, the number opened fire doors are pressurized air is increasing. In high-rise apartment buildings, such as its residential entrance door (class b fire door) will open in shared room, before inevitably increase the total effective area of air leakage. Increase in the number of open fire door, in this case, or by the code for the recommended air to select the amount of wind blowers is obviously much smaller, it will cause more than the value before the Chamber pressure is small. Therefore, in the same premise pressurized air, when air leakage area increase or open fire door number increases, the residual pressure value will decrease. × × Architecture combined with front room at the same time on the second floor of the pressurized air, measured over the former Chamber pressure value is + 14pa, when only one layer of pressurized air inlet opening, top pressure value rose to 37pa. In the same room in the basement of the building, since the fire before the door aperture is 20mm, the residual pressure value before the Chamber only 14pa. (4) combined with the former rooms normally opened louver in table 2, you can see, there are few high-rise buildings of the former room selection normally opened louver as pressurized air, while the pressure blower air flow and air outlet not always evaluated. Thus, the measured over his former room almost zero pressure value. (5) smoke staircases do not form a closed cylinder smoke staircase to the roof of the evacuation doors, building is not installed, construction and installation of an ordinary door, without door closer, does not automatically turn off, into the stairwell pressurized air, there is a big part of the from here to leak out, on the stairs of the pressure values have a significant impact. Also, some commercial and residential building, household for ventilation requirements, often used wood will fire door jam, this also affects the stairway top pressure value. 2.3 compression air speed too high pressure supply outlet size size affects air wind speed found in test, some buildings at design time, the pressure air select size is too small, combined with the smallest outlet before the Chamber to 400 × 400mm, smoke staircase louver minimum size 200 × 200mm, the number is very small, causing serious excess of air speed, also affected the entire pressurized air, increasing the system's resistance to reduce the total air. Summary of test experience, want to design mechanical pressurization system must take into consideration the amount of loss, leakage of air leakage coefficient is recommended in more than 30%. You should also ensure that there is sufficient air pressure fan to ensure total air meet the requirements of the residual pressure value. 3. set the mechanical smoke exhaust system parts in doctrine has been expressly provided, here no longer speak. In fire detection involves mainly underground garage, basement of high-rise buildings, underground shopping centre, the main problems encountered are as follows: 3.1 exhaust air volume and air volume are mechanical smoke extraction system, the biggest problem, table 3 shows the parts of the building exhaust air volume and air flow measurement values. The building exhaust and air supply list table 3 building name smoke exhaust and air supply and exhaust blower model, air blower nameplate air flow m3/h exhaust and air supply and exhaust air parts measured air flow m3/h memo × square YGX № 7YGX № 7YGX № 7YGX № 7YGX № 7YGX № 7YGX № 7YGX № 7YGX № 7YGX № 722439224392243922439224392243922439224392243922439 underground garage 208481250010927151851658714296909794391113292004-72-11 5.5A (air) 4-72-11 5.5A (air) 4-72-11 5.5A (air) 4-72-11 5.5A (air) 4-72-11 5.5A (air) 4-72-11 5.5A (air) 4-72-11 5.5A (air) 4-72-11 5.5A (air) 4-72-11 5.5A (air) 979097909790979097909790979097909790 underground garage 145501227712874116041224711416107031149111426 × × underground garage XPY № 7XPY № 7XPY № 7240002400024000 underground garage 806380638063 × × Center HTF № 6HTF № 61510215102 basement 1125211253 × mansion HTF № 725000 underground garage 14730 × × building XPY № 614302 underground garage 16704 table 3 measured air flow is the system through the air volume measurement after rectification, without modification, many systems are not used, mainly because of: exhaust duct inside the debris, smoke fire dampers not action, check valves,Equipped with a power supply problem, exhaust fan, there was an equal to several systems in epicenters, exhaust air base is zero, the exhaust system and complement the wind system is not tested, nor used. From table 3 that use high-temperature exhaust fan of axial-flow exhaust system and wind system, its system of smoke quantity is small, the majority of the measured amount of exhaust smoke than standard air volume is small, the effect on exhaust air volume at relatively small because there is a large smoke control system resistance, wind pipe finish, exhaust outlet dimension and quantity. 3.2 exhaust systems and wind system noise noise is the exhaust system of the second major problem. If the exhaust system is combined with the ventilation system, only used when the fire broke out, the noise is not much difference, but there are more than 80% of the exhaust system and normal ventilation system with a system, then the noise impact on the environment should not be underestimated. In addition, public gathering places in the underground, the noise is also directly affect fire emergency broadcasting and sound and light alarm function. Causing smoke exhaust system noise mainly choose fan model, vibration and smoke exhaust system and muffler, select fan model is very important, this high-temperature axial exhaust fan noise is too much, even if the high temperature axial exhaust fan is set in the engine exhaust, and a muffler, the noise it makes. After our inspection of an underground sauna Center, the smoke exhaust system and the ventilation system with a fan, air ducts and air inlet, exhaust fan models to 4-68, exhaust air volume 10C 27000m3/h. In order to reduce the normal ventilation noises, the rectification, to increase a frequency converter, the usual ventilation of air volume control in 3500 m3/h, after reconstruction after a 24-hour ventilation system, underground sauna Center fresh air, in a warm environment, almost no fan noise. In the fire, the fire control centre frequency to 50HZ, rated exhaust volume. This increases a frequency converter, costs increase ten thousand Yuan. Used frequency fan exhaust of underground shopping malls do (ventilation), or promising. 3.3 underground garage of the vents under the garage, garage, parking design fire protection standard, underground garage and exhaust volume by ACH not less than 6 times/time calculations, and 1/3 on a row, the row 2/3. Design Institute in the design of the underground garage, generally using exhaust system and the ventilation system used, therefore, in the flue gas conditions, you must cut off the bottom row 2/3 of the vents, turn on the horizontal main pipe exhaust air outlet on. The most effective cut off the exhaust pipes of the device is electrically operated valve or with remote operation capability fire damper, fire, the fire control centre to signal, quickly cut off bottom vents. But some design selection is without remote operation function in normal fire dampers, only 70 ℃ yirongpian, early in the fire, when the gas temperature is not reached 70 ℃, the outlet will not close, and off vents air is big, it will seriously affect the smoke flow, personnel or material evacuation caused a great impact. 3.4 duct check valve non-return valve in the exhaust system is more prevalent in the detection, found on the installation of wind pipe valve problems, cannot effectively play the role to check. (1) check valve stem should be horizontally, and is installed vertically, up or down the stem. (2) check again Rod weight is not installed on, and some heavy hammer adjustment is not good, so check the action in question. (3) check valve itself not on or off, it requests the manufacturer's attention. 4. smoke control system in accordance with the norms requirements linked control, mechanical pressurization smoke control system, smoke wind systems and air-conditioning systems should be incorporated into the fire control centre for automatic interlocking control. When a fire occurs, the fire control centre issued a directive to make mechanical smoke, mechanical exhaust system rapidly put into use, air-conditioning system quickly shut down in order to achieve the purpose of the disaster. Mechanical pressurization smoke control system 4.1 when the fire alarm smoke signal layer, after layer all opened fire linkage room of pressurized air, linkage on the pressure blower and fan for smoke stairway. Fire extinguished by fire control centre issued a directive to stop the operation of the pressure blower, and the reduction of pressure supply outlet. 4.2 mechanical exhaust system when the sense of smoke detectors and alarm, to open the exhaust vent, the linkage between the exhaust valve to close down the exhaust pipes on the electric air valve or fire dampers, and associated air valve, close the usual use of ventilation systems. At the same time, linkage on the vertical wall of smoke, exhaust fan and blower. When the exhaust system of smoke fire dampers (280 ° c) fuse, off the exhaust fan and blower. 4.3 air conditioning systems as one smoke detector alarm, fire protection control center can cut off the air conditioning power architecture. When the air conditioning system to air dry pipe fire valve installed on yirongpian fuse, power off the air conditioner fan interlock.