Smoke extraction in buildings

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  • In your file: you mention galvanized steel duct with additional protection for fire resisting smoke extract ducts. What's about ductwork must be protection itselt?
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  • Extraction systems play a crucial role in fire protection, and may even be the difference between life and death: Often it is not the flames that injure or kill people, but the resultant smoke. Thick smoke can obscure fire exits, while smoke inhalation can damage body tissue and lead to asphyxiation. Visit our website for more information: http://www.curvent.co.za/extraction-systems/
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  • Toxicity depends upon the material which is under fire.Pyrolysis- Thermochemicaldecomposition of organics without oxygen.
  • The given time line is for a 2 storey house –this is just a time line representing the different steps from fire commence to the fire fighter arrivalNFPA-types of firesA,-from paper, cloth etcB,-from gasoline ..C,-electrical equipmentsD,-from metalsK- kitchen containing natural oilsOther classifications are also there.Borosilicate glass-fire resistant glazing Fire resistant wall-gypsum board partitions, reinforced concrete
  • ->not practical to design based on any fire size->smoke developed depends on room size,firesize,material combustibility->smoke extraction rate –fan size,temperature rating for fans,incoming air resistance of make up air.->extract fans are the principal mechanical means of smoke and fume removal->vent size,escapetime,sprinklers,fans,fire and smoke dampers,smoke curtains,->stack effect-movement of air due to the buoyancy,temperature effect and pressure difference-chimney effect-dP=Cah(1/T0-1/T1)-during heating season,the hot air in the room rise high,and make the cold air enter through the lower openings
  • - Sprinkler-each closed head sprinkler is held closed by heat sensitive glass bulb or two part metal link held together with fusible alloy -in a standard wet pipe sprinkler system,each sprinklers operate indipendantly- Sprinklers will be in to the action 1-4 minutes,for fire fighters it will requre minimum 5 minutes to reach and 10 minutes to fix the arrangemets.
  • -low amount of oxygen-affect fire fighting-corrosive nature of hcl-attack structural steel and rcc-weakens the construction-treatment-avail oxygen
  • Reduce property loss
  • Extreme care for avoiding mixingHole-if smoke is tried to be extracted through 1 opening only ,then a hole like shape occurs just below the extraction point and thorugh this more fresh air than the smoke will be lostMany extraction points-evenly placed
  • -don’t push or suck-just carry smoke from the room to outside area.
  • -all fire starts small and grow larger-difficult to select a smoke extraction system for all fire sizes-
  • -fire cant be represented by a single source-frequent strategy is to relate design fire size to sprinkler operation-normal combustibles rarely exceeds .5MW/m2-sprinklers are placed according to max fire size area(below)-
  • Smoke production depends on fire size and plume heightFor fire fighter access only-2 and 2.5 respectivelyProperty protectionPrevents to adjacent areasSmoke curtains
  • Half for the multi storey buildingPermanent smoke curtains- glazed smoke screenRetractable smoke screen-drops when alarm operatesMust extend below the base of smoke layer
  • 300 deg is usually expectedBut will be less if sprinklers are thereSpecific heat of smoke=1kj/kg
  • When smoke being extracted from 2 or more interconnected storeys ,the highest smoke temperature will occur with fire on highest storey
  • If natural inlet is given-like doors and windows , should open automatically when extract system starts workingIf not possible to maintain below 1.5 m- use smoke curtains , horizontal shields.Curtains or shafts are used not to make mix of fresh air with the smoke
  • Standard galvanized steel ductwork can withstand up to 400 deg provided no aluminium rivets and combustible seals-dampers should be within the thicknes-the fsd should be operated not only with temp but also with smoke detectionHVCA-heating and ventilation contractors association
  • Most cases fire resistance to internal and external fire are required-but some cases its not required.Fire resistance of the duct =fire resistance of wall through which it passes. But in some cases eg: here the possibility of getting any fire in the corridor is very less ,so the duct at that place need not be fire resistant to external fire.
  • BS 476.part 24:1987-another requirement is that duct must be able to retain 75% of its cs area throughout the fireStabilitySaid to have violated stability criteria,if a frdw exposed to external fire (duct A) collapses in furnaceSaid to have violated s .if either length of duct A or duct B exposed to internal and external fire within furnace collapses outside the furnaceIntegrityCracks ,holes or other types of openings through which smoke leaksInsulationWhen temperature rise above initial temperature on the unexposed surface of duct exceeds 1, 140 deg as an avg value 2, 180 deg as maximum valueThen it fails to keep its insulation property
  • Buckling-when smoke goes –expansion occur
  • HangersSteel hangers with more than 2000mm of length must be insulated with fire resisting material to resisting expansion and catastrophic failure
  • Evacuation time is >60 minSmoke must not spreadNormal hvac system can be modified to smoke extract
  • Fsd-leakage-for exhaust-I,IISupply-III,IVHigh wind pressure-break windows,use sprinklers
  • Here the main function of smoke extraction system is property protection and fire fighting assistance
  • Design fire size is based on 1 carIf sprinkled-1.5 MwUnsprinkled-3 MwGenerally both inlets and outlets are ductedInlets should be at low level and outlet at high levelMin 10 ach If duct 500mm there is no fire chance –insulation requirement may be given with some flexibility.
  • Separated from all other floors except at the base
  • 1,if it provides both integrity and insulation-no other action is needed2, if provides only integrity, fire protection systems should be designed-temp should not go beyond -300 deg, sprinklersNon combustible non fire resistant-Building should be sprinkled,300 deg or failure temperature of glass whichever is lower, negative atrium pressure can be given to avoid the movement of smoke to floors
  • If the people are acquaintant with the then normal single stage evacuation can be provided,If not aquaintant ,then smoke base should not come beyond the enclosure for a specific time
  • Sprinkler systems must be providedMust be designed in a way that no untenable should occur ,atleast for the expected evacuation timeWaiting areas-which is pressurised-can be used for other purposes when there is no fire, provided there should be having enough space for people to enter to that place when fire happens.
  • Mall area are the escape areas
  • Not effective for more than 2 stories
  • If area of shop greater than 3000m sq, and 1000 m sq,then independent extraction is better
  • Temp stratification-happens if the temp of smoke just below the ceiling is more hotter than the floor smoke –it happens in summer-due to this the smoke will not be able to reach fastly to the top where the detectors are placed. so this time lag will create a situation of spreading of smoke to more areas before the fire alarm starts.Cooling effect- is the process of mixing of smoke with more fresh air and settling down by the loss of buoyancy when the height or area of reservoir is more than that of allowed value.
  • -deals with life safety-design and performance standards-IRI-insures properties based on information manual deals with belt driven smoke exhaust fans-sbcci-us +other foreign countries-building codes-NFPA-3 functional categories 1-improves the methods of fire protection ,elctrical safety and other safeties 2-obtains and circulates information on these subjects 3-secures cooperation of its members and public in establishing proper safeguards against loss of life and -National building code of India(NBC)-2005-London District Surveyors Association(LDSA)
  • Smoke extraction in buildings

    1. 1. SMOKE EXTRACTION IN BUILDINGS<br /> Presented by<br />VysakhManohar<br />GATE-Chennai<br />Tuesday, June 07, 2011<br />1<br />Smoke Extraction In Buildings<br />
    2. 2. INTRODUCTION<br />Effective smoke extraction in buildings has been one of the inevitable considerations in the building design as the number of buildings and the concern of people about the regular fire accidents in buildings are increasing much.<br />This presentation includes a brief description about the different design consideration principles and methods to be taken care for the effective heat extraction in different types of buildings . <br />Tuesday, June 07, 2011<br />2<br />Smoke Extraction In Buildings<br />
    3. 3. What is smoke?<br />By product of combustion or pyrolysis .<br />Mixture of liquid , solid particulate matter and gaseous products.<br />It is a cocktail of carbon monoxide, carbon dioxide ,HCL and HCN<br />Tuesday, June 07, 2011<br />3<br />Smoke Extraction In Buildings<br />
    4. 4. FIRE TIME LINE<br />00.00- Household is asleep<br />00.30- Fire ignites and grows in downstairs<br />1.04- Fire spreads and smoke begins to fill<br />In the room.<br />1.35- Smoke layer descends rapidly and<br /> temperature exceeds 88 deg<br />1.50 – Smoke detector sounds an alarm.<br />2.30- Temperature becomes 205 deg<br />2.48- smoke pours into other rooms<br />Tuesday, June 07, 2011<br />4<br />Smoke Extraction In Buildings<br />
    5. 5. 3.03-Temperature in the room becomes more than 260 deg<br />3.20-upstairs,corridors,all the rooms are filled with smoke<br />3.41- flashover occurs , temperature becomes 760 deg <br />3.50 –Two minutes after the alarm sound, only the second exit will be the way out<br />4.33- Flames will be apparent from the outside , the first evidence of fire visible from outside.<br />Tuesday, June 07, 2011<br />5<br />Smoke Extraction In Buildings<br />
    6. 6. Will follow similar scenario in other location<br />The variations will be based on<br /> 1-fire size<br /> 2-size of building<br /> 3-flammable materials in the building<br /> 4-alarm systems<br /> 5-safety measures available<br />Tuesday, June 07, 2011<br />6<br />Smoke Extraction In Buildings<br />
    7. 7. GETTING THE DESIGN RIGHT FROM THE BEGINNING<br />Factors affected<br /> Design fire size<br /> Stack and wind effects<br />Temperature effect of fire<br /> HVAC and ventilation systems<br />Climate<br /> Expansion of ducts<br />
    8. 8. COMMON SAFETY METHODS<br />Use sprinklers<br />Smoke curtains<br />HVAC system incorporating F & S dampers.<br />Extraction fans<br />Alarm systems<br />Pressurisation<br />Tuesday, June 07, 2011<br />8<br />Smoke Extraction In Buildings<br />
    9. 9. HAZARDS OF DANGEROUS SMOKE<br />Impair visibility<br />Coughing,nausea,vomiting<br />Generation of high temperature<br />Irritation and respiratory problems<br />Bronchospasms and hypoxia<br />Inflict death if it contains dangerous gases<br />Even low concentration of CO can cause diminished coordination and increased disorientation<br />Amount of oxygen is reduced- suffocation<br />Exacerbate corrosive nature of HCL<br />Tuesday, June 07, 2011<br />9<br />Smoke Extraction In Buildings<br />
    10. 10. Smoke Pathways<br />Air and service ducts connecting floors<br />HVAC/ventilation systems<br />Extract duct systems<br />Gaps between wall and floor constructions<br />Stairwells<br />Lift shafts<br />Tuesday, June 07, 2011<br />10<br />Smoke Extraction In Buildings<br />
    11. 11. Need of smoke extraction<br /> for life safety and reducing property loss<br /> for fire fighter access<br />To clear smoke after a fire –smoke purging<br />Tuesday, June 07, 2011<br />11<br />Smoke Extraction In Buildings<br />
    12. 12. Smoke extraction design objectives<br />Effective protection of building occupants by maintaining tenable conditions on egress systems.<br />Reliable and functional fire fighting controls used by firefighters to increase visibility and reduce heat exposure.<br />Tuesday, June 07, 2011<br />12<br />Smoke Extraction In Buildings<br />
    13. 13. Make up air routes<br />External doors<br />Louvers in wall or roof<br />Central air plant configured to supply air<br />From adjacent unaffected areas<br />->avoid mixing of smoke and make up air<br />->extraction points-avoid creation of “hole”<br />Tuesday, June 07, 2011<br />13<br />Smoke Extraction In Buildings<br />
    14. 14. Smoke Production and movement<br />Amount of smoke produced is dependent on size of fire<br />Path through which it goes<br />Plume height<br />Tuesday, June 07, 2011<br />14<br />Smoke Extraction In Buildings<br />
    15. 15. Fundamental design factors<br />Design fire size<br />Smoke layer depth<br />Identify smoke reservoirs<br />Calculate smoke volume and temperature<br />Minimum number of extract points<br />Vent or fan size and fan temperature rating<br />Inlet air<br />Duct work<br />Tuesday, June 07, 2011<br />15<br />Smoke Extraction In Buildings<br />
    16. 16. Design fire size<br />Fire starts small and becomes large<br />Vent area=2.5 % of floor area-otherwise mechanical<br />6 ac/hour is used often<br />Design fire size is greatly dependent on building contents.<br />Based on the largest fire source<br />Cannot surely withstand post flash over conditions<br />Tuesday, June 07, 2011<br />16<br />Smoke Extraction In Buildings<br />
    17. 17. Heat output of fire<br />National bureau of standards in USA<br />Based on time-<br /> safe escape time<br /> brigade response time<br />Tuesday, June 07, 2011<br />17<br />Smoke Extraction In Buildings<br />
    18. 18. Acceptable smoke layer depth<br />Smoke layer base should be above the people<br />2.5 m-single storey<br />3 m - upper storey of 2 storey<br />Tuesday, June 07, 2011<br />18<br />Smoke Extraction In Buildings<br />
    19. 19. Smoke reservoirs<br />If smoke is held in a too large reservoir-lose buoyancy<br />2000 m^2 - natural extraction<br />2600 m^2 -powered extraction<br />Smoke curtains can be used to reduce horizontal spread<br />Tuesday, June 07, 2011<br />19<br />Smoke Extraction In Buildings<br />
    20. 20. Tuesday, June 07, 2011<br />20<br />Smoke Extraction In Buildings<br />
    21. 21. Smoke- volume, mass flow rate and temperature<br />T=Q/m cp<br />1/3 is gained by building structure<br />Tuesday, June 07, 2011<br />21<br />Smoke Extraction In Buildings<br />
    22. 22. Minimum no of extract points<br />Mcr is not exceeded<br />No smoke need to travel more than 30 m to extraction point<br />Tuesday, June 07, 2011<br />22<br />Smoke Extraction In Buildings<br />
    23. 23. Inlet air<br />To make up the smoky gases<br />At least 1.5m beneath smoke layer<br />If natural inlet is given<br />Inlets should be away from the outlets<br />Inlet velocity should be less than 3 m/s<br />Tuesday, June 07, 2011<br />23<br />Smoke Extraction In Buildings<br />
    24. 24. Tuesday, June 07, 2011<br />24<br />Smoke Extraction In Buildings<br />
    25. 25. Ductwork<br />Must be able to withstand anticipated temp- From the formula<br />HVCA specification DW144<br />For sprinkled buildings<br />To limit fire spread<br /> -fire protection of steel ducts<br /> -construct from proprietary material<br /> - use fire and smoke dampers<br />Tuesday, June 07, 2011<br />25<br />Smoke Extraction In Buildings<br />
    26. 26. Fire resisting requirement of ductwork<br />To prevent fire inside one duct to breaking out to other compartment.<br />To prevent fire from outside enter into duct and then enter another fire compartment<br />To prevent fire from outside enter into duct and the break out into other compartment<br />Tuesday, June 07, 2011<br />26<br />Smoke Extraction In Buildings<br />
    27. 27. Tuesday, June 07, 2011<br />27<br />Smoke Extraction In Buildings<br />
    28. 28. Tuesday, June 07, 2011<br />28<br />Smoke Extraction In Buildings<br />
    29. 29. Performance criteria for fire resisting duct work<br />Stability<br />Integrity<br />Insulation<br />Tuesday, June 07, 2011<br />29<br />Smoke Extraction In Buildings<br />
    30. 30. Other things to be noted<br />Duct must be able to retain at least 75% of its size after the smoke removal.<br />Sound or thermal insulation should not be raised to ignition temperature.<br />Fire stopping seals should be used<br />Buckling or collapse.<br />Tuesday, June 07, 2011<br />30<br />Smoke Extraction In Buildings<br />
    31. 31. Construction of fire resisting smoke extract ducts <br /> a) galvanized steel duct with additional<br /> protection<br /> b) fire resisting boards(eg . calcium silicate)<br /> c)proprietary fire resistant ductwork<br />eg: PROMATECT-H<br />Tuesday, June 07, 2011<br />31<br />Smoke Extraction In Buildings<br />
    32. 32. Protection of duct with fire resisting board<br />Tuesday, June 07, 2011<br />32<br />Smoke Extraction In Buildings<br />
    33. 33. Ductwork construction from fire resisting board<br />Tuesday, June 07, 2011<br />33<br />Smoke Extraction In Buildings<br />
    34. 34. Spreading of smoke<br />Tuesday, June 07, 2011<br />34<br />Smoke Extraction In Buildings<br />
    35. 35. Tuesday, June 07, 2011<br />35<br />Smoke Extraction In Buildings<br />
    36. 36. Tuesday, June 07, 2011<br />36<br />Smoke Extraction In Buildings<br />
    37. 37. Tuesday, June 07, 2011<br />37<br />Smoke Extraction In Buildings<br />
    38. 38. Design guide for different building types<br />Multi-storey office and similar buildings<br />Warehouse<br />Underground car parks/basement<br />Atrium buildings<br />Shopping malls<br />Tuesday, June 07, 2011<br />38<br />Smoke Extraction In Buildings<br />
    39. 39. Multi storey office and similar buildings<br />Phased evacuation<br />Evacuation time will be varying<br />Smoke should not spread<br /> 1, smoke extraction<br /> 2, pressurisation<br />The recirculation of air in normal hvac system is prevented by dampers<br />Tuesday, June 07, 2011<br />39<br />Smoke Extraction In Buildings<br />
    40. 40. Tuesday, June 07, 2011<br />40<br />Smoke Extraction In Buildings<br />
    41. 41. Important design considerations<br />The system is not for providing a smoke free layer<br />Both supply and extract ducts should be having fire resistance equal to that of the floors /walls<br />Exhaust fans should be able to run at the highest expected temperature<br />Tuesday, June 07, 2011<br />41<br />Smoke Extraction In Buildings<br />
    42. 42. The power supply to the system must be duplicated<br />The power and instrumentation cabling should be of fire resistant type<br />Smoke and fire dampers should be having suitable specification-UL555s<br /> class-I,II,III,IV<br /> in high storey buildings-wind pressure <br />Tuesday, June 07, 2011<br />42<br />Smoke Extraction In Buildings<br />
    43. 43. Ware houses<br />Tuesday, June 07, 2011<br />43<br />Smoke Extraction In Buildings<br />
    44. 44. Underground car parks/basement<br />Tuesday, June 07, 2011<br />44<br />Smoke Extraction In Buildings<br />
    45. 45. ATRIUM CONSTRUCTIONS<br />Fully enclosed atrium<br />Partially opened atrium<br />Fully opened atrium<br />Tuesday, June 07, 2011<br />45<br />Smoke Extraction In Buildings<br />
    46. 46. Tuesday, June 07, 2011<br />46<br />Smoke Extraction In Buildings<br />
    47. 47. Fully enclosed atrium<br />Tuesday, June 07, 2011<br />47<br />Smoke Extraction In Buildings<br />
    48. 48. Enclosures are 2 types<br /> 1- fire resisting enclosure-fire resisting glazing<br /> 2- enclosure of limited combustibility but not fire resisting<br />Tuesday, June 07, 2011<br />48<br />Smoke Extraction In Buildings<br />
    49. 49. Partially enclosed atrium<br />Tuesday, June 07, 2011<br />49<br />Smoke Extraction In Buildings<br />
    50. 50. Fully open atrium<br />Tuesday, June 07, 2011<br />50<br />Smoke Extraction In Buildings<br />
    51. 51. Shopping malls<br />Tuesday, June 07, 2011<br />51<br />Smoke Extraction In Buildings<br />
    52. 52. Extract from single shops<br />Smoke is prevented to enter to mall area<br />Very large fans are not required<br />But complex and costly<br />Shops must be sprinkled<br />Combined duct work is used to reduce cost<br />Tuesday, June 07, 2011<br />52<br />Smoke Extraction In Buildings<br />
    53. 53. Extract from mall<br />Tuesday, June 07, 2011<br />53<br />Smoke Extraction In Buildings<br />
    54. 54. Channeling screens<br />Tuesday, June 07, 2011<br />54<br />Smoke Extraction In Buildings<br />
    55. 55. Limitations<br />With high atriums there is a cut off point of mass flow rate of 150 to 250 kg/s-economically impractical.<br /> Temperature stratification<br />Cooling effect<br />Tuesday, June 07, 2011<br />55<br />Smoke Extraction In Buildings<br />
    56. 56. Fire,smoke and building code agencies<br />Industrial risk insurers (IRI)<br />Southern building code congress inc(SBCCI)<br />National fire protection association(NFPA)<br />Underwriters Laboratories(UL)<br />British standards(BS)<br />National Building Standards(NBS)<br />Tuesday, June 07, 2011<br />56<br />Smoke Extraction In Buildings<br />
    57. 57. CONCLUSION<br />By following discriminative approaches and methods needed for different types of buildings and constructions provided by the different approved agencies ,the threat from fire and smoke can be reduced to a considerable level.<br />Tuesday, June 07, 2011<br />Smoke Extraction In Buildings<br />57<br />
    58. 58. References<br />Promat International Ltd<br />National Fire protection Association,Guide for smoke and heat venting,NFPA-204 M<br />BS 5839: Fire Protection and alarm systems in buildings,Part1 2002<br />Underwriters Laboratories,Leakage rated dampers for use in smoke in control systems,UL555 S<br />Tuesday, June 07, 2011<br />58<br />Smoke Extraction In Buildings<br />
    59. 59. THANKING YOU ALL……..<br />Tuesday, June 07, 2011<br />59<br />Smoke Extraction In Buildings<br />

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