Fire safety in building

FIRE SAFETY IN BUILDINGSFIRE SAFETY IN BUILDINGS

Dr. A.K. GuptaDr. A.K. GuptaScientistScientist

Central Building Research InstituteCentral Building Research InstituteROORKEE- 247 667ROORKEE- 247 667

What is Fire ?

FIRE is a process of combustion characterized by the evolution of Heat, Light, and Smoke.

SMOKE is the cloud of finely dispersed solid matter like soot. Gray colour is due to the presence of water vapours.

What is Building ?What is Building ?

Any structure that includes foundation, plinth, Any structure that includes foundation, plinth, walls, floors, roofs, chimneys, plumbing and walls, floors, roofs, chimneys, plumbing and building services intended to enclose any land building services intended to enclose any land or space is called a Buildingor space is called a Building

Building is dynamic systemBuilding is dynamic system Contents change with timeContents change with time

What we provide today becomes obsolete What we provide today becomes obsolete tomorrow. tomorrow. Hence,Hence, Safety requirements need regular Safety requirements need regular attentionattention

Burning of Wood Burning of Wood

Match Stick

Thick log

TemperatureTemperature

Fuel

Vap

ori z

ati o

n ra

teFu

el V

apor

i zat

i on

r ate

Fire PointFire Point

Minimum required for Minimum required for sustained combustionsustained combustion

Fuel Vaporization rateFuel Vaporization rate

FIRE INITIATIONFIRE INITIATION

FuelFuel

FlameFlame

Products of CombustionProducts of Combustion

Radiation

Fuel Vapours

AIRAIR AIRAIR

Products of CombustionProducts of Combustion

SMOKE LIGHT (INFRA-RED) FLAME HEAT Pressure

COMPARTMENT FIRECOMPARTMENT FIRE

Compartment Fire – Door Closed

Compartment Fire – Door Open

1

Behaviour of Concrete in FireBehaviour of Concrete in Fire

• On Heating Concrete losses its strength

• No significant loss up to 2000C

• Significant loss occurs at 6000C

Very little residual strength is left after 6000C

Pressure Rise due to FirePressure Rise due to Fire

Fire Size = 100 kWFire Size = 100 kWRoom Volume = 28 mRoom Volume = 28 m33

Pressure Rise within 10 seconds = 7 kPaPressure Rise within 10 seconds = 7 kPaForce exerted on Walls = 5.8 kN/mForce exerted on Walls = 5.8 kN/m22

Sufficient to smash window glass.Sufficient to smash window glass.

Visibility Through SmokeVisibility Through Smoke

Visibility is defined as follows:Visibility is defined as follows:

Visibility = 10 / (db/m)Visibility = 10 / (db/m)(db/m) is the optical density (OD) of the smoke.(db/m) is the optical density (OD) of the smoke.

Max. Permissible value of OD = 2 db/mMax. Permissible value of OD = 2 db/mDesirable value of OD = 1 db/mDesirable value of OD = 1 db/m

Dense Smoke may have OD equal to 100 db/mDense Smoke may have OD equal to 100 db/m

Descendance of the Descendance of the Hot Gas Layer Hot Gas Layer

Clause 3.4.12.3, Page 24 of NBC states Clause 3.4.12.3, Page 24 of NBC states

Smoke Venting Facilities shall be adequate to Smoke Venting Facilities shall be adequate to prevent dangerous accumulation of smoke during prevent dangerous accumulation of smoke during the period of time necessary to evacuate the area the period of time necessary to evacuate the area served.served.

A minimum of 12 air changes per hour has been A minimum of 12 air changes per hour has been recommended.recommended.

FIRE SAFETY COMPRISES FIRE SAFETY COMPRISES OF: OF:

1.1. Life SafetyLife Safety2.2. Fire ProtectionFire Protection

FIRE SAFETYFIRE SAFETY

LIFE SAFETYLIFE SAFETY FIRE FIRE PROTECTIONPROTECTION

Design of

Egress Routs

Pressurization of

Protected Spaces

Active Measures

Passive Measures

1. Sprinkler

2. Detectors

3. Hydrants

4. Extinguishers

1. Compartmentation

2. Fire Retardant

3. Fire Resistance

FIRE SAFETY ENGINEERING

LIFE SAFETY

DESIGN OF EGRESS ROUTES

PRESSURISATION OF PROTECTED

SPACES

FIRE SAFETY

FIRE PREVENTION

FIRE PROTECTION

PASSIVEGOOD HOUSE KEEPING

MATERIALS ACTIVE

FIRERESISTANTSTRUCTURE

MINIMISE ACCUMULATION OF COMBUSTIBLES

COMPART-MENTATION

FIRE RETARDANTMATERIALS

FIREVENTING

FIRE EXTINGUISH-MENT

FIRE DETECTOR

MANUAL AUTOMATIC MANUAL AUTOMATIC

EXTIN-GUISHERS

HYDRANTSYSTEM

AUTOMATICSPRINKLER SYSTEM

FLOODING SYSTEMS

STOICHIOMETRIC BURNING OF METHANESTOICHIOMETRIC BURNING OF METHANE

CH4 + 2O2 CO2+2H2O

16 64 44 36

Since the reaction is not complete, traces of CO, HCL, HCN Since the reaction is not complete, traces of CO, HCL, HCN etc are also found in the products of combustion etc are also found in the products of combustion

Reactants Products of combustion

Fuel 1 Kg CO2 : 2.75 Kg

Air 16 Kg ((Approx) ) H2O : 2.25 Kg

N2 :12.0 Kg (Approx)

LIFE SAFETY -1LIFE SAFETY -1

SMOKE:SMOKE:

IRRITANTS:IRRITANTS:

ASPHYXIANTS/ NARCOTICS:ASPHYXIANTS/ NARCOTICS:

Smoke is defined as the airborne solid and liquid Smoke is defined as the airborne solid and liquid particulates. Toxicant gases are divided into two: particulates. Toxicant gases are divided into two:

Capable of causing depression in the central nervous Capable of causing depression in the central nervous system with loss of consciousness and ultimate death. system with loss of consciousness and ultimate death. CO and HCN are acute toxicants.CO and HCN are acute toxicants.

Causes irritation to sensory and pulmonary system. Causes irritation to sensory and pulmonary system. Sensory irritation includes eyes and respiration tract and Sensory irritation includes eyes and respiration tract and pulmonary includes lungs.pulmonary includes lungs.


Carbon Monoxide: Carbon Monoxide:

Toxicity of CO is due to its affinity for hemoglobin to form COHb resulting in decreased supply of oxygen to body tissues. The critical limits of exposure is determined as follows:

Concentration x time = 35,000 ppm-min.

10 minutes exposure to 3,500 ppm is hazardous

Safe upto 100 ppm exposure


HYDROGEN CYANIDE:HYDROGEN CYANIDE:

Hydrogen cyanide is 20 times more toxic than carbon monoxide. It does not react with hemoglobin but inhibits the use of oxygen by cells. The concentration-time rule is

Concentration x time = 1500 ppm-min

50 ppm may be tolerated upto 30 min


HYDROGEN CHLORIDE:HYDROGEN CHLORIDE:• HCL is a sensory as well as pulmonary irritant

• 75 ppm is extremely irritating to eyes and upper respiratory tract

17% impairs motor co-ordination 11% causes headache 9% Shortness of breathe, nausea 3.2% death within 45s

OXYGEN:OXYGEN:


HEAT EFFECT:HEAT EFFECT:

Threshold to human tenability to heat fluxes: 1.2 - 2.5 kW/m2

SkinSkin Time (s)Time (s)

Temperature (C)Temperature (C)

7171 6060 Second degree burnsSecond degree burns

8282 3030 Second degree burnsSecond degree burns

100100 15 15 Second degree burns pulse rate Second degree burns pulse rate jumps to 120 beats/minjumps to 120 beats/min

148148 -- Second degree burns pulse rate Second degree burns pulse rate soars to 176 beats/minsoars to 176 beats/min

160160 -- Extreme painExtreme pain

Building EvacuationBuilding Evacuation

BASIS:ASET : Available Safe Egress Time

To be determined through available model

RSET : Required Safe Egress Time

RSET .LE. ASET

T-HELP : Time for Human Escape and Life Potential

RSET .NG. T-HELP

T-HELP: Time for Human Escape and Life PotentialT-HELP: Time for Human Escape and Life Potential

T-HELP = tinc- tdet

“Inc“ refers to the time of incapacitation, and

“det” Refers to the time of detection

T-HELP CRITERIAT-HELP CRITERIA

CRITERION-1CRITERION-1

-- whichever comes firstwhichever comes first

-- whichever comes firstwhichever comes first

Upper layer reaches to head level or its temperature reaches to 100 deg C.

Upper layer reaches to floor level or its temperature reaches to 160 deg C.

CRITERION-2CRITERION-2

Fire Fire ProtectionProtection

ROOM TEMPERATUREROOM TEMPERATURE

Onset of Hazardous condition Onset of flash Over Structure Collapse

Determination of Room Temperature is important for:Determination of Room Temperature is important for:

CLASSIFICATION OF FIRECLASSIFICATION OF FIRE

CLASS CLASS AA FIRES: FIRES:

CLASS CLASS CC FIRES: FIRES:

CLASSCLASS B B FIRES: FIRES:Fire involving cellulosic material such as cotton, wood & Fire involving cellulosic material such as cotton, wood & paperpaper

Fire involving flammable liquidFire involving flammable liquid

Fire involving electrical equipmentFire involving electrical equipmentCLASS CLASS DD FIRES: FIRES:Fire involving metals – Na, K, Li and ZrFire involving metals – Na, K, Li and Zr

Light Hazard –Light Hazard –Occupancies Include::Occupancies Include::

Light Hazard – Occupancies or Portions of other Light Hazard – Occupancies or Portions of other Occupancies where quantity and/ or combustibility Occupancies where quantity and/ or combustibility is low and fire with relatively low rates of heat is low and fire with relatively low rates of heat release are expected,release are expected,

ChurchesChurches MuseumsMuseumsClubsClubs Nursing or Convalescent HomeNursing or Convalescent HomeEducational Educational Office, Including Data ProcessingOffice, Including Data ProcessingHospitals Hospitals ResidentialResidentialInstitutionalInstitutional Restaurant seating areasRestaurant seating areasLibraries, except largeLibraries, except large Theaters and Theaters and Auditoriums Auditoriums Stack rooms Stack rooms excluding stage and excluding stage and prosceniumsprosceniums

Light hazard OccupanciesLight hazard Occupancies

Ordinary Hazard Occupancies (Group 1) Ordinary Hazard Occupancies (Group 1) Include:Include:

Ordinary Hazard (Group 1) – Occupancies or Portions of Ordinary Hazard (Group 1) – Occupancies or Portions of other Occupancies where combustibility is low, quantity of other Occupancies where combustibility is low, quantity of combustibles is moderate, stock piles of combustibles do combustibles is moderate, stock piles of combustibles do not exceed 8 ft, and fire with moderate rate of heat release not exceed 8 ft, and fire with moderate rate of heat release are expected,are expected,

Automobile ParkingAutomobile Parking Electronic plantsElectronic plantsGaragesGarages Glass and Glass Glass and Glass ProductsProductsBakeriesBakeries ManufacturingManufacturingBeverage Manufacturing Beverage Manufacturing LaundriesLaundriesCanneriesCanneriesDairy Products Mfg. & ProcessingDairy Products Mfg. & Processing

Ordinary Hazard Occupancies (Group Ordinary Hazard Occupancies (Group 1)1)

Ordinary Hazard Ordinary Hazard Occupancies (Occupancies (Group 2) Group 2) Include:Include:

Ordinary Hazard (Group 2) – Occupancies or Ordinary Hazard (Group 2) – Occupancies or Portions of other Occupancies where quantity and Portions of other Occupancies where quantity and combustibility of contents is moderate, stock combustibility of contents is moderate, stock piles do not exceed 12 ft, and fire with moderate piles do not exceed 12 ft, and fire with moderate rate of heat release are expected rate of heat release are expected

Cereal MillsCereal Mills MercantileMercantileChemical Plant- Ordinary Chemical Plant- Ordinary Machine Shops Machine Shops Cold Storage Wherehouses Cold Storage Wherehouses Metal Working Metal Working Confectionary ProductsConfectionary Products Printing and PublishingPrinting and PublishingDistilleriesDistilleries Textile Mfg.Textile Mfg.Leather Goods Mfg.Leather Goods Mfg. Tobacco Products Tobacco Products Mfg.Mfg.Libraries-Large Stack-Libraries-Large Stack- Wood Product AssemblyWood Product AssemblyRoom AreaRoom Area

OrdinaryOrdinary Hazard Occupancies (Group Hazard Occupancies (Group 2)2)

Ordinary Hazard (Group 3) –Ordinary Hazard (Group 3) –Occupancies Include::Occupancies Include::

Ordinary Hazard (Group 3) – Occupancies or Portions Ordinary Hazard (Group 3) – Occupancies or Portions of other Occupancies where quantity and/ or of other Occupancies where quantity and/ or combustibility of contents is high, and fires of high combustibility of contents is high, and fires of high rate of heat release are expected,rate of heat release are expected,

Exhibition HallsExhibition Halls Repair Garages Repair GaragesFeed MillsFeed Mills Tire Manufacturing Tire Manufacturing Paper and Pulp Mills Paper and Pulp Mills Warehouses ( having Warehouses ( having moderatemoderatePaper and Process Plants combustibility of content suchPaper and Process Plants combustibility of content such

as paper, household furniture, as paper, household furniture, paint, general storage, whiskey, paint, general storage, whiskey,

etc.)etc.) Wood MachiningWood Machining

Ordinary Hazard Occupancies (Group Ordinary Hazard Occupancies (Group 3)3)

Extra Hazard Occupancies Include::Extra Hazard Occupancies Include::

Extra Hazard-Occupancies or Portions of other Extra Hazard-Occupancies or Portions of other occupancies where quantity and combustibility of occupancies where quantity and combustibility of contents is very high, flammable liquids, dust, Lint, or contents is very high, flammable liquids, dust, Lint, or other materials are present introducing the probability of other materials are present introducing the probability of rapidly developing fires with high rates of heat release.rapidly developing fires with high rates of heat release.

Aircraft HangarsAircraft Hangars Explosive and Pyrotechnics Explosive and PyrotechnicsChemical WorksChemical Works Woodworking with Woodworking with flammableflammable(Extra Hazard)(Extra Hazard) Finishing FinishingCotton Pickers andCotton Pickers andOpening OperationsOpening Operations

Extra Hazard OccupanciesExtra Hazard Occupancies

Flash PointFlash Point

Lowest temperature at which liquid Lowest temperature at which liquid produces enough vapour to form a produces enough vapour to form a flammable mixtureflammable mixture

Highly FlammableHighly Flammable : 00 – 32 : 00 – 3200CCFlammableFlammable : 32 – 60 : 32 – 6000CC

CombustibleCombustible : Above 60 : Above 6000C C

FIRE SAFETY STRATEGYFIRE SAFETY STRATEGY

Safe building, equipment and processesSafe building, equipment and processes Elimination of causes of fireElimination of causes of fire Training and education for good housekeeping Training and education for good housekeeping

and and emergency actionemergency action Provision of protection / fighting equipmentProvision of protection / fighting equipment Maintenance of protective equipment in Maintenance of protective equipment in

readinessreadiness

Over 125 equipmentOver 125 equipment

InbuiltInbuilt

PortablePortable Manual Manual (Fixed)(Fixed)

Fixed Fixed (Automatic)(Automatic)

Used by Used by FiremenFiremen

ExtinguishersExtinguishers Hydrant Hydrant SystemSystem

SprinklersSprinklers

DetectorsDetectors

Flooding Flooding SystemSystem

Fire TenderFire Tender

SnorkelSnorkel

Protective Protective EquipmentEquipment

Automatic Sprinkler SystemAutomatic Sprinkler System`

Water Application Rate of Sprinklers

Hazard Minimum Discharge Area of DurationHazard Minimum Discharge Area of DurationClass Pressure Density Operation (min)Class Pressure Density Operation (min) (bars) (mm/min) (m(bars) (mm/min) (m22))

ELH 2.20 2.25 84 30ELH 2.20 2.25 84 30OH1 1.00 5.00 72 60OH1 1.00 5.00 72 60OH2 1.40 5.00 144 60OH2 1.40 5.00 144 60OH3 1.70-2.00 5.00 216-360 60OH3 1.70-2.00 5.00 216-360 60EHH - 7.50-12.50 260 90EHH - 7.50-12.50 260 90(Process) (Process) EHH - 7.50-17.50 260 90EHH - 7.50-17.50 260 90(Storage)(Storage)

Water Discharge Rate of Sprinklers

Q = K (P) 1/2Q = K (P) 1/2Where,Where,

Q = Water Discharge Rate (lpm)Q = Water Discharge Rate (lpm)P = Water Pressure, barsP = Water Pressure, barsK = Orifice coefficientK = Orifice coefficient

= 57 for 10 mm Sprinklers= 57 for 10 mm Sprinklers = 80 for 15 mm Sprinklers= 80 for 15 mm Sprinklers = 115 for 20 mm Sprinklers= 115 for 20 mm Sprinklers


Pressure Sprinkler SizePressure Sprinkler Size (bars) 10 mm 15 mm 20 mm(bars) 10 mm 15 mm 20 mm

0.690 47 66 950.690 47 66 95 1.035 58 81 1161.035 58 81 116 1.380 67 93 1351.380 67 93 135 1.725 75 105 1501.725 75 105 150 2.415 88 124 1782.415 88 124 178 3.450 105 148 2123.450 105 148 212 5.175 129 182 2615.175 129 182 261 6.900 149 210 3026.900 149 210 302

Maximum Coverage per Sprinkler

Hazard Coverage Spacing Between SprinklersHazard Coverage Spacing Between Sprinklers

Class (mClass (m22) (m)) (m)

ELH 21 4.5 ELH 21 4.5

OH1 OH1 OH2 12 3.5OH2 12 3.5OH3OH3

EHH EHH (Process) 09 3.0 (Process) 09 3.0 (Storage)(Storage)

Common PerceptionCommon Perception

What is IgnoredWhat is Ignored

What is commonly prescribedWhat is commonly prescribed

00 NoneNone0000 Extinguishers Extinguishers 000000 Dry/Wet HydrantsDry/Wet Hydrants00000000 Sprinklers/ DetectorsSprinklers/ Detectors

Safe & adequate size and Numbers of Escape Safe & adequate size and Numbers of Escape RoutesRoutes

TWO APPROACHES TO FIRE SAFETY TWO APPROACHES TO FIRE SAFETY Strategy Strategy

1.1. Prescription based fire safetyPrescription based fire safety2.2. Performance based fire safetyPerformance based fire safety

PERFORMANCE BASED FIRE SAFETY PERFORMANCE BASED FIRE SAFETY DESIGNDESIGN

STARTSTART

STOPSTOP

FIRE SAFETY PLAN OF A FIRE SAFETY PLAN OF A BUILDINGBUILDING

FIRE MODELFIRE MODEL

Prediction of impacts under design fire conditionsPrediction of impacts under design fire conditions

SAISFY SAISFY CRITERIA ?CRITERIA ?

YESYES

NONO

Design Fire ConditionsDesign Fire Conditions

Standard Safety CriteriaStandard Safety Criteria

What is a Model?What is a Model?

Physically of mentally contrived emulation of ‘reality’ suggested by what understanding we have of the phenomenon

MODEL POTENTIAL

A Model must have capacity or ‘potential to be valuable

A model is valuable depends upon the case and how the model is employed

A model which has the potential to be valuable may not be valuable in a given case because it may be inappropriate for that case.

FIRE MODELLINGFIRE MODELLING

M O D E LM O D E LUnderstanding of fir

e dynamics

Numerical Mathematics Ana

lysi

s of

Res

ults

and

Val

idat

ion

200

400

600

800

200 400 600 800 1000

1200Time(S)

Tem

pera

ture

(C)

Fire Model: Limitations-1Fire Model: Limitations-1

Validation: means proven correct, but term validation is misleading in itself, because validation is carried out with a limited set of experiments only.

Shows that there is a need for repetition of experimental tests.

FOR EXAMPLE:FOR EXAMPLE:

Fire Model: Limitations-2Fire Model: Limitations-2

Ranking of Predicted Temperature TESTTEST

Foam Slab HouseHouse Deptt. StoreDeptt. Store

Highest FIRST FAST ASET

Middle - ASET FAST

Lowest FAST FIRST FIRST

Comparison with experiments under identical inputsComparison with experiments under identical inputs

Conclusion: We can not assume consistency of prediction of one model in relation to another model

DEVELOPED MODELSDEVELOPED MODELS

CALFIRE CALculate Fire in Room and Enclosures

FIREMAP Fire Induced Risk Evaluation and Mapping

SAFE-R Safe and Accessible Fire Escape - Routes

SEEM Stack Emission Engineering Model

BUILDING EVACUATION-1BUILDING EVACUATION-1

Emergent Evacuation - Why ? Fire Earthquake Toxic Gas Release Bomb Threat Civil Defence Preparedness, etc

Simple exuberance of a member of the crowdSimple exuberance of a member of the crowd may cause stampede may cause stampede resulting in crushing and trampling.resulting in crushing and trampling.

Inadequate number and size of escape routes cause backtracking and Inadequate number and size of escape routes cause backtracking and creates bottlenecks.creates bottlenecks.

Building EvacuationBuilding EvacuationWhat is Needed ?What is Needed ?

• Adequate Number of Escape RoutesAdequate Number of Escape Routes• Adequate Width of the Escape RouteAdequate Width of the Escape Route•Reduced Complexity of the MovementReduced Complexity of the Movement•Escape Routes are Properly ProtectedEscape Routes are Properly Protected

Inadequate size and number of escape routes Inadequate size and number of escape routes create bottlenecks that may cause stampede, create bottlenecks that may cause stampede, crashing, and trampling.crashing, and trampling.

I. Identification of paths for each source node,

II. Calculation of traversal time of each path,

III. Determination of dynamic capacity of each path,

IV. Arranging paths in ascending order in terms of traversal time,

V. Calculation of number of evacuees per unit time step,

VI. Presentation of result in tabular form,

SAFE-R methodologySAFE-R methodology


SAFE-R MODEL

Has been developed to plan the evacuation process Identification of Paths for each Source Node Calculate Traversal Time of each Path Calculate Dynamic Capacity of each Path Number of evacuees per unit time Helps to reject the use of longer Paths Helps to reduce bottlenecking and waiting time


SAFE – R Input

Dynamic Capacity of the Arc

- Doorways : 1.0 P/m/s

- Level Passage : 1.2 P/m/s

- Stairways : 0.8 P/m/s Walking Speed : 0.5 – 1.0 m/s Initial Content : 12.5 m2/P Node Capacity : 0.5 m2/P


SAFE-R NETWORKBuilding plan is represented in the form of a network of Nodes and Arcs.

Node represents spaces such as Hall, Room, Corridor

Arc represents the connection between two Nodes

Example:Room Node Exit

Nodes : Source node (Room)

Exit node (Open)

Arc : Door between Room & Open

Building LayoutBuilding Layout

70

70

72

ROOM 301

ROOM 302 ROOM 303

ROOM 201

ROOM 202

ROOM 101

GROUND LEVEL

2nd LEVEL

3 LEVEL

ROOM 301

ROOM 302 ROOM 303

ROOM 201

ROOM 202

ROOM 101

GROUND LEVEL

3rd LEVEL

WP1.3

HA1.3LA1.3 LA2.3

WP2.3 WP3.3

SW2.3

WP1.2

LA1.2 HA1.2 LA2.2

WP2.2

SW2.2

SW1.2

HA2.1

LO1.1

HA1.1

WP1.1

SW1.2 Contd. SW2.2 Contd.HA

3.1

DS2.1

DS1.1

SW1.3

ROOM 301

ROOM 302 ROOM 303

ROOM 201

ROOM 202

ROOM 101

GROUND LEVEL

2nd LEVEL

3 LEVEL

ROOM 301

ROOM 302 ROOM 303

ROOM 201

ROOM 202

ROOM 101

GROUND LEVEL

3rd LEVEL

WP1.3

HA1.3LA1.3 LA2.3

WP2.3 WP3.3

SW2.3

WP1.2

LA1.2 HA1.2 LA2.2

WP2.2

SW2.2

SW1.2

HA2.1

LO1.1

HA1.1

WP1.1

SW1.2 Contd. SW2.2 Contd.HA

3.1

DS2.1

DS1.1

SW1.3

SAFE-R Network of the example building

a,b,c

Node Number

No. of Occupants

a is the arc numberb is the dynamic capacityc is the traversal time period

a,b,c

Node Number

No. of Occupants


a,b,c

Node Number

No. of Occupants


0

70 0

070

6

19

72

18

16 174 5

20

13 15

11 122 3

14

1

10

7 9

8

21

Exit Node

21

Exit Node

1,3,3

2,6,4

6,8,1

10,5,5,

13,5,4

19,5,4

21,5,4

25,3,3 26,3,3

18,3,317,3,3

22,16,1 23,0,0

27,0,0

24,3,4

20,3,4

16,3,4

11,2,9

14,14,1 15,0,0

9,6,48,6,4

5,3,34,6,3

7,14,4

3,3,1

Source Node

Source Node Dummy Node

Dummy Node

Dummy Node

Source Node

00

7070 00

007070

6

19

72

18

16 174 5

20

13 15

11 122 3

14

1

10

7 9

8

21

Exit Node

21

Exit Node

1,3,3

2,6,4

6,8,1

10,5,5,

13,5,4

19,5,4

21,5,4

25,3,3 26,3,3

18,3,317,3,3

22,16,1 23,0,0

27,0,0

24,3,4

20,3,4

16,3,4

11,2,9

14,14,1 15,0,0

9,6,48,6,4

5,3,34,6,3

7,14,4

3,3,1

Source Node

Source Node Dummy Node

Dummy Node

Dummy Node

Source Node

Paths identified by SAFE-R model

Path for Source Node: 1 Path-1 : 1 7 8 21 Path-2 : 1 7 10 9 21 Path-3 : 1 7 21 Path-4 : 1 9 21 Path-5 : 1 10 7 8 21 Path-6 : 1 10 7 21 Path-7 : 1 10 9 21 Path for Source Node: 2 Path-9 : 2 14 13 11 7 8 21 Path-9 : 2 14 13 11 7 10 9 21 Path-10 : 2 14 13 11 7 21 Path-11 : 2 14 15 12 9 21 Path-12 : 2 14 15 12 10 7 8 21 Path-13 : 2 14 15 12 10 7 21 Path-14 : 2 14 15 12 10 9 21 Path for Source Node: 4 Path-15 : 4 19 18 16 13 11 7 8 21 Path-16 : 4 19 18 16 13 11 7 10 9 21 Path-17 : 4 19 18 16 13 11 7 21 Path-18 : 4 19 20 17 15 12 9 21 Path-19 : 4 19 20 17 15 12 10 7 8 21 Path-20 : 4 19 20 17 15 12 10 7 21 Path-21 : 4 19 20 17 15 12 10 9 21

Path Number

Source Node

Traversal Time

Dynamic Capacity

Initial Capacity

1 1 10 3 722 1 12 3 723 1 4 6 724 1 4 3 725 1 15 3 726 1 9 6 727 1 9 3 728 2 20 3 709 2 22 3 70

10 2 14 3 7011 2 14 2 7012 2 28 2 7013 2 22 2 7014 2 22 2 7015 4 28 3 7016 4 30 3 7017 4 22 3 7018 4 22 2 7019 4 36 2 7020 4 30 2 7021 4 30 2 70

Source Node

Initial Content

Path Utilized % of people flowing

1

72

Path – 3 1 7 21 65%

Path – 4 1 9 21 29%

Path – 6 1 10 7 21 06%

2

70

Path –10 2 14 13 11 7 21 51%

Path –11 2 14 15 12 9 21 33%

Path – 8 2 14 13 11 7 8 21 07%

Path –13 2 14 15 12 10 7 21 09%

3

70

Path –15 4 19 18 16 13 11 7 8 21 50%

Path –17 4 19 18 16 13 11 7 21 29%

Path –18 4 19 20 17 15 12 9 21 10%

Path –20 4 19 20 17 15 12 10 7 21 11%

Most utilized paths for each source node

Number of people left inside the building at any instant of timeNumber of people left inside the building at any instant of time

0

50

100

150

200

250

0 25 50 75 100 125 150 175 200

Time,s

No. o

f peo

ple

insi

de th

e bu

ildin

g SAFE-R EVACNET+

September 11,

2001

Safety Features

Wind load of 320 kmpH hurricane

Worst Seismic load in Aleutian Tectonic Plate

Sprinkler System

Fire alarm system

Escape routes

Two Hours fire resistance

Fuel Load : 90,000 lit.

Fuel Density : 0.8 kg/lit.

Fuel Mass : 72,000 kg

Heat of Comb : 44 MJ/kg

Fire Load : 3.168 x 106 MJ

Fire Duration : 1 hr

Heat release rate : 880 MW

Equivalent to 2 NAPS or 2 Super TPPs.

Fire Load

Floor Area : 4,032 m2

Building Volume : 1.66 x 106 m3

Air Density : 1.0 kg/m3

Air Mass : 1.66 x 106 kgSpecific Heat : 1.2 kJ/kg-K

T = 3168 x 106/1.66 x 106 x 1.2T = 15900 C

Assumption : Building is insulated

Room Temperature – 1

Room Temperature – 2Plane Strike : 300 m from baseHeight involved : 112 mAir mass : 4032 x 112

: 0.45 x 106 kg

Energy lost to ambient : 60 – 80%

T = 23460 C with 60% losses. = 17600 C with 70% losses.

Reported temperature : 17270 C

Melting Point of Steel : 15700 C

Fire Resistance - 1

Steel Columns covered with insulating material provided guarantee to stand for a minimum of 2 hrs during normal fire conditions, i.e.,

Fire Resistance = 2 hrs.

Fire Resistance is determined in a Standard Furnace, whose temperature is raised in accordance with

T = 345 log 10 (8t + 1)

t is time in min.

Theoretical Fire Resistance – 1

25mm Insulation Board.. 25mm thick, hollow steel column

SteelInsulation

i

Tf

di

Ts

isss

sfiis

dCVTTA

dtdT

?TC 1727T

s

Of

Heat balance provides

0

200

400

600

800

1000

1200

1400

1600

1800

2000

Time, S

Tem

pera

ture

, CColumn temperature under real time fire

Standard time – temperature curve

30 min 50 min

1570

Theoretical Fire Resistance – 2

Column temperature under standard fire

0

200

400

600

800

1000

1200

Time, S

Tem

pera

ture

, C

Fire Severity is defined as area under the curve. Fire Severity should remain Constant. Fire Severity in the present area is equal to 97429.250 C-min

Equivalence of Fire Severity - 1

Standard time – temperature curve

1727 x t = 97429.25

t = 57 min

Very close to the time of Collapse

Equivalence of Fire Severity - 2Under the influence of elevated temperature,

fire resistance reduces.

Tem

pera

ture

, oC

Time, min

1727

?

CALFIRE Example

ProblemProblem

Domestic pan fireDomestic pan fire

Will Kitchen fan cope with volume of Will Kitchen fan cope with volume of Smoke:Smoke:

VENT/ FAN SIZE

Information on the proper size of VENT or for deciding suitable specification of an extractor FAN is required to check the descent of the hot gas layer below a certain level.

CALFIRE Example

Visualize ProblemVisualize Problem

FloorFloor == 3m x 4m3m x 4mHeightHeight == 2.4m2.4mClear HeightClear Height == 2.0m2.0mFire HeightFire Height == 1.0m1.0m

CALFIRE Example

Heat Release RateHeat Release RatePool Fire , dia 0.2mPool Fire , dia 0.2m

Fuel Liquid Hydrocarbon Fuel Liquid Hydrocarbon

HRR = 13kWHRR = 13kW

CALFIRE Example

Layer TemperatureLayer Temperature

Room SizeRoom Size 3x4x2.43x4x2.4

Door OpenDoor Open 1.0x2.01.0x2.0

TemperatureTemperature 55.5 55.5 00CC

CALFIRE Example

Normal VentilationNormal Ventilation3 room volumes/ hour3 room volumes/ hour

Volume rateVolume rate 0.024 M0.024 M33/s/s

Mass rateMass rate 0.028 kg/s0.028 kg/s(normal temp)(normal temp)

Mass rate hot smokeMass rate hot smoke 0.025 kg/s0.025 kg/s

CALFIRE Example

Plume CalculationsPlume Calculations

Room HeightRoom Height 2.40 m2.40 mFire HeightFire Height 1.00 m1.00 mLayer depthLayer depth 0.40 m0.40 mMass FlowMass Flow 0.15 kg/s0.15 kg/s

CALFIRE Example

ConclusionConclusion

Need to increase extraction rate by Need to increase extraction rate by factor of 6 to maintain layer 2.0m factor of 6 to maintain layer 2.0m above floor.above floor.

Thank You

Conclusions Initially, the individual floor perimeter columns collapsed due to

combination of factors such as high temperature and aircraft debris. The fire continued for about an hour, steel columns melted, fire

resistance reduced to one fourth. Large amount of heat transferred to lower portion through radiation

and conduction, thus weakening the structure below. The columns started buckling after loosing strength and over

loading. Once the floor collapsed, each new falling floor added to the

downward force. Subsequently, the upper portion fell and hit the intact structure below.

High speed express elevators helped in removing people @ 1.375 persons per second per elevator, i.e. 4,950 persons per hour per elevator.

Had the impact zone been lower, the structure may have fallen like a tree.

Automatic Sprinkler SystemAutomatic Sprinkler System`

Water Application Rate of Sprinklers

Hazard Minimum Discharge Area of DurationHazard Minimum Discharge Area of DurationClass Pressure Density Operation (min)Class Pressure Density Operation (min) (bars) (mm/min) (m(bars) (mm/min) (m22))

ELH 2.20 2.25 84 30ELH 2.20 2.25 84 30OH1 1.00 5.00 72 60OH1 1.00 5.00 72 60OH2 1.40 5.00 144 60OH2 1.40 5.00 144 60OH3 1.70-2.00 5.00 216-360 60OH3 1.70-2.00 5.00 216-360 60EHH - 7.50-12.50 260 90EHH - 7.50-12.50 260 90(Process) (Process) EHH - 7.50-17.50 260 90EHH - 7.50-17.50 260 90(Storage)(Storage)


Pressure Sprinkler SizePressure Sprinkler Size (bars) 10 mm 15 mm 20 mm(bars) 10 mm 15 mm 20 mm

0.690 47 66 950.690 47 66 95 1.035 58 81 1161.035 58 81 116 1.380 67 93 1351.380 67 93 135 1.725 75 105 1501.725 75 105 150 2.415 88 124 1782.415 88 124 178 3.450 105 148 2123.450 105 148 212 5.175 129 182 2615.175 129 182 261 6.900 149 210 3026.900 149 210 302


Q = K (P) 1/2Q = K (P) 1/2Where,Where,

Q = Water Discharge Rate (lpm)Q = Water Discharge Rate (lpm)P = Water Pressure, barsP = Water Pressure, barsK = Orifice coefficientK = Orifice coefficient

= 57 for 10 mm Sprinklers= 57 for 10 mm Sprinklers = 80 for 15 mm Sprinklers= 80 for 15 mm Sprinklers = 115 for 20 mm Sprinklers= 115 for 20 mm Sprinklers

Maximum Coverage per Sprinkler

Hazard Coverage Spacing Between SprinklersHazard Coverage Spacing Between Sprinklers

Class (mClass (m22) (m)) (m)

ELH 21 4.5 ELH 21 4.5

OH1 OH1 OH2 12 3.5OH2 12 3.5OH3OH3

EHH EHH (Process) 09 3.0 (Process) 09 3.0 (Storage)(Storage)