Anatomy of a Fire. Christopher Crivello, MSFPE, PE. Douglas Nadeau, MSFPE, PE, CFPS, LEED AP

Transcription

1 Anatomy of a Fire Douglas Nadeau, MSFPE, PE, CFPS, LEED AP President of RAN Fire Protection Engineering, PC Vice President of truvue Inspection Technology Christopher Crivello, MSFPE, PE Fire Protection Project Engineer at RAN Fire Protection Engineering, PC ccrivello@ranfpe.com dnadeau@ranfpe.com

2 Agenda Introduction Short History of Fire Protection Fire Dynamics Fire Protection Systems Egress Case Study - Blessings Tavern Fire

3 Today s Goal Provide the basics of fire dynamics Give reason to Fire protection means more than the Code Look at buildings different tomorrow Learn how fire protection can save your life

4 Goals of Fire Protection The goal of fire protection is: Protection of Life Protection of Property Continuity of Business Operations

5 Rules of Thumb Rules of Thumb a procedure or rule based on experience of practice An example is: Loss of 5 psi in water pressure per story of a building If it leaves ash behind it may be a Class A fire

6 Rules of Thumb Rules of Thumb can and do lead to: Myths Misapplications Bad Decisions

7 Fire Protection Designs Rules of Thumb

8 The typical FPE answer It depends

9 Depends Fire Protection Designs depends on: The building The fire The occupants The fire department The fire protection systems Etc..

10 Depends Rules of Thumb cannot substitute for: Knowledge of the code Scientific facts Good design decisions Knowing the reason for an action We want to avoid we always did it this way.

11 Depends leads to Communication Building Owner Architect t Engineer Code Enforcement Officials The Public

12 How Fire Protection is Perceived There are 3 main classifications of thought in relation to fire protection Code Based Statistics Based Performance Based

13 Agenda Introduction Short History of Fire Protection Fire Dynamics Fire Protection Systems Egress Case Study - Blessings Tavern Fire

14 Fire Protection Engineering History To understand the practice of fire protection engineering it is essential to understand its history. A condensed d version is presented here

15 Derivation of FPE Codes, regulations, and fire departments began after major fires: 1835 New York 1861 London 1871 Chicago 1872 Boston 1906 San Francisco Rules initially from experience of fire fighters, builders, architects, & engineers Little understanding of fire dynamics, structural behavior, and human behavior

16 Brief History of Fire Protection Fire protection is one of the youngest engineering trades Great London Fire of first building regulations 1 st professional fire brigade 1824 (London) Patent for an automatic sprinkler was awarded to Henry S. Parmelee in 1874

17 Fire Protection Building separation distances conflagrations Compartmentation Egress travel distances Active systems sprinkler systems Passive systems fire resistance ratings

18 Brief History of Fire Protection 1896 NFPA formed Discipline i of fire engineering i emerged in the early 20th century as a distinct discipline, i in response to new fire problems posed by the Industrial Revolution

19 Fires of the 1960s Issues with smoke management Issues with material selection Structural t problems Limited FPE knowledge but more complex buildings False sense of security with codes Codes slow progress of innovation

20 Today s Codes & Standards Construction is advancing much faster than the codes Construction methods, Size and complexity, Technology, ect Innovation advancing faster than educating engineers ability to use codes & standards Performance Based Designs

21 Agenda Introduction Short History of Fire Protection Fire Dynamics Fire Protection Systems Egress Case Study - Blessings Tavern Fire

22 Combustion Process FIRE TRIANGLE FIRE TETRAHEDRON Retrieved November 30, Fires can be prevented or suppressed by removing any one of these.

23 Chemical Reaction A little more on the chemical reaction: To have combustion a chemical reaction between heat, fuel and oxygen Foundation of how fires begin Link

24 Suppressing the Fire Tetrahedron Fuel remove or shut off a supply Oxygen lower the amount within a compartment Heat cool by applying a suppression agent Chemical Reaction use chemical suppressants or salts

25 What is a fire? Uncontrolled exothermic reaction C b ti h i l ti Combustion a chemical reaction involving fuel, heat, and an oxidizer

26 Types of Flames Diffusion flames Premixed flames Link

27 Diffusion Flames Fick s Law combustion where fuel gas and oxygen are transported to a reaction zone Natural flaming fires are diffusion flames Link

28 Premixed Flames Mixing of fuel gas and oxygen prior to ignition Controlled example - Bunsen burner Uncontrolled example confined space methane leak Link

29 Fire Growth A fire grows in a self-sustaining sustaining manner Heat released from a fire is transferred to other nearby fuel packages Fire growth can be predicted within reason

30 Heat Transfer Combustion gives off heat which can ignite nearby fuels Heat energy always flows from hotter to colder 3 methods of heat transfer Conduction Convection Radiation

31 Conduction Heat transfer from direct contact

32 Convection Heat transfer through a fluid such as air or Heat transfer through a fluid such as air or liquid

33 Radiation Transfer of heat in the form of an invisible energy wave Becomes highly significant at higher temperaturest

34 Stages of Fire Growth Ignition Established Burning Growth Flashover Full Room Involvement (FRI) Post FRI

35 Stages of Fire Growth Ignition incipient phase, does not heat up the room Growth (Established Burning) Waste basket type fire that is self sustaining Demarcation between prevention and building fire design Fully Developed enough fuel and oxygen available Decay occurs when all fuel is consumed

36 Fire Growth Curves Q= t 2

37 Fire Growth Curve C 1000 Beginbrand Groeifase Volontwikkeld Doven FULL ROOM INVOLVEMENT 800 ESTABLISHED BURNING FIRE GROWTH Flashover POST FULL ROOM INVOLVEMENT TIME

38 Terminology 1. Smoke airborne products of combustion in the air 2. Plume column of hot gases, flames, and smoke rising above a fire 3. Ceiling Jet -a flow of smoke under the ceiling

39 Compartment Fire

40 Compartment Fire Growth Stage room heats up and ceiling layer development

41 Compartment Fire Ceiling Layer Development smoke increases, room heats up, negative pressure in room, two layers

42 Flashover Temperature is about 600 C (1100 F) All materials spontaneously combust Only lasts a few seconds for the transition

43 Flashover

44 Rollover (Flameover) Similar to Flashover Usually in large rooms Fire growth between fuel package usually is not because of the upper gas layer development Also known as Spreadover

45 Full Room Involvement All combustible material in room burns Fire becomes ventilation controlled

46 Ventilation Fires can be controlled by amount of ventilation As a fire grows, needs more oxygen

47 Influence of Ventilation Closed compartment might oxygen starve the fire Openings between compartments allows for fresh oxygen New openings can restart a fire

48 Ventilation Controlled Fire TEMP VENT OPENING TIME

49 Post Full Room Involvement (FRI) Fuel controlled fire Considered d the decay stage Fire burns itself out

50 Backdraft Oxygen regulates the fire Fire slows the burning process (produce large amounts of CO) If a vent opens then fire will combust rapidly (CO combines explosively l with O 2 ) Windows blow out Can be confused with an explosion

51 Backdraft TEMP TIME

52 Fire Modeling Learn Theory vs. Learning Software Better to learn theory Knowing the theory allows you to use any model Knowing the software gives a false sense of modeling

53 Computer Modeling Main types of computer models 1. Zone Models 2. Computational Fluid Dynamics Models (CFD) Field Models 3. Evacuation Models 4. Probabilistic Models Know the limitations

54 The Results Do the results make sense? Is the modeler able to compare the results to empirical correlations? There is no One Answer What is the range of likely answers? Was there a sensitivity analysis run?

55 Modeling Reality Models supplement engineering judgment, they cannot replace it People assume that CFD and zone models are easy to use Reality is it takes a significant amount of work to use such models properly They are easy to misuse

56 Agenda Introduction Short History of Fire Protection Fire Dynamics Fire Protection Systems Egress Case Study - Blessings Tavern Fire

57 Types of Fire Protection Systems There are two main types: Active Passive

58 Active Fire Protection A device or action that receives a stimulus before acting on a fire condition Fire Department Fire Alarm Sprinkler System Standpipe System Clean Agent System Link

59 Passive Fire Protection A building component that remains fixed in the building whether or not a fire condition exists Compartment Enclosure Structural Fire Resistance Fire Attack Route Egress System Link

60 Agenda Introduction Short History of Fire Protection Fire Dynamics Fire Protection Systems Egress Case Study - Blessings Tavern Fire

61 Can you believe real life? This takes place in less than 3 minutes.

62 Egress System A passive fire protection system Interconnected t with: Occupant characteristics Type of occupancy Construction Size of the building Active fire protection systems

63 Egress Computer Models Predict egress time Time = distance/walking speed Could include occupant behavior Should include fire scenario comparison

64 Egress Computer Models People real life reactions are complicated Sight of smoke can change movement Exposure to smoke/heat affect moving Example Models Pathfinder EXITT Evacnet SIMULEX EXODUS

65 Agenda Introduction Short History of Fire Protection Fire Dynamics Fire Protection Systems Egress Case Study - Blessings Tavern Fire

66 Blessings Tavern Fire

67 Blessings Tavern Fire

68 Blessing s Tavern

69

70 Night Of The Fire

71 Night Of The Fire

72 Night Of The Fire

73 Night Of The Fire

74 Night Of The Fire

75 A Few Days Later

76 A Few Days Later

77 A Few Days Later

78 A Few Days Later

79 A Few Days Later

80 A Few Days Later

81 Conclusion Facts of the Inaccuracy - With age comes experience: Code have been reactionary Fire is not an exact science In a perfect world active and passive fire protection installations would all work as intended Preconceived ideas based on common sense is NOT science

82 Conclusion Fire protection is an evolving science. Hi t h h th t t bl History has shown that acceptable practices change over time

83 Conclusion The decisions we make impact lives.

84 Anatomy of a Fire Douglas Nadeau, MSFPE, PE, CFPS, LEED AP President of RAN Fire Protection Engineering, PC Vice President of truvue Inspection Technology Christopher Crivello, MSFPE, PE Fire Protection Project Engineer at RAN Fire Protection Engineering, PC ccrivello@ranfpe.com dnadeau@ranfpe.com