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Fire growth: No sprinklers

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Title: Fire growth: No sprinklers


1
Fire growth No sprinklers
2
Fire growth Sprinklers present
2
Workbook Page
3
Why Fire Sprinklers?
  • 80 of fire deaths occur in the home
  • Low probability, high consequence event
  • Over 4,000 people die each year in home fires
  • millions in property damage
  • Less than 2 of homes contain sprinklers

4
Residential sprinkler benefits
Life safety
5
Residential sprinkler benefits
Property safety
Conservation
Environmental impact
FF safety
Housing density
Demand on FD
6
Causes of house fires ()
10
25
15
13
22
15
7
Who Is Most At Risk In A Fire?
  • Sleeping occupants
  • Small children and the elderly
  • Twice as likely to die as able-bodied adults

8
What Is Flashover?
  • When ceiling temp reaches 1,200 F
  • Bottom of smoky layer erupts into flame
  • Everything combustible ignites at once
  • Can take as little as five minutes

9
Heat Spread by Convection
10
Heat Spread by Convection
11
Most victims in post-flashover fires are remote
from the room of origin
12
Residential Sprinklers Demand on Resources
  • Water
  • 9-12 GPM v. 200 GPM per line.
  • Apparatus personnel
  • Fewer critical tasks fewer resources.
  • Organization
  • Can be EMS-oriented v. suppression-oriented.

13
Critical fireground task
  • A task that must be performed simultaneously, or
    in a highly coordinated manner, with other tasks.
  • Examples of critical tasks
  • Attack line and ventilation
  • Attack line and water supply

14
Critical Fireground Tasks
  • Task Personnel Assignment
  • Attack 2 1st
    engine
  • S R 2 Ladder
    Co.
  • Ventilation 2 As
    assigned
  • Backup line 2 2nd engine
  • Safety 1 As
    assigned
  • Pump oper. 2 Each engine
  • Water supp. 1 2nd engine
  • Command 1 District
    chief

15
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18
Sprinkler v. manual suppression
  • 30-90 seconds after flames
  • 13 GPM _at_ 10 PSI
  • Very little has burned
  • Room of origin still tenable to life
  • Operates automatically
  • 8-15 minutes after report
  • 200 GPM _at_ 100 PSI
  • A lot has burned
  • Entire home untenable to life
  • Someone needs to call fire department

19
Sprinkler v. fire department
  • Sprinkler
  • Operates whether you can take action or not
  • Elderly, bedridden, children
  • Operates whether you are there or not
  • Asleep, in another room, in yard, away
  • Fire department
  • Firefighters cant respond until someone calls
  • Fire can burn unnoticed until it breaks out of
    house

20
Why sprinklers?
  • Builders build safe homes then people move in
  • Houses dont catch fire, contents do
  • Contents loaded with synthetic material
  • Burn twice as hot, twice as fast
  • Homes are tight for energy

21
Why FDs want sprinklers
  • Cant respond in time to save lives
  • Content fires go to flashover in 5 minutes or
    less
  • Occupants start dying halfway to flashover
  • Occupants who cant get out under own power twice
    as likely to die
  • The young, elderly

22
Smoke alarm limits
  • In house fire where deaths occurred, over 40
    percent of the homes had working smoke detectors
  • Occupants often disable smoke alarms to prevent
    nuisance alarms

23
Sprinkler effectiveness
  • Smoke detectors by themselves less than 50
    effective
  • Smoke detectors sprinklers increase survival
    rates to 97
  • Based on long-term studies in Napa CA, Prince
    Georges County MD, Scottsdale AZ

24
Why sprinklers are effective
  • Quick acting (30-60 seconds after flames visible)
  • Fire is small and containable
  • Stop spread of smoke and flame before flashover
  • Control fire with 10-15 GPM v. 200 GPM from fire
    hose

25
Sprinkler experience
  • Zero lives lost in sprinklered homes
  • Scottsdale, AZ
  • Napa, CA
  • Prince Georges County, MD
  • Property damage (including water damage) nine
    times less
  • Fire departments handle with fewer stations and
    firefighters

26
Before 13D
  • NFPA 13 was the only standard
  • Categorizes buildings by hazard class
  • Fire load, rate of heat release, peak heat
    release
  • Uses area v. density to determine water flow
  • As hazard class increases, density and coverage
    area increase
  • Higher hazard more GPM, more sprinklers
  • Additional gallonage for fire hoses

27
NFPA 13 Area/Density curves
28
Density and area coverage
  • Function of orifice size and pressure.
  • Orifice size indicated by K factor.
  • Examples - 3.0, 3.9, 4.2, 5.6.
  • The higher the K factor, the larger the orifice.

29
Lower pressure smaller area
30
Higher pressure larger area
31
Use of higher pressure
  • Sprinklers with the same orifice size can cover
    wider areas with the same density
  • Reliable RES 16, 3.0 K factor
  • 9 GPM over 12 x 12 area at 9 PSI
  • 10 GPM over 14 x 14 area at 11.1 PSI
  • Both supply .04 GPM per sq. foot

32
Use of larger orifices
  • Compared to a head with a smaller K factor, one
    with a larger K factor supplies a higher density
    to the same area.
  • 3.0 for 14x14 area flows 10 GPM at 11.1 PSI.
  • 3.9 for 14x14 area flows 12 GPM at 9.5 PSI.

33
Hydraulically most remote
  • The hydraulically most demanding
  • At the minimum required flow, the sprinkler that
    causes the highest drop in pressure from the
    street
  • Not the geographically most remote on gridded
    systems
  • Water enters grid at different points

34
NFPA 13D
  • Installation of Sprinkler Systems in One- and
    Two-Family Dwellings and Manufactured Homes

35
NFPA 13Ds beginnings
  • America Burning published in 1973
  • US leads in fire deaths.
  • Most fire deaths occur in homes.
  • NFPA 13 committee formed residential
    sub-committee to investigate sprinkler protection.

36
Format of 13D
  • 1 - General information.
  • 2 - Water supply.
  • 3 - System components.
  • 4 - System design.
  • 5 - Limited area dwellings.
  • 6 - Referenced publications.
  • App. A - Explanatory material
  • App. B - Referenced publications.

37
13D objectives
  • Limit maximum ceiling temp to 600F.
  • Limit temp at 5 3 to 200F.
  • Prevent flashover and keep room of origin tenable
    to life for 10 minutes.
  • Attain objectives with no more than two
    sprinklers operating, with density of .04 GPM/sq.
    foot.
  • No minimum area requirement.

38
Committee recommendations
  • System can be slightly less reliable, with fewer
    operational features, and be effective
  • Must be substantially less expensive
  • Primary goal life safety
  • Secondary goal property safety
  • Should control fire for sufficient escape time
    10 minutes

39
Recommendations
  • Piping, components, hangers must be compatible
    with residential construction techniques
  • Combined sprinkler/plumbing systems are
    acceptable from a fire protection standpoint
  • Sprinklers can be omitted in areas of low
    incidence of fire deaths

40
First edition of 13D in 1975
  • Based on relatively limited scientific
    understanding of residential fires and how
    sprinklers should protect against them
  • Applied technology that was applicable to
    property protection or commercial, industrial
    occupancies
  • Was not cost-effective but spurred research and
    development

41
Full scale tests
  • Discharge rates
  • Spray patterns
  • Response sensitivity
  • Design criteria
  • Ability to maintain tenability to life for escape
    time

42
Goal Tenability in room of origin
  • Carbon monoxide concentration
  • 3000 PPM
  • Temperature at breathing level
  • 200F
  • Oxygen depletion

43
1980 edition
  • Based on better understanding of residential
    fires
  • Had a new class of sprinkler
  • Based on different method for calculating minimum
    water flow

44
Criteria for residential sprinklers
  • Prevent flashover.
  • Turning point in fire for victims, firefighters
  • Maintain 200oF at eye level
  • Temperature is survivable near the floor
  • 150oF of moist air will prevent breathing
  • Control fire with one or two sprinklers
  • Allows smaller water supply

45
What Does NFPA 13D Say About Water Supply?
  • Must have enough to meet demand for 10 minutes
  • Acceptable are
  • Connections to a reliable waterworks system
  • An elevated tank
  • A pressure tank
  • A stored water source with an
    automatically operated pump

46
Sprinkler incentives
  • Narrower streets
  • Smaller setbacks
  • Smaller water mains
  • Fewer fire hydrants
  • Fewer fire stations

47
WHAT LIES AHEAD
48
10-20 GPM v. 200 GPM
49
Fire threat, 1-2 family homes
  • Sleeping occupants
  • Small children, elderly and no special exit
    arrangements
  • Cooking facilities
  • Smoking
  • Unprotected vertical openings

50
House fires
  • A low probability event, but a high-consequence
    event
  • A reasonably expected risk in this community

51
Flashover is the enemy
  • Flashover - all exposed surfaces in room ignite
    almost simultaneously
  • Flashover description - flames out the door of
    room of origin
  • Time to flashover dictated by rate of heat
    release
  • Synthetics burn twice as hot, twice as fast

52
Time to flashover
  • Measured from time of flaming stage
  • A large portion of fires go to flaming stage
    quickly
  • Smoldering stage nearly always progresses to
    flaming
  • May not produce much hot smoke until shortly
    before flaming

53
Fire cause and time to flashover
  • Unattended cooking Very quickly
  • (25-30 )
  • Playing with matches Very quickly
  • (13 )
  • Arson (15) Very quickly
  • Smoldering cigarette Minutes-hour
  • (20-25)
  • Heating (15) Minutes
  • Electrical (10-12) Minutes-hour

54
Most victims in post-flashover fires are remote
from the room of origin
55
Home fires by victim location extent of flame
damage
56
Residential Sprinkler Characteristics
  • Fast response
  • 30-60 seconds v. 120-180 seconds for commercial
    sprinklers
  • Discharge pattern
  • Hits wall at 12 below ceiling
  • Prevents flashover in room of origin
  • Reduces number of critical fireground tasks

57
characteristics.
  • Responds before room of origin becomes untenable
    to human life
  • Tenability
  • Eye-level temp gt 150oF, moist air
  • CO gt 3000 ppm
  • Smoke gt .5 Optical Density/m

58
House fire at 4842 Oak Street
  • Two-story home
  • Fire in kitchen
  • Source - Electric heater
  • Material ignited - synthetic-lined drapes, spread
    to cabinets and cupboards

59
Residential fires
  • 23 of fires
  • 80 of fire deaths
  • 75 of fire injuries

60
Events after discovery
  • Family sleeping in upstairs bedrooms
  • Parents awakened (maybe smoke alarm).
  • Mother saw incipient fire, called 911
  • Smoke, heat blocked mother from returning
    upstairs, she escaped through front door
  • Father rescued two sons, could not reach third
  • One fatality, four injured

61
Fire growth
  • Flashover occurred 4 minutes after flaming stage
  • Untenable in 2 minutes
  • Fire department arrived 4-5 minutes after call
  • Victim died of CO poisoning

62
Witness statements confirm model results
  • Mothers description
  • Saw curtains on fire
  • Grabbed extinguisher, fire too large
  • Went to living room to call 911
  • Tried to go back upstairs, stopped by smoke/heat
  • Neighboring firefighters description
  • Saw fire in kitchen as he started across street
  • In seconds, flames were out front door

63
If sprinklers had been installed
  • No sprinkler
  • Untenability in 123 seconds (smoke, heat, O2)
  • Flashover in 4 minutes, 8 seconds
  • Sprinkler present
  • Sprinkler operated in 68 seconds
  • Ceiling temp 250F
  • Not enough smoke, heat, CO to make room untenable
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