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Fire growth: No sprinklers

Fire growth: No sprinklers. Fire growth: Sprinklers present. 2. Workbook Page. 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

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Fire growth: No sprinklers

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

  16. 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 can’t respond until someone calls Fire can burn unnoticed until it breaks out of house Sprinkler v. fire department

  17. Why sprinklers? • Builders build safe homes – then people move in • Houses don’t catch fire, contents do • Contents loaded with synthetic material • Burn twice as hot, twice as fast • Homes are tight for energy

  18. Why FD’s want sprinklers • Can’t respond in time to save lives • Content fires go to flashover in 5 minutes or less • Occupants start dying halfway to flashover • Occupants who can’t get out under own power twice as likely to die • The young, elderly

  19. 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

  20. 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

  21. 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

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

  23. 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

  24. NFPA 13 Area/Density curves

  25. 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.

  26. Lower pressure = smaller area

  27. Higher pressure = larger area

  28. 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

  29. 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.

  30. 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

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

  32. NFPA 13D’s 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.

  33. 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.

  34. 13D objectives • Limit maximum ceiling temp to 600°F. • Limit temp at 5’ 3” to 200°F. • 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.

  35. 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

  36. 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

  37. 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

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

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

  40. 1980 edition • Based on better understanding of residential fires • Had a new class of sprinkler • Based on different method for calculating minimum water flow

  41. 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

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

  43. WHAT LIES AHEAD

  44. 10-20 GPM v. 200 GPM

  45. Fire threat, 1-2 family homes • Sleeping occupants • Small children, elderly and no special exit arrangements • Cooking facilities • Smoking • Unprotected vertical openings

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

  47. 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

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