Smoke and Heat Venting in Sprinklered Facilities

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Smoke and Heat Venting in Sprinklered Facilities

• Dr. Craig Beyler

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Value of SHVs in Sprinklered Facilities

• Improved visibility (and reduced heat and toxic
  gases)
• life safety/egress
• firefighter access
• Eliminates the need for manual venting by the
  fire department
• Reduced heat and smoke damage

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Concerns with SHVs in Sprinklered Facilities

• Potential negative impact on sprinkler
  performance
• Cost effectiveness

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Smoke and Heat Venting
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Sprinklers Alone
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Combined Sprinklers and Vents Ideal Scenario
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State of Knowledge SHVs in Sprinklered
Facilities 1950s to the present

• Full-scale fire tests
• Reduced-scale fire tests
• Mathematical modeling

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Sprinkler/Vent Fire Tests

• 1955 Armor Research Foundation reduced scale
  testing (18), pool fires
• 1956 FM, 120 X 60, spray fires
• UL 1964, wood cribs, cardboard, and plastics
• 1974 FM Reduced Scale (112.5), 20 X 16,
  vertical tri-wall cardboard array, ganged spray
  nozzles

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Sprinkler/Vent Fire Tests

• 1977 IITRI, 75 X 25, pallet fires
• 1992 FRS/Colt, 150 X 60, controlled pool fire
  (Ghent) (ganged vent ops)
• 1997 NFPA RF, 100 X 100, UL ventilated
  facility, - spray fires (growing fires up to 10
  MW)- rack commodity fires (20 high Group A
  Plastics in double row racks)

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Findings

• Vents improve visibility and reduce exposure to
  smoke and heat (1-6)
• Thermally activated vents do not open in large
  numbers so that manual operation of vents by FD
  is generally needed as well (3-5, 7)
• Venting does not interfere with sprinkler
  performance (2-7)
• Full scale sprinkler tests with suppressible
  fuels are not reproducible (5,7)
• FDS can predict well the thermo-fluidic
  environment and sprinkler operation, but not
  suppression (7)

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FDS Prediction of Sprinkler Operations

• First ring operation time 15
• Second ring operation time 25

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FDS Simulations of Performance of SHVs in
Sprinklered Facilities

• Goal Evaluate venting performance and effect on
  sprinkler operations
• Findings 1. Venting had no effect on sprinkler
  operations2. Venting improved smoke
  conditions3. Additional vent area is beneficial

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Plan View of the Modeled Building
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No Smoke and Heat VentsVisibility Distance at
600 sec.
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Four S HVs Operating Visibility Distance at
600 sec.
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16 S HVs Operating Visibility Distance at 600
sec.
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Ganged Vent Operation Concept

• Operate all vents within a sprinkler system area
  (40,000 sq ft) one minute after first sprinkler
  operation using a water flow alarm device
• Approach supports remote manual operation of
  vents by FD as well
• Model with FDS to evaluate system performance

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Computational Domain(two 40,000 sq ft sprinkler
systems)
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Smoke Remaining in the Building
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Visibility Distance (ft) at 10 Minutes
Without smoke and heat vents and without draft
curtains
With smoke and heat vents and without draft
curtains
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Visibility Distance (ft) at 15 Minutes
Without smoke and heat vents and without draft
curtains
With smoke and heat vents and without draft
curtains
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FDS Modeling Findings

• Ganged vent operation concept is highly effective
  in mitigating heat and smoke hazards
• Ganged vent operation has no impact on sprinkler
  effectiveness

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Path Forward

• Incorporate new findings in NFPA 204, Standard
  for Smoke and Heat Venting in Fall 2009 cycle
• Propose adoption of NFPA 204 in IBC in next
  edition (as has already been done with NFPA 92B
  (atria etc.))