Design Fires for Smoke Control

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Design Fires for Smoke Control

• Dr. John H. Klote PE
• Fire and Smoke Consulting
• john_at_SmokeControlExpert.com
• www.SmokeControlExpert.com

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Learning Objectives

• Provide an understanding of fire growth,
  flashover, fully developed fire and fire decay.
• Provide an overview of the basic concepts of
  developing design fires for smoke control
  systems.

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• Extensive Treatment of All Aspects of Smoke
  Control
• For more information about design fires, see
  Chapter 5 Fire Physics Design Fires

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Design Fires

• Used for Atrium Smoke Control and Tenability
  Systems
• IBC
• No Prescribed Design Fires
• Requires Analysis of Design Fires
• Many Engineers New to Design Fires
• This Talk
• Overview of Analysis of Design Fires
• Focus on Highlights

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UK Information on Design Fires

• Industrial Warehouse (not high racked) -1990
  Smoke Ventilation Association Guide
• Sprinklered Steady Fires - 3m x 3m to 9m x 9m.
• Unsprinkleres Steady Fires 2 Times as Big
• Steady Fires in Car Parks BS 7346-7
• Guidance for Offices Hotels BS 7346-4 and 5
  and in BR368
• General Information on Specific Objects
• BS 7974 (UK fire engineering standard)
• BRE design fires database CD

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Design Fires

• Normally Most Important Property - Heat Release
  Rate (HRR)
• Other Properties (toxic gases, reduced
  visibility, etc.) - Tenability Systems
• For simplicity - Only Discuss HRR
• HRR of a Design Fire
• Steady
• Unsteady
• Steady HRR Peak of Unsteady HRR

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Fully Developed Fire

• Called Ventilation Controlled Fire
• Room with One Opening
• HRR Controlled by Opening Size HRR Equation

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HRR Measurement

• Oxygen Consumption Calorimeters
• HRR per unit O2 Consumed Almost Constant (13.1
  MJ per kg of oxygen 6)
• Open Air Calorimeter
• Room Calorimeter

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Design Fires

• Normal Fuels - Objects Planned for Space
• Transient Fuels - In a Space Temporarily
• Examples Trash, Stacked Wood Pallets, Furniture
  After Delivery, etc.
• Atrium Fires
• Normal Transient Fuels
• No Benefit of Sprinklers (Ceilings gt 35 45 ft)
• Transient Fuels Suggest Min. 2000 Btu/s
• Non-Atrium Fires
• Normal Transient Fuels
• Fires w/ Axisymmetric Plume CFAST
• Shielded Fires (NIST NRCC Models)

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Questions?
Dr. John H. Klote PE john_at_SmokeControlExpert.com w
ww.SmokeControlExpert.com