Design Fires for Smoke Control
Dr. John H. Klote PE
Fire and Smoke Consulting
[email protected]
www.SmokeControlExpert.com
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.
• Extensive Treatment of
All Aspects of Smoke
Control
• For more information
about design fires, see
Chapter 5 “Fire Physics
& Design Fires”
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
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
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
Fully Developed Fire
• Called “Ventilation Controlled Fire”
• Room with One Opening
– HRR Controlled by Opening Size – HRR
Equation
Q  1260 Aw H
1/ 2
w
where
Q= HRR (kW)
2
Aw = area of opening (m ),
Hw = height of opening (m).
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
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 > 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)
Questions?
Dr. John H. Klote PE
[email protected]
www.SmokeControlExpert.com