Assessment Of Fire Suppression Capabilities Of Water Mist
-Fighting Compartment Fires with the Cutting Extinguisher-
FIREFIGHT II Mid-term MeetingWednesday 24 – Friday 26 November 2010 in Prague
Pg. Dip. Msc. Fire Safety EngineeringAcademic year 2009/2010
Julien [email protected]
Contents
• Introduction– Msc Fire Safety Engineering– The Master Thesis– Why on the Cutting Extinguisher?
Contents
• Introduction• Background
– Literature review– A Thesis to answer what?– Going further in the study
Contents
• Introduction• Background• Experimental framework
– Enclosure & type of fuel– Instrumentation– Methodology
Contents
• Introduction• Background• Experimental framework• Results
– Water mist behaviour– Fire suppression capabilities– Safety concerns
Contents
• Introduction• Background• Experimental framework• Results• Conclusion
– Publication– Translation in French– Haut-Rhin Fire Service
Introduction
• Msc Fire Safety Engineering– University of Ulster at Jordanstown
Belfast, Northern Ireland
• The Master Thesis– Assessment of the Fire Suppression Capabilities
of Water Mist
• Why on the Cutting Extinguisher?– Previous placement
• Study of the manufacturing, use, and development of the tool
Background
• Literature review
– The Cutting Extinguisher - Concept and Development: Swedish Rescue Services Agency, 1999
– Holmstedt, Göran. An assessment of the Cutting Extinguisher's Capabilities and limitations: Lund University, 1999
– Winkler, Thomas Karlsen & Henrik. Skärsläckaren som röjnings och släckverktyg för fartyg av kolfiberkomposit, 2000
– Olsson, Johannes Bjerregaard & Daniel. Skärsläckaren-experimentella försök och beräkningar, 2007
– Cutting Extinguishing concept-practical and operational use: Swedish Rescue Services Agency, 2010.
Background
• A Thesis to answer what? How this scenario with a focused jet of water and high flow rate, where
the beam is broken up into small droplets, affects the mixing of the fire gases has not so far as known been investigated
the impact of the ventilation openings on the cutting extinguishers ability to extinguish fires
the functioning of the cutting extinguisher in a well controlled fire in relation to various types of and ventilation
the importance for the efficiency of the cutting extinguisher of the water jet being able to break up
Cutting Extinguishing concept-practical and operational use: Swedish Rescue Services Agency, 2010.
Background
• Going further in the study
– Calibration of the water mist generated
– Water mist volumetric behaviour (situation without fire)
– Re-ignition probability
– Possible pressure variations in the compartment
– Consequences of spraying water mist
• Regarding the Fire fighters
• Regarding a potential victim
Experimental framework
• Enclosure & type of fuel– Characteristics & dimensions of the
compartment• 40 feet sea container• Fire area on the bottom• 2.71 m2 openings area to be used
– Type, properties & arrangement
Characteristics & dimensions of the compartment
Experimental framework
• Structure & type of fuel– Characteristics & dimensions of the
compartment
– Type, properties & arrangement• Chipboard panels• 12.8 or 8.4 m2 burning surface• Ceiling, lateral and bottom walls
Type, properties & arrangement
• Instrumentation– Bottle frame
• Every 0.5 m from 2.0 to 10.0 m• 144 bottles for a control surface of 324 cm2
– Thermocouple meshing– Radiometer– Pressure record– Video record
Experimental framework
Bottle frame
Experimental framework
• Instrumentation– Bottle frame– Thermocouple meshing
• 99 TC distributed over 8.8 m length,2.4 m width and 2.4 m height
• Control volume of 0.512 m3
– Radiometer– Pressure record
• 2 transducers– Video record
Temperature, pressure & heat flux
• Instrumentation– Bottle frame– Thermocouple meshing– Radiometer– Pressure record– Video record
Experimental framework
Video record
Methodology
• Scenarios– Location of the Cutting Extinguisher
• Front wall, mid-length, 1.65 m high– Studied parameter
• Experimental protocol– Exploit of the “Bottle frame”– Full scale burnings
Location of the Cutting Extinguisher
Methodology
• Scenarios– Location of the Cutting Extinguisher– Studied parameters
• Volumetric distribution of water• Influence of opening area, fuel surface, and
water flow rate• Experimental protocol
– Exploit of the “Bottle frame”– Full scale burnings
Studied parameters• Fire experiments
Designation of the scenario
Area of the openingsBurning SurfaceWater flow ratePossibles fire scenarios
Fire scenarios
Q = 56 L/min
Sf = 12.8 m2
Ac = 0.192 m2 1Ac = 0.192 m2 2Ao= 2.71 m2 3
Sr = 8.4 m2
Ac = 0.192 m2 4Ao= 2.71 m2 5
Qr = 28 L/min
Sf = 12.8 m2
Ac = 0.192 m2 6Ao= 2.71 m2 7
Sr = 8.4 m2
Ac = 0.192 m2 8
Ao= 2.71 m2 9
Methodology
• Scenarios– Location of the Cutting Extinguisher– Studied parameters
• Experimental protocol– Exploit of the “Bottle frame”– Full scale burnings
Exploit of the bottle frame
Methodology
• Scenarios– Location of the Cutting Extinguisher– Studied parameters
• Experimental protocol– Exploit of the “Bottle frame”– Full scale burnings
Full scale burnings
Results
• Water mist behaviour– Total flooding
• Water content: 44 g/m3
• Volumetric flow rate: 21.2 m3/s• Velocity: 7.13 m/s
– Spray pattern
Total flooding
Total flooding
Results
• Water mist behaviour– Total flooding– Spray pattern
• Inner core + outer ring• Initial diameter: 4.5 °• Break up point at 5.0 m• Widening following an angle of 9.0 °
– Application modes
Spray pattern
Results
• Water mist behaviour– Total flooding– Spray pattern– Application modes
• Spread droplets into the flames• Spread droplets in the smoke layer• Inerting by steam generation• Cool the burning fuel surface• Shield the fuel surfaces not yet involved
Results
• Fire suppression capabilities– Flame tackling time
• Fire extinguished every time• Below 15 seconds regardless to the scenarios• Major effect trough blowing and heat extraction
– Influence of parameters during gas cooling phase
– Re-ignition probability
Flame tackling time
0 200 400 600 800 1000 1200 1400 1600 1800 2000 22000
100
200
300
400
500
600
700
800
900
1000Fire Curves
Scenario 1
Scenario 2
Scenario 3
Scenario 4
Scenario 6
Time (in s.)
Tem
pera
ture
s (in
°C)
Results
• Fire suppression capabilities– Flame tackling time– Influence of parameters during gas cooling
phase• Initial “plateau”• Reducing fuel surface: faster to reach safe level• Increasing opening size: faster to reach safe level• Reducing water flow rate: cooling down more
difficult
– Re-ignition probability
Gas cooling phaseEntire fire development, shown 40 times faster
Gas cooling phaseExtinguishing phase, 4 times faster
Results
• Fire suppression capabilities– Flame tackling time– Influence of parameters during gas cooling
phase– Re-ignition probability
• Likely to occur• No significant temperature or fire rise within 3
min• Limited action of surface cooling• Requires to wet the remaining charring
material
Re-ignition probability
Results
• Safety concerns– Life safety
• Radiation shielding• Remaining of the “oxygen survival layer”• No high temperature or smoke feed back
– Property safety
Life safety• Radiation shielding
Radiation shielding
0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800
-3
-2
-1
0
1
2
3
4
5
6
7
8
9
10
11
12Heat flux variations depending on time
rayonnement
Time (in s.)
Heat
flux
(in
kW/m
2)
Spraying period
Results
• Safety concerns– Life safety
• Radiation shielding• Remaining of the “oxygen survival layer”
– Also mixing & temperature destratification• No high temperature or smoke feed back
– Property safety
Mixing and temperature destratification
Scenario n°6
Results
• Safety concerns– Life safety
• Radiation shielding• Remaining of the “oxygen survival layer”• No high temperature or smoke feed back
– Property safety
Life safety
Results
• Safety concerns– Life safety– Property safety
• No water damage• No over pressure
Property safety
Conclusion
• Publication• Translation in french• Haut-Rhin Fire & Rescue Services• FIREFIGHT?
Thank you for listening
Questions?