Advertisement

Fire Technology

, Volume 55, Issue 1, pp 285–305 | Cite as

Experimental Study of Gas Cooling During Firefighting Operations

  • Stefan SvenssonEmail author
  • Matthias Van de Veire
Article
  • 112 Downloads

Abstract

Gas cooling is a technique used by firefighters to reduce the dangers posed by the hot smoke in enclosure fires and, to thereby approach a fire while keeping their escape route safe. The technique includes bursts of water from a fog nozzle producing small droplets into the hot gases. The purpose of this work was to experimentally investigate the effects of gas cooling. A total of 44 tests were conducted in an 1800 × 1200 × 1200 mm room with an added fire room sizing 1200 × 760 × 1200 mm. A gas burner with a RHR of approximately 90 kW was used as a heat source. Four different nozzles were used, differing in droplet size, flow, and spray pattern. Also, reach, number of bursts and open time of the nozzles varied between tests. In this paper, six of the test with the most important and pronounced results were used for comparison. Conclusions from the tests included that nozzles producing droplets with a median diameter of approximately 500 µm delivered in multiple short burst with time in between bursts kept as short as possible were most effective for gas cooling. However, overall in this experimental setup taking all droplets sizes into consideration, a single longer burst performed slightly better than several short bursts as a similar temperature reduction is achieved in 1/3rd of the time of 5 short bursts and gases are cooled over a larger part of the room. The volume of the smoke was not observed to change significantly due to gas cooling.

Keywords

Gas cooling Firefighting Nozzle Fire service 

List of Symbols

a

Proportion of water that vaporizes

Ao,x

Area of opening to compartment x

At,x

Total enclosure area of compartment x

b

Proportion of water that vaporizes due to the heat of the smoke

cp

Specific heat capacity (J/kg K)

cp,sm

Specific heat capacity of smoke (33.2 J/mol K)

cp,st

Specific heat capacity of steam (41.2 J/mol K at 1000 K)

cp,w

Specific heat capacity of water (75.31 J/mol K)

d0

Initial droplet diameter (m)

H0,x

Height of opening to compartment x

k

Conductivity of smoke (W/mK)

lmax

Maximum fall length of a droplet (m)

Lv

Heat of vaporization (kJ/kg)

Lv

Heat of vaporization/latent heat (J/kg)

Lv,w

Latent heat of water (2260 J/g)

m

Mass (kg)

Mw

Molecular weight of water (18 g/mol)

n

Molar amount

Nu

Nusselt number

Q

Energy (J)

T

Temperature (K)

tlife

Time for a droplet to evaporate (s)

v

Droplet falling velocity (m/s)

ρ

Density (kg/m3)

RHR

Rate of heat release

Subscripts

sm

Smoke

sm + st

Smoke + water

w

Water

Notes

References

  1. 1.
    Lambert K (2012) Gas cooling: a new approach. www.cfbt-be-com. Accessed 16 Aug 2016
  2. 2.
    Grimwood P (1994) A comparison of 3D water-fog versus straight streams, using “burst & pause” cycles, to cool & inert dangerous fire gases in the overhead of a compartment fire. http://www.highrisefirefighting.co.uk. Accessed 16 Aug 2016
  3. 3.
    Hartin E (n.d.) 3D firefighting|compartment fire behavior training. http://cfbt-us.com/wordpress/?tag=3d-firefighting. Accessed 16 Aug 2016
  4. 4.
    Lambert K, Baaij S (2015) Fire dynamics: technical approach, tactical application. Sdu Uitgevers, The HagueGoogle Scholar
  5. 5.
    Grimwood P, Desmet K (2003) Tactical firefighting, a comprehensive guide to compartment firefighting & live fire training (CFBT). www.eurofirefighter.com. Accessed 19 Oct 2017
  6. 6.
    Grimwood P, Hartin E, McDonough J, Raffel S (2005) 3D fire fighting training, techniques and tactics. Fire Protection Publications, StillwaterGoogle Scholar
  7. 7.
    Hartin E (2010) Gas cooling. http://cfbt-us.com/wordpress/?p=1212. Accessed 16 Aug 2016
  8. 8.
    Svensson S (2002) The operational problem of fire control. Lund University. In: SFPE handbook of fire protection engineering, 5th edn. SpringerGoogle Scholar
  9. 9.
    Särdqvist S (2002) Water and other extinguishing agents. Swedish Rescue Services Agency, KarlstadGoogle Scholar
  10. 10.
    Svensson S (2002) The operational problem of fire control. Lund University, LundGoogle Scholar
  11. 11.
    Hartin E (2010) Gas cooling: part 5. http://cfbt-us.com/wordpress/?p=1299. Accessed 18 Jan 2018
  12. 12.
    Herterich, O. (1960). Wasser al Löschmittel: anwendung und technik im Brandschutz. Dr Alfred Hüthig Verlag GMBH, HeidelbergGoogle Scholar
  13. 13.
    Alageel S (1999) Mitigation of compartment jet fires using water sprays. The University of Sheffield, SheffieldGoogle Scholar
  14. 14.
    ISO 9705, Reaction to fire test: room corner test for wall and ceiling lining productsGoogle Scholar
  15. 15.
    Karlsson B, Quintiere JG (2000) Enclosure fire dynamics. CRC Press LLC, RatonGoogle Scholar
  16. 16.
    Data sheet cembrit multi force. http://www.cembrit.se. Accessed 17 Aug 2016
  17. 17.
    Spraying Systems Co. www.spray.com. Accessed 17 Aug 2016
  18. 18.
    Van de Veire M. (2016) Studies on the importance of firefighters’ gas cooling (report 5515). Department of Fire Safety Engineering ,LundGoogle Scholar
  19. 19.
    Akron Force data sheet, (Measurement report, Ref 971428X5, 1998), Akron Brass Company, Wooster, OhioGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Swedish Civil Contingencies Agency (MSB)RevingeSweden
  2. 2.Brussels Fire DepartmentBrusselsBelgium

Personalised recommendations