Fire Technology

, Volume 54, Issue 3, pp 625–647 | Cite as

The Use of Positive Pressure Ventilation Fans During Firefighting Operations in Underground Stations: An Experimental Study

  • K. LambertEmail author
  • S. Welch
  • B. Merci


Positive pressure ventilation (PPV) fans are widely used by the fire service during firefighting operations in buildings. Fans are positioned to create a flow through the enclosure. This flow can remove the smoke after the fire or affect the direction of the smoke to support firefighting operations. In subway stations, it is less common to use PPV fans. Here, 106 full-scale tests with up to four fans have been performed in a training building that represents a subway station. The fans were used as extraction fans. The generated flow through the subway station has been measured. The critical velocity for a hypothetical tunnel (W × H: 3.17 × 4.15 m) attached to the subway station has been calculated as 2.37 m/s. Reaching the critical velocity has been used as criterion for ‘success’. All combinations with four fans exceed this velocity, supporting the idea that the fans could be used to facilitate a firefighting operation. The location of the fans was varied. Combinations with three fans on the platform and one at the top of the staircase performed better than combinations with two fans on the platform, one on the landing and one at the top of the staircase. There is an optimum value for the distance between the fans on the platform and the first step of the staircase. This value depends on the angle of inclination of the fans. The fans were not capable of creating a flow that exceeded the critical velocity in the station itself (L × W × H: 60 × 7.15 × 4.53 m). However, a velocity of 2.40 m/s corresponds to a flow rate that will limit the backlayering distance in the station to 15 m. This was only achieved by tests with four fans (three on the platform and one at the top of the staircase).


Positive pressure ventilation PPV Fire service intervention Full-scale experiments Subway stations 

List of symbols

\( c_{p} \)

Specific heat of air (kJ/kg K)


Reduction in critical velocity due to an obstruction


Flow rate (m3/s)


Gravitational acceleration (m/s2)


Tunnel height

\( \bar{H} \)

Hydraulic tunnel height

\( L_{b} \)

Backlayering distance (m)

\( \rho_{0} \)

Ambient density (kg/m3)


Heat release rate (kW)

\( Q^{*} \)

Dimensionless heat release rate

\( T_{0} \)

Ambient temperature (K)

\( V_{cr} \)

Critical velocity (m/s)

\( V_{ctr} \)

Critical velocity in the obstructed tunnel (m/s)

\( V_{cr}^{*} \)

Dimensionless critical velocity

\( V^{*} \)

Dimensionless ventilation velocity



This paper is a summary of the thesis of Karel Lambert [21], performed in the context of the International Master of science in Fire Safety Engineering (IMFSE) at the universities of Ghent, Lund and Edinburgh. The first author strongly acknowledges the financial support from EACEA during his studies in IMFSE, the material support of the Brussels fire department, the Frankfurt Fire Department and Ghent University. The authors also acknowledge Associate Professor Stefan Svensson (Lund University) for their valuable comments during the research. Finally, the authors thank Nathalie Van Moorter for the illustrations in this paper.


  1. 1.
    Svensson S (2000) Fire ventilation. Swedish Rescue Services Agency, KarlstadGoogle Scholar
  2. 2.
    Ziesler PS, Gunnerson FS, Williams SK (1994) Advances in positive pressure ventilation: live fire tests and laboratory simulation. Fire Technol 30:269–277CrossRefGoogle Scholar
  3. 3.
    Vaari J, Hietaniemi J (2000) Smoke ventilation in operational fire fighting. Part 2: multi-story buildings. VTT Publications 419, Technical Research Centre of FinlandGoogle Scholar
  4. 4.
    Svensson S (2001) Experimental study of fire ventilation during fire fighting operations. Fire Technol 37:69–85CrossRefGoogle Scholar
  5. 5.
    Le Corré F (2001) Ventilation dans les incendies appliqué au métro Parisien, ENSAM, ParisGoogle Scholar
  6. 6.
    Lougheed GD, McBride PJ, Carpenter DW (2002) Positive pressure ventilation for high-rise buildings. National Research Council Canada, OttawaGoogle Scholar
  7. 7.
    Ezekoye OA, Hal CH, Nicks R (2003) Positive pressure ventilation attack for heat transport in a house fire. In: The 6th ASME-JSME thermal engineering joint conference, 16–20 MarchGoogle Scholar
  8. 8.
    Ezekoye OA et al. (2005) Effects of PPV attack on thermal conditions in a compartment downstream of a fire. Fire Technol 41:193–208CrossRefGoogle Scholar
  9. 9.
    Kerber S, Walton W (2005) Effect of positive pressure ventilation on a room fire, NISTIR 7213. National Institute of Standards and Technology, GaithersburgCrossRefGoogle Scholar
  10. 10.
    Ezekoye OA, Svensson S, Nicks R (2007) Investigating positive pressure ventilation. In: Proceedings of 11th international fire science & engineering conference (Interflam’07), Interscience communications, London, 3–5 SeptemberGoogle Scholar
  11. 11.
    Lambert K, Merci B (2014) Experimental study on the use of positive pressure ventilation for fire service interventions in buildings with staircases. Fire Technol 50:1517–1534CrossRefGoogle Scholar
  12. 12.
    McCaffrey BJ, Heskestad G (1976) A robust bidirectional low-velocity probe for flame and fire application. Combust Flame 26(1):125–127CrossRefGoogle Scholar
  13. 13.
    Leader Group,, Octeville-sur-mer, France
  14. 14.
    Oka Y, Atkinson G (1995) Control of smoke flow in tunnel fires. Fire Saf J 25:305–322CrossRefGoogle Scholar
  15. 15.
    Wu Y, Bakar M (2000) Control of smoke flow in tunnel fires using longitudinal ventilation systems—a study of the critical velocity. Fire Saf J 35:363–390CrossRefGoogle Scholar
  16. 16.
    Fathi T (2010) New perspectives on the critical velocity for smoke control. In: Proceedings: 4th international symposium on tunnel safety and security, Frankfurt am Main, GermanyGoogle Scholar
  17. 17.
    Li Y (2010) Study of critical velocity and backlayering length in longitudinally ventilated tunnel fires. Fire Saf J 45:361–370CrossRefGoogle Scholar
  18. 18.
    NBN S21-208-2 (2010) Fire protection in buildings—design and calculation of smoke and heat extraction installations—part 2: covered car park buildingsGoogle Scholar
  19. 19.
    NFPA 130 (2010) Standard for fixed guideway transit and passenger rail systemsGoogle Scholar
  20. 20.
    Bartlett N (2012) Optimization of smoke control systems in underground subway stations. IMFSE dissertation, Ghent UniversityGoogle Scholar
  21. 21.
    Lambert K (2014) Positive pressure ventilation in underground systems—an experimental and modelling study. IMFSE dissertation, School of Engineering, The University of EdinburghGoogle Scholar
  22. 22.
    Willi J, Madrzykowski D, Weinschenk C (2016) NIST technical note 1938: impact of hose streams on air flows inside a structureGoogle Scholar
  23. 23.
    Bryant RA (2009) A comparison of gas velocity measurements in a full-scale enclosure fire. Fire Saf J 44:793–800CrossRefGoogle Scholar

Copyright information

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

Authors and Affiliations

  1. 1.Brussels Fire DepartmentBrusselsBelgium
  2. 2.The University of EdinburghEdinburghUK
  3. 3.Department of Flow, Heat and Combustion MechanicsGhent University – UGentGhentBelgium

Personalised recommendations