Abstract
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).
Similar content being viewed by others
Abbreviations
- \( c_{p} \) :
-
Specific heat of air (kJ/kg K)
- ɛ :
-
Reduction in critical velocity due to an obstruction
- F :
-
Flow rate (m3/s)
- g :
-
Gravitational acceleration (m/s2)
- H :
-
Tunnel height
- \( \bar{H} \) :
-
Hydraulic tunnel height
- \( L_{b} \) :
-
Backlayering distance (m)
- \( \rho_{0} \) :
-
Ambient density (kg/m3)
- Q :
-
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
References
Svensson S (2000) Fire ventilation. Swedish Rescue Services Agency, Karlstad
Ziesler PS, Gunnerson FS, Williams SK (1994) Advances in positive pressure ventilation: live fire tests and laboratory simulation. Fire Technol 30:269–277
Vaari J, Hietaniemi J (2000) Smoke ventilation in operational fire fighting. Part 2: multi-story buildings. VTT Publications 419, Technical Research Centre of Finland
Svensson S (2001) Experimental study of fire ventilation during fire fighting operations. Fire Technol 37:69–85
Le Corré F (2001) Ventilation dans les incendies appliqué au métro Parisien, ENSAM, Paris
Lougheed GD, McBride PJ, Carpenter DW (2002) Positive pressure ventilation for high-rise buildings. National Research Council Canada, Ottawa
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 March
Ezekoye OA et al. (2005) Effects of PPV attack on thermal conditions in a compartment downstream of a fire. Fire Technol 41:193–208
Kerber S, Walton W (2005) Effect of positive pressure ventilation on a room fire, NISTIR 7213. National Institute of Standards and Technology, Gaithersburg
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 September
Lambert K, Merci B (2014) Experimental study on the use of positive pressure ventilation for fire service interventions in buildings with staircases. Fire Technol 50:1517–1534
McCaffrey BJ, Heskestad G (1976) A robust bidirectional low-velocity probe for flame and fire application. Combust Flame 26(1):125–127
Leader Group, www.leader-group.eu, Octeville-sur-mer, France
Oka Y, Atkinson G (1995) Control of smoke flow in tunnel fires. Fire Saf J 25:305–322
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 35:363–390
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, Germany
Li Y (2010) Study of critical velocity and backlayering length in longitudinally ventilated tunnel fires. Fire Saf J 45:361–370
NBN S21-208-2 (2010) Fire protection in buildings—design and calculation of smoke and heat extraction installations—part 2: covered car park buildings
NFPA 130 (2010) Standard for fixed guideway transit and passenger rail systems
Bartlett N (2012) Optimization of smoke control systems in underground subway stations. IMFSE dissertation, Ghent University
Lambert K (2014) Positive pressure ventilation in underground systems—an experimental and modelling study. IMFSE dissertation, School of Engineering, The University of Edinburgh
Willi J, Madrzykowski D, Weinschenk C (2016) NIST technical note 1938: impact of hose streams on air flows inside a structure
Bryant RA (2009) A comparison of gas velocity measurements in a full-scale enclosure fire. Fire Saf J 44:793–800
Acknowledgements
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.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Lambert, K., Welch, S. & Merci, B. The Use of Positive Pressure Ventilation Fans During Firefighting Operations in Underground Stations: An Experimental Study. Fire Technol 54, 625–647 (2018). https://doi.org/10.1007/s10694-018-0700-8
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10694-018-0700-8