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![Figure 2. Conical air jet produced by PPV [14]](profile/Daniel-Madrzykowski/publication/268205028/figure/fig1/AS:295442165321735@1447450309615/Conical-air-jet-produced-by-PPV-14_Q320.jpg)
Citations
... Three sampling probes positioned 0.3 m, 1.2 m, and 2.1 m below the ceiling were installed at the location marked by the green hexagon in Fig. 6 . The total expanded uncertainty of the pressure measurements is estimated to be ± 10 % [6] . ...
There exists a variety of specialized fire dynamics routines, zone fire models, and field fire models. Many of these heuristics and correlations rely on experimental data from fires fueled by gas burners or liquid pool fires and have had minimal, if any, validation against data from fires with solid, more complex fuels, such as upholstered furniture. One hundred and twenty fire experiments were conducted inside a compartment that contained a single ventilation opening in the form of a doorway that was either open or closed for the entirety of each experiment. The fires were fueled by natural gas burners and upholstered furniture items. The compartment was instrumented throughout with thermocouples, oxygen sampling probes, heat flux gauges (total and radiative), pressure transducers, and bi-directional probes. Additionally, heat release rate data were collected during open door experiments with fires larger than 100 kW. This experimental series was designed to better quantify the repeatability of and differences between natural gas burner and upholstered furniture fuels and to provide new validation cases for the fire modeling community.
... Positive pressure ventilation is used to remove heat and smoke or prevent heat and smoke from entering the structure's stairwell and public hallways. Positive pressure ventilation is being applied by firefighters in smaller buildings to control fire-driven airflow by exerting pressure from the front door and venting the building via a strategic exit opening [80][81][82]. ...
This work provides a detailed overview of existing investigations into the fire–wind interaction phenomena. Specifically, it considers: the fanning effect of wind, wind direction and slope angle, and the impact of wind on fire modelling, and the relevant analysis (numerical and experimental) techniques are evaluated. Recently, the impact of fire on buildings has been widely analysed. Most studies paid attention to fire damage evaluation of structures as well as structure fire safety engineering, while the disturbance interactions that influence structures have been neglected in prior studies and must be analysed in greater detail. In this review article, evidence regarding the fire–wind interaction is discussed. The effect of a fire transitioning from a wildfire to a wildland–urban interface (WUI) is also investigated, with a focus on the impact of the resulting fire–wind phenomenon on high- and low-rise buildings.
... Stephen Kerber (UL) published many papers, presentations and reports about wind-driven fires, which are very beneficial for understanding of wind-driven fires and extinguishing procedures under these conditions -e.g. Fire-fighting Tactics under Wind Driven Conditions [41]. ...
Foreword
This document is focused on problematic of firefighting in bio‐based buildings. It collects experience, information, knowledge and results from experiments which can be seen as helpful for firefighters to better understand structural fires with bio‐based materials and as well as for incident commanders with decision makings. As every fire is different, information might not be applicable for all cases and every decision depends on specific conditions various than described in this document.
Acknowledgments
Heartfelt thanks to Stefan Svensson from Myndigheten för samhällsskydd och
beredskap, Lars Brodin and Ville Bexander from Brandskyddsföreningen Sverige, Byggnadstekniska Byrån, Barry Levis, Daniel Olsson from Storstockholms brandförsvar, Vincenzo Puccia from Corpo Nazionale dei Vigili del Fuoco, Sami Kerman from Suomen Palopäällystöliitto, Andrew Macilwraith from Cork County Council, Peter McBride from City of Ottawa and Francisco Javier Elorza from Provincial Council of Bizkaia for collaboration help, consultancy and providing valuable information. The authors gratefully acknowledge the European COST Action FP1404 on Fire safe use of bio‐based building products.
... The bulkhead door (or the roof door) was closed to maintain desired pressure levels [8,12]. Only parallel combinations (side-by-side) for the fan arrangements are considered subsequently since it was found that the series combination of the fans (back-to-back placement of the fans) is not efficient for increasing the volume of the air entering the stairwells [13]. Also, it was observed that two parallel fans at the first floor (i.e., ground floor) create better positive pressure zone inside the stairwell to effectively drive away the combustion products than placing them in the floors other than the first. ...
... Similar analogies can be made for other relevant cases (Case 3, 7, 9, 13, and 15). When a stairwell that is farther from fire location is chosen as the attack stairwell, the pressure zone is not able to drive away combustion products as it has to pressurize long hallway (see Cases 5,6,13,14,15,and 16). ...
This study addresses the selection of the pressurization stairwell and the ventilation stairwell for fighting fires in a high-rise structure with multiple stairwells. The specific case of three stairwells, where one is regular and the other are paired scissor stairwells, has been considered in this study and various scenarios have been analyzed. Through simulations of a model that has been validated by on-site pressure tests, it is found that the most effective scenario which provides a safer environment for the rescue-operation is choosing the closest stairwell to the fire apartment as the pressurization stairwell, and the farthest stairwell to the fire apartment as the ventilation stairwell.
... Number of studies have been carried out to develop tactics that can improve the performance of PPV operations. These studies are mostly focused on the use of multiple PPV fans, their placement locations, and their respective positions [5][6][7][8][9]. ...
This technical note presents a strategy to increase the effectiveness of Positive Pressure Ventilation (PPV) tactics in firefighting. It is shown that deployment of a Door Open Area Reducer (DOAR) in an appropriate position, which increases the resistance to the air escaping the stairwell, can significantly improve effectiveness of PPV performance. The simulation results demonstrate that an optimal placement of the fan combined with an optimized DOAR height can increase the pressure significantly yielding higher PPV effectiveness.
... The series arrangement (back-to-back) has been found in-effective since the second fan was unable to significantly increase the volume of air actually entering the stairwell [9,33]. Therefore, for the fire on fifth floor apartment, options (b) and (c) are chosen to study effectiveness of the deployment of multiple PPV fans. ...
In high-rise buildings wind can greatly impact fires, creating extremely dangerous and life-threatening environments for both the firefighters and the building's occupants. Positive pressure ventilation (PPV) is found to be a successful tactic, not only to mitigate wind driven fires in high-rises, but also to significantly improve firefighters’ safety. The efficacy of PPV is strongly influenced by various parameters, mainly structural layouts, wind conditions, and fan deployment configurations. To optimize the application of PPV in high-rise fires, this paper investigates the impact of wind speed (0–10 m/s; 0–5 Beaufort wind scale) and relevant operational parameters on temperatures and smoke conditions using computational fluid dynamics model - the Fire Dynamics Simulator (FDS 5.0). The temperature results demonstrate that the effectiveness of PPV decreases with increasing wind speed necessitating the use of wind control devices (WCDs) in conjunction with deployment of PPV fans to mitigate the flow of heat and reduce the temperatures at primary vantage points (stairwell and public hallway). This tactic ultimately provides a safer environment for firefighters.
... Slutsatsen var här att användningen av övertrycksventilation i stora lokaler (större än normala lägenheter) kan medföra ökade risker och försämrade arbetsförhållanden för räddningstjänstens personal och därför bör undvikas (Svensson & Werling, 2001). Försök i en större skolbyggnad, vilken omfattade såväl ett korridorsystem som en större samlingsaula/idrottshall, visade att övertrycksventilation kunde medverka till förbättrade möjligheter för såväl utrymning som överlevnad och räddningsinsats (Kerber & Madrzykowski, 2008). Även om användningen av fläktar inte nödvändigtvis förbättrade förhållandena i brandrummet (samlingsaulan/idrottshallen), minimerades rök-och brandspridningen till övriga utrymmen (korridorer). ...
The purpose of this study was to make a brief overview of past and present research activities with regard to fire service response to fires in buildings and, to provide a number of proposals for future research activities. In addition to the research, the study highlights a number of trends and developments. The study makes a brief description of the general level of knowledge and available research in the areas of operational environment (buildings), fire behavior, fire ventilation, firefighting, methodology, protection, safety and health, and tactics. The conclusions of this study contain a number of suggestions for future research with a bearing on fire service response in case of fire in buildings. The main conclusion includes the need for an increase in making research available to the fire service community.
... A third conclusion was that an increase in exhaust area (multiple windows versus a single window) improves the PPV effectiveness. Kerber et al. [8] conclude from their study on PPV in large structures, that effective use of PPV is only applicable to a limited number of storeys. Indeed, the generated overpressure decreases with distance from the inlet opening, due to friction losses. ...
... Two important factors are the distance between the fan and the door and the inclination of the fan. Note that Kerber et al. [8] also presented results for a systematic study on PPV effectiveness, but their focus was on the creation of over-pressure, with particular attention for high-rise buildings. Our study at hand focuses on the flows generated, with measurements taken in low-rise and mid-rise buildings. ...
... The best known placements are "in series" (2 fans, one positioned behind the other) and "in parallel" (2 fans, one positioned beside the other). However, V-shape positioning is also mentioned in the literature [8]. In the Vshape, a virtual letter V is drawn by the air flow axes through the middle of the door (as sketched in Figure 5). ...
During fire service interventions, positive pressure ventilation (PPV) systems with mobile fans are often used to try and make (or keep) a staircase smoke free and to remove smoke from the fire rooms. The positioning (distance from the door opening) and inclination angle of the fan determine the effect of the PPV fans in the staircase. In the present paper results are discussed of an experimental study, performed at full-scale. Based on different sets of cold experiments, the impact is quantified of: the distance between the fan and the door; the inclination angle of a single fan; and the use of multiple fans. The closer the single fan is put to the door opening, the more effective the PPV becomes. Obviously, there is a trade-off with effectiveness of the fire service intervention, since the fan must not block the door opening. With respect to inclination, it is best to apply an inclination angle of 75° (i.e., an upward tilting of the fan axis by 15°, which is the maximum value tested) for ventilation at ground level with the fan tested. This ensures safety in the case of fire at ground level due to full coverage of the entry door opening, while only a relatively limited loss in PPV effectiveness is observed compared to a horizontal fan (in some cases, the PPV effectiveness is even higher with inclined fan). When the fire room is at a higher floor, an inclination angle of 90° (i.e. horizontal fan axis) can generate a higher average flow velocity, depending on the staircase configuration inside the building. If two fans are used, V-shape positioning is shown to be more effective than a set-up in series or in parallel. A V-shape with inner angle of 60° between the fan axes is more effective than an angle of 90°. If three fans are available, still higher average flow velocities are measured. Positioning two fans outside in V-shape and one fan inside at the bottom of the staircase is more effective than putting the three fans outside, On the other hand, the latter set-up may be required for firefighting tactics.
... This can be achieved by creating the high (termed as " positive " ) pressure zone in stairwell which mitigates the flow of smoke and heat into the stairwell . This positive pressure zone inside the stairwell is created by directing a significant amount of airflow into the stairwell by the deployment of specially designed fans at the entrance of stairwell (and / or other appropriate locations of the stairwell)345. The pressure created by PPV fans must be greater than that of created by spread of fire so that PPV fan deployment can drive away the flow of smoke, heat and other combustion products. ...
... The pressure created by PPV fans must be greater than that of created by spread of fire so that PPV fan deployment can drive away the flow of smoke, heat and other combustion products. There are number of parameters including wind conditions, fan deployment techniques, control of doors, location of fire seed etc that influence the performance of PPV [2,4,5]. The results of the study described in this paper will provide an understanding of wind-driven high-rise fires, and offer guidelines for controlling the parameters that influence the performance of PPV operations. ...
... When one PPV fan is deployed at first floor, the positive pressure achieved by PPV operation is higher on the lower floors and it diminishes on the higher floors [4, 5]. This behavior can also greatly impact the performance of PPV on fires. ...
Positive Pressure Ventilation (PPV) is a firefighting tactic that can mitigate the spread of fire and the combustion products to improve the safety of firefighters and civilians in wind-driven high-rise fires than without PPV. The performance of a PPV tactic in wind-driven high-rise fires depends on various parameters that include wind speed, control of stairwell doors, number of fans, fan positions and placements, fire location etc. This paper describes the influence of these parameters on the efficacy of PPV operation that was studied by simulating wind-driven high-rise fire scenarios using computational fluid dynamics softwares Fluent 12.0 and NIST’s Fire dynamic simulator (FDS 5.0). The results obtained from Fluent and FDS found to be in close agreement with each other and have been used to optimize the PPV operation for better performance.
... Briefly, PPV can be described as a process where one or more fans are positioned such that a high pressure zone is created in the path of the growing fire. At the same time a vent is allowed, so the effect of the fan is to cease the spread of fire and vent the heat and smoke out though the opening [2] [3] [4]. It is important that the pressure created by PPV fan deployment must be greater than that of the fire to achieve the objectives of PPV [2] [3]. ...
... It is important that the pressure created by PPV fan deployment must be greater than that of the fire to achieve the objectives of PPV [2] [3]. The pressure achieved by PPV operation and the air velocity inside the stairwell diminishes from lower to upper floors when one PPV fan is deployed at first floor [2] [4] [5]. Especially, in real-life structures, considering the size of stairwells or leakages around the stairwell doors, firefighters may struggle to achieve the desired pressure levels on the upper floors of the structure. ...
... Significant amount of research is being done to develop the tactics that can improve the performance of PPV operation. Most of these tactics include the use of multiple PPV fans and various ways to place or position the fans [4] [5]. ...
Positive Pressure Ventilation (PPV) is a firefighting tactic that can assist firefighters in venting of smoke and high temperature combustion products in a more efficient manner and make the fire-rescue /suppression operation safer than without PPV. The pressure created by PPV operation must be greater than that of created by spread of fire. In real-life structures such as high-rise buildings, considering the leakages and size of stairwells, it becomes difficult to achieve the desired pressure at upper floors using PPV operation. With the help from FDNY (Fire Department of New York), on-site tests and computer simulation techniques were performed to study the behavior of PPV tactic. A technique was developed that significantly increases the positive pressure level achieved by a typical PPV operation. The efficacy of this technique was tested by conducting on-site experiments and numerical simulation methods using computational fluid dynamics software - Fluent 12.0 and NIST’s Fire dynamic simulator (FDS 5.0). The results of on-site experiments and numerical simulation methods found to be in close agreement with each other and confirmed the efficacy of this technique in improving the performance of typical PPV operation. This paper describes the results obtained from these on-site tests and numerical simulation methods. As FDNY is in the phase of implementing this instrument to ease and improve the PPV deployment operation, numerical simulation methods have been used to optimize this technique and the analysis discussed in this study also simplifies the PPV fan deployment operation for firefighters.
