NISTIR 7213 

Effect of Positive Pressure Ventilation on a Room Fire 

 Stephen Kerber 

William D. Walton 

U.S. Department of Commerce 

Technology Administration 

Building and Fire Research Laboratory 

National Institute of Standards 

and Technology 

Gaithersburg, MD 20899 

Sponsored in part by 

Department of Homeland Security

Federal Emergency Management Agency

United States Fire Administration
 

NISTIR 7213 

Effect of Positive Pressure Ventilation on a Room Fire 

 Stephen Kerber 

William D. Walton 

U.S. Department of Commerce 

Technology Administration 

Building and Fire Research Laboratory 

National Institute of Standards 

and Technology 

Gaithersburg, MD 20899 

March 2005 

Department of Homeland Security 

Tom Ridge, Secretary 

Federal Emergency Management Agency 

Michael D. Brown, Under Secretary of Emergency 

Preparedness and Response 

United States Fire Administration 

R. David Paulison, Administrator 

U.S. Department of Commerce

Carlos M. Gutierrez, Secretary

Technology Administration

Phillip J. Bond, Under Secretary for Technology

National Institute of Standards and Technology

Hratch Semerjian, Jr., Acting Director
1

 Effect of Positive Pressure Ventilation on a Room Fire 

Steve Kerber 

William D. Walton 

Abstract 

Fire departments may use ventilation blowers or fans to pressurize a structure prior to 

suppressing a fire. This pressurization or positive pressure ventilation (PPV) tactic can 

assist in the venting of smoke and high temperature combustion products and make 

attacking the fire easier than without PPV. However, this tactic also provides additional 

oxygen to the fire and can increase the rate of heat and energy being released. PPV has 

not been characterized carefully enough to establish specific guidelines for optimum use. 

This study examined gas temperatures, gas velocities and total heat release rate in a series 

of fires in a furnished room. The use of the PPV fan created slightly lower gas 

temperatures in the fire room and significantly lower gas temperatures in the adjacent 

corridor. The gas velocities at the window plane were much higher in the PPV case than 

in the naturally ventilated scenario. This higher velocity improved visibility 

significantly. PPV caused an increase in heat release rate for 200 seconds following 

initiation of ventilation but the heat release rate then declined at a faster rate than that of 

the naturally ventilated experiment. 

Disclaimer 

Certain trade names and company products are mentioned in the text or identified in an 

illustration in order to specify adequately the experimental procedure and equipment 

used. In no case does such identification imply recommendation or endorsement by the 

National Institute of Standards and Technology, nor does it imply that the products are 

necessarily the best available for the purpose. 
2

Table of Contents 

Abstract............................................................................................................................. 1 

Table of Contents .............................................................................................................. 2 

List of Tables ..................................................................................................................... 3 

List of Figures.................................................................................................................... 3 

1.0 Introduction................................................................................................... 5 

2.0 Overview of Experimental Series ................................................................ 6 

2.1 Instrumentation ................................................................................................... 7 

2.2 Fuel Load ............................................................................................................ 7 

 2.3 Experimental Procedure...................................................................................... 8 

3.0 Results ............................................................................................................ 8 

3.1 Heat Release Rate ............................................................................................... 9 

3.2 Room Gas Temperature .................................................................................... 10 

3.3 Doorway Gas Temperature............................................................................... 10 

3.4 Window Gas Temperature ................................................................................ 11 

3.5 Corridor Gas Temperature ................................................................................ 11 

3.6 Room Differential Pressure............................................................................... 11 

3.7 Window Gas Velocity....................................................................................... 12 

3.8 Doorway Gas Velocity...................................................................................... 12 

3.9 Uncertainty........................................................................................................ 13 

4.0 Discussion..................................................................................................... 14 

5.0 Conclusion ................................................................................................... 15 

6.0 Acknowledgements ..................................................................................... 16 

7.0 References.................................................................................................... 16
3

List of Tables 

Table 1 - Fire Load Weights ............................................................................................. 18 

Table 2 - Experimental Procedure .................................................................................... 18 

Table 3 - Observations...................................................................................................... 19 

Table 4 - Estimated Uncertainty in Experimental Data.................................................... 20 

List of Figures 

Figure 1 - Two Common PPV Fans.................................................................................. 21 

Figure 2 - PPV Cone of Air [5]......................................................................................... 21 

Figure 3 – Experimental Floor Plan.................................................................................. 22 

Figure 4 – External view of window in closed position ................................................... 23 

Figure 5 – External view of open corridor doorway......................................................... 24 

Figure 6 - Furniture Floor Plan ......................................................................................... 25 

Figure 7 - Instrumentation Floor Plan............................................................................... 26 

Figure 8 - Doorway and Window Probe and Thermocouple Locations ........................... 27 

Figure 9 – View of Doorway from inside the room into Corridor and Window, with 

Instrumentation ......................................................................................................... 27 

Figure 10 - Bidirectional Probe and Thermocouple Combination.................................... 28 

Figure 11 - Water Cooled Camera.................................................................................... 28 

Figure 12 - Book Case ...................................................................................................... 29 

Figure 13 - Book Case Dimensions .................................................................................. 29 

Figure 14 - Desk and Monitor........................................................................................... 30 

Figure 15 - Desk Dimensions ........................................................................................... 30 

Figure 16 - Monitor........................................................................................................... 31 

Figure 17 - Monitor Dimensions ...................................................................................... 31 

Figure 18 - Chair............................................................................................................... 32 

Figure 19 - Chair Dimensions........................................................................................... 32 

Figure 20 – Bunk Bed....................................................................................................... 33 

Figure 21 – Bunk Bed Dimensions................................................................................... 33 

Figure 22 - Ignition Setup................................................................................................. 34 

Figure 23 - Electrically Activated Matchbook Locations................................................. 34 

Figure 24 – Exterior View of Doorway to Corridor After the Start of Forced Ventilation 

(470 s) ....................................................................................................................... 35 

Figure 25 – Exterior View of Window After the Start of Forced Ventilation (380 s)...... 35 

Figure 26 – Doorway During Natural Ventilation Experiment (645 s)............................ 36 

Figure 27 - Window During Natural Ventilation Experiment (470 s).............................. 36 

Figure 28 - Heat Release Rate .......................................................................................... 37 

Figure 29 - Heat Release Rate Detail for 200 s Following Peak Output .......................... 38 

Figure 30 – Total Heat Released....................................................................................... 39 

Figure 31 - PPV Room Temperatures, Distances Measured From Ceiling...................... 40 

Figure 32 - Natural Ventilation Room Temperatures....................................................... 41 

Figure 33 - PPV Doorway Temperatures.......................................................................... 42 
4

Figure 34 - Natural Ventilation Doorway Temperatures.................................................. 43 

Figure 35 - PPV Window Temperatures........................................................................... 44 

Figure 36 - Natural Ventilation Window Temperatures................................................... 45 

Figure 37 - PPV Corridor Temperatures........................................................................... 46 

Figure 38 - Natural Ventilation Corridor Temperatures................................................... 47 

Figure 39 - PPV Room Differential Pressure ................................................................... 48 

Figure 40 - Natural Ventilation Room Differential Pressure............................................ 49 

Figure 41 - PPV Window Velocities ................................................................................ 50 

Figure 42 - Natural Ventilation Window Velocities......................................................... 51 

Figure 43 - PPV Room Doorway Velocity....................................................................... 52 

Figure 44 - Natural Ventilation Room Doorway Velocity ............................................... 53 
5

1.0 Introduction 

In the past positive pressure ventilation (PPV) often has been used by fire departments to 

ventilate a structure after a fire has been extinguished. Typically this allows fire fighters 

to complete salvage and overhaul operations in a less hazardous atmosphere. PPV is also 

being implemented as a tactic during a fire attack. The fan is started in coordination with 

a ventilation opening during the initial phase of fire attack. This tactic is designed to 

increase visibility and force heat away from the attack team as they locate and extinguish 

the fire. PPV has been implemented with some success but also with some difficulty. 

Positive pressure ventilation has not been carefully characterized in terms of gas 

temperatures, gas velocities and mass burning rates. Without additional understanding of 

the impacts or effects caused by PPV, the difficulties associated with PPV have given rise 

to several issues. When should PPV be used, and just as important, when should it not be 

used? What is the best location for the fan and where should the exhaust or vent opening 

be made? Does PPV provide oxygen to the fire and allow for quicker fire growth? What 

is the consequence if fire fighters or building occupants are between the fire and the 

exhaust opening? Are there certain types of construction that PPV cannot be used on? 

These are just a few questions that the fire service has developed based on their 

experience with PPV. 

As early as 1989, questions were posed in fire department training publications as to 

whether the positive pressure ventilation fans would intensify the fire by introducing 

additional oxygen. Carlson [1] responds to this question, stating that it is a possibility, 

but has no evidence or research to substantiate his answer. As part of their “Roundtable” 

discussion in 1999, Fire Engineering Magazine polled chiefs from around the country to 

determine if their departments used PPV and to what extent. Many of the polled 

departments used PPV, but some did not use it offensively with the explanation that the 

fire intensifying was a concern and this phenomena was not well understood [2]. This 

study provides experimental data to assist in quantifying the effects that the offensive use 

of PPV has on a well developed room fire. 

In 2001, Mark Yates conducted an investigation and survey of the usage of PPV in the 

Tyne and Wear Metropolitan Fire Brigade in the United Kingdom, Salt Lake City Fire 

Department in the United States, and the Aachen Fire Department in Germany [3]. The 

survey suggested a few reasons for the lack of implementation of PPV. Two of these 

reasons were the potential for increased damage to structures and insufficient research 

data and evidence available to support PPV’s benefits. This is further evidence that PPV 

lacks the firm scientific foundation necessary for optimum use for both salvage and 

overhaul as well as fire suppression operations. 

This research used a pair of full-scale experiments to examine how positive pressure 

ventilation affects the fire environment of a furnished room fire. This work provides a 

better understanding of the effective use of ventilation and leads to the development of 

guidelines for the most effective use of positive pressure ventilation. This work is a 

continuation of previous experiments that examined the flow created by PPV fans and 

NIST’s Fire Dynamic Simulator’s ability to model the results [4]. 
6

PPV fans are commonly powered with electric or gasoline engines and range in diameter 

from 0.30 m to 0.91 m (12 in to 36 in) (figure 1). Typically, a positive pressure 

ventilation fan is placed about 1.8 m to 3.0 m (6 ft to 10 ft) outside the doorway of the 

structure. It is positioned so that the “cone of air” produced by the fan extends beyond 

the boundaries of the opening (figure 2). With the doorway within the fan discharge, air 

pressure inside the structure increases. An exhaust opening in the structure, such as an 

opening in the roof or an open window, allows the air to escape due to the difference 

between the inside and outside air pressure. The smoke, heat and other combustion 

products are pushed out of the structure and replaced with ambient air [5]. 

2.0 Overview of Experimental Series 

 

A pair of full-scale experiments was performed at NIST’s Building and Fire Research 

Laboratory Large Fire Facility. The facility has interior dimensions, 36.6 m (120.0 ft) 

long, 18.3 m (60.0 ft) wide and 7.6 m (25.0 ft) high. A room was constructed within the 

facility under a 6 m x 6 m (20 ft x 20 ft) hood which was instrumented to allow for 

oxygen depletion calorimetry to measure the heat release rate produced by the fire in the 

room. The room had interior dimensions of 3.66 m x 4.27 m (12 ft x 14 ft) and a ceiling 

height of 2.44 m (8 ft) (figure 3). A window was located in the center of the 4.27 m wall 

(figure 4) and a doorway was located on the center of the 3.66 m wall. The doorway 

opened to a 1.22 m wide x 2.29 m long (4 ft x 7.5 ft) corridor (figure 5). Another 

doorway was located at the end of the corridor that was the same size as the doorway to 

the room. Both doorways were 2.06 m (6.75 ft) tall and 0.91 m (3 ft) wide. The window 

was 1.2 m (3.9 ft) tall and 0.89 m (2.9 ft) wide and 0.81 m (2.7 ft) above the floor to the 

sill (figure 3). A 6.1 m (20 ft) wall was constructed between the corridor doorway and 

room window to the exterior of the room in order to isolate the effects of the fan and not 

allow recirculation of smoke from the window back through the doorway. All of the 

walls and the ceiling were framed with 0.038 m x 0.089 m (1.5 in x 3.5 in) pine studs and 

sheathed with two layers of 0.01 m (0.375 in) gypsum board. The room was furnished 

with a bunk bed, stuffed chair, book case and desk (figure 6). The floor was covered with 

carpet and a computer monitor was placed on the desk. 

Two experiments were conducted with nearly identical fuel loads, examining the effect of 

the PPV fan on the room fire. The first experiment utilized a fan to forcibly ventilate the 

room just after the window was opened. The second experiment was similar to the first 

experiment except that it was naturally ventilated. The fan used was a 0.75 m (18 in), 

variable speed, electric positive pressure ventilator. The fan has a depth of 0.48 m, 

(18.75 in), width of 0.62 m (24.5 in) and height of 0.62 m (24.5 in). It has a maximum 

speed of 2200 RPM, a power rating of 746 W (1 hp) and a volumetric flow rating of 

6.64 m3

/s (14,060 ft3/min) [6]. The fan was positioned 2.44 m (8 ft) from the open 

doorway to the corridor at an angle of approximately 15 degrees from horizontal to create 

the cone of air around the doorway. 
7

2.1 Instrumentation 

Temperature measurements were made with 0.5 mm (0.02 in) nominal diameter type K 

bare bead thermocouples. A vertical thermocouple array was located in the center of the 

fire room with measurement locations of 0.025 m, 0.30 m, 0.61 m, 0.91 m, 1.22 m, 

1.52 m, 1.83 m and 2.13 m (1 in, 1 ft, 2 ft, 3 ft, 4 ft, 5 ft, 6 ft and 7 ft) below the ceiling. 

The corridor doorway also had a vertical array with measurement locations of 0.025 m, 

0.30 m, 0.61 m, 0.91 m, 1.22 m, 1.52 m, 1.83 m (1 in, 1 ft, 2 ft, 3 ft, 4 ft, 5 ft and 6 ft) 

below the top of the doorway opening. Three thermocouples were located in the room 

doorway, 0.30 m (1 ft) from the top of the doorway, 0.30 m (1 ft) from the bottom of the 

doorway and the midpoint of the doorway at 1.02 m (figure 7). Six additional 

thermocouples were placed in the ventilation window. Three where located 0.30 m (1 ft) 

in from each side of the window at heights of 0.15 m, 0.61 m and 1.07 m (0.5 ft, 2 ft and 

3.5 ft) from the bottom of the window (figures 8, 9). 

Gas velocity measurements were recorded in the window and in the fire room doorway 

using bi-directional probes (figure 10). The doorway had measurement locations of 

0.30 m (1 ft) from the top of the doorway, 0.30 m (1 ft) from the bottom of the doorway 

and the midpoint of the doorway. The ventilation window had six bi-directional probes 

in the same locations as the thermocouple locations shown in figure 8. Probes were 

connected to Setra Systems Model 264 differential pressure transducers. Since both in 

and outflow was expected, each transducer had the capacity to monitor positive and 

negative pressure differentials. Bi-directional high ranges up to 62 Pa (0.009 PSI) were 

utilized because of the flow that was expected in the two openings. A set of pressure 

transducers was also positioned in the rear corner of the room adjacent to the bookcase to 

examine the differential pressure created at 0.30 m, 1.22 m, 2.13 m (1 ft, 4 ft and 7 ft) 

from the floor [7]. 

Video recordings were made of each experiment. Two cameras were positioned on the 

exterior of the room. One had the view of the ventilation window and the other the open 

doorway to the corridor. Two water cooled cameras were positioned inside the room 

(figure 11). One camera was placed just above the floor near the bunk beds viewing the 

gas flow between the window and doorway. The second interior camera was positioned 

near the floor viewing the ignition location and flame spread across the bunk beds. 

The combustion products were captured by a 6 m x 6 m (20 ft x 20 ft) hood which was 

instrumented for oxygen consumption calorimetry. Oxygen depletion readings were 

continuously monitored in order to calculate the total heat release rate of the fire 

room [8]. 

2.2 Fuel Load 

The fuel load was selected in order to represent a typical bedroom configuration. It was 

also intended to create a fuel rich atmosphere to make burning dependent on the available 

oxygen. Both experiments had similar furniture and a total fuel mass that was 250.6 kg 

and 251.6 kg for experiment 1 and 2, respectively (Table 1). The book case was made of 

0.013 m (0.5 in) thick compressed particle board covered with a plastic laminate top 
8

(figures 12, 13). The desk was also made of the compressed particle board with a 

laminate top, but was 0.038 m (1.5 in) thick (figures 14, 15). The 0.38 m (15 in) nominal 

size computer monitor on the desk had a plastic shell and a glass face (figures 16, 17). 

The chair located in the corner had a wood frame; polyurethane cushions and cotton 

cover (figures 18, 19). Finally, the bunk beds were framed out with 0.038 m x 0.089 m 

(1.5 in x 3.5 in) pine lumber (figures 20, 21). All of the mattresses were positioned on 

box springs and were covered with cotton bedding consisting of fitted sheets, blankets, 

comforters, pillows and pillow cases. The mattresses consisted of a polyester cover, twin 

innersprings and polyurethane foam. The carpet was polypropylene based and covered 

the floor wall to wall, but did not extend into the corridor. There was no padding under 

the carpet, but a 0.01 m (0.375 in) thick sheet of gypsum board was placed under the 

carpet. 

2.3 Experimental Procedure 

 

The fire was ignited using two electrically activated books of matches located in the 

mattress of the lower bunk, in the corner nearest the center of the room (figure 22). The 

electric matches consisted of a match book with the cover placed behind the matches, 

exposing the match heads. Nickel-Chromium wire was spiraled through the match heads 

and taped to the bottom corners of the match book. A copper wire was connected to each 

end of the nickel-chromium wire with alligator clips and run to the exterior of the room 

where they were connected to an igniter box. The igniter box sent current through the 

wire, heating the wire and, in turn, igniting the matches providing ignition. One of the 

match books was cut into the mattress and the second was placed under the bedding, 

directly on top of the mattress to ensure a strong ignition (figure 23). 

At the time of ignition, the window was closed and the fire’s only source of oxygen 

beyond the room was through the open room doorway which connected to the corridor 

via a doorway. The fire was allowed to grow until flashover conditions were reached and 

the fire became oxygen limited, as determined by the internal video. Once the fire was 

oxygen limited for a short period of time, the window was opened from the outside of the 

room to ventilate the fire. Both of the experiments were ventilated 345 s after ignition. 

In the positive pressure ventilation experiment, the window was opened and 5 s later the 

fan was turned on to full speed until 1380 s, when the fan was turned off to assess the 

structure and begin extinguishment. In the naturally ventilated experiment, the window 

and doorway provided ventilation until the fuel in the room burned to completion. Table 

2 provides the timeline of events. 

3.0 Results 

Cameras at four locations allowed for the visualization of most of the fire growth and the 

combustion gas flow out of the furnished room. Both experiments experienced very 

similar fire growth up until the time that the window was opened. In the PPV ventilated 

experiment, flashover occurred at 275 s and zero visibility at 278 s. In the natural 

ventilation experiment, flashover occurred at approximately 285 s and zero visibility at 

298 s. While the growth was very similar in both experiments, the visibility returned 
9

more rapidly in the PPV experiment. The view from the water cooled camera focused on 

the corner of the room with the bunk beds showed visibility began to return 181 s after 

the ventilation in the PPV experiment and 395 s after the ventilation of the naturally 

ventilated case. Clear visibility inside the room returned to the PPV ventilated 

experiment 120 s prior to that of the naturally ventilated experiment. 

In both experiments, a black smoke flow was observed in the corridor prior to 300 s and 

flames were not observed in the corridor doorway until the window was ventilated. 

Within 10 s of opening the window, flames extended out of the corridor doorway. The 

PPV fan forced all burning out of the corridor and back into the room by 516 s. Once the 

fan was activated, it took 130 s to completely reverse the flow back into the room. At 

that point, little or no smoke was seen coming out of the room doorway. Flames were 

observed in the corridor of the naturally ventilated experiment until 1200 s (figures 24, 

26). 

The exterior view of the window showed that it took less than 5 s for flames to come out 

of the window after ventilation in both experiments. The flames in the PPV ventilated 

experiment extended at least 1.83 m (6 ft) from the window. The flames from the 

naturally ventilated experiment extended approximately 0.91 m (3 ft) from the outside 

edge of the window (figures 25, 27). Detailed observations are tabulated in Table 3. 

3.1 Heat Release Rate 

The maximum heat release rate was 14 MW for the PPV ventilated fire and close to 

12 MW for the naturally ventilated fire. Peak heat release rates of both fires occurred 

approximately 40 s after window ventilation with a spike to their respective maximum. 

The peak of the PPV experiment occurred 5 s after that of the natural experiment. This 

corresponded to the 5 s period before the PPV fan was started. Comparing the heat 

release rate between the time of peak and the time where the two curves intersect showed 

that the PPV created a higher burning rate by approximately 60 % for about 200 s after 

the fire reached its maximum output. After the heat release rate spike, the PPV output 

remained 4 MW above that of the naturally ventilated experiment for 70 s. At the end of 

those 70 s, the rates converged until 590 s when the naturally ventilated fire had the 

higher heat release rate. The naturally ventilated fire remained roughly 1 MW above the 

output of the PPV ventilated fire until the end of the experiment (figures 28, 29). The 

integral of the heat release rate curve in figure 30 provided the total heat released over the 

duration of both experiments. The fan caused heat to be released quicker in the PPV 

experiment, but ultimately both experiments released approximately the same amount of 

heat. 

For fires burning in the open under the laboratory hood, the chemical power measured by 

the oxygen depletion calorimeter is equal to the heat release rate from the fire as a 

function of time. However, for a fire within a room, the effluent from the enclosure is a 

mixed average of the upper layer gases, and does not represent the instantaneous heat 

release rate of the fire. Prior to ventilation there was a delay in the heat release rate 

measured due to the room configuration. After the window was opened a majority of the 
10

burning took place on the exterior of the room which allowed for a faster more accurate 

measure of heat release rate. 

3.2 Room Gas Temperature 

The gas temperatures measured in the room were similar for both experiments prior to 

ventilation as each fire grew to an initial peak of approximately 800  ̊C (1470  ̊F). 

Flashover occurred approximately 270 seconds (s) after ignition and both fires became 

ventilation limited. Once the fires were ventilation limited, the upper layer temperatures 

decreased to 700  ̊C (1290  ̊F). When ventilation was started in the experiment with a 

PPV fan, the upper layer room - gas temperature increased temporarily to 800  ̊C 

(1470  ̊F), quickly dropped to 550  ̊C (1020  ̊F) and then rapidly increased to the 

maximum temperature of approximately 980  ̊C (1800  ̊F). The maximum temperature 

was maintained for a short period of time and then the temperatures in the room steadily 

decreased to 400  ̊C (750  ̊F) at a rate of 0.8  ̊C /s. At 1200 s into the experiment a piece 

of the burning bunk bed falling onto the thermocouple leads causing an artificial room 

temperature increase. The room gas temperatures shown in figure 31 are inaccurate after 

this point. 

The naturally ventilated fire produced a much smoother time evolution of room 

temperatures. After ventilation, the temperatures rapidly increased to the maximum 

temperature of 1050  ̊C (1890  ̊F). The temperatures remained around 1000  ̊C (1830  ̊F) 

for approximately 300 s. Once the temperatures began to decrease the values did so 

steadily to 500  ̊C (932  ̊F) at a rate of 0.8  ̊C /s. At 1430 s there was a rapid decrease in 

temperature to 100  ̊C (210  ̊F) as the fuel in the room was nearly consumed (figure 32). 

3.3 Doorway Gas Temperature 

The temperatures recorded in the upper portion of the doorway to the room were similar 

to those within the room. For both experiments the temperatures at the top and middle of 

the doorway were around 600  ̊C (1110  ̊F) while the lower portion of the doorway 

remained less than 100  ̊C (210  ̊F) prior to window ventilation. This was consistent with 

the fire drawing a large volume of ambient air into the room at the lower section of the 

doorway. 

After positive pressure ventilation was started, the gas temperatures increased quickly to 

the peak temperatures of 1000  ̊C (1830  ̊F) at the top, 800  ̊C (1470  ̊F) in the center and 

550  ̊C (1020  ̊F) at the bottom of the doorway. Once the fan forced the air into the room, 

the doorway temperatures began to decline and continued to decrease until the end of the 

experiment (figure 33). A small increase in temperature occurred at approximately 

1380 s which was consistent with the turning off of the fan. The increase is further 

evidence of the cooling effects of the fan. 

The doorway temperatures for the naturally ventilated experiment were higher than those 

of the PPV experiment for a longer time period. It took approximately 300 s for the 

maximum temperatures to be reached at the top of the doorway. Both the top and center 

of the doorway reached a maximum of 1000  ̊C (1830  ̊F). The bottom of the doorway 
11

briefly peaked at 700  ̊C (1290  ̊F) before dropping to 200  ̊C (390  ̊F) as the fire 

continued to burn. Temperatures slowly declined to 100  ̊C (210  ̊F) over the 700 s after 

the peak (figure 34). 

3.4 Window Gas Temperature 

The gas temperatures monitored in the window were significantly different depending on 

the method of ventilation. The PPV experiment created more uniform gas temperatures 

in the window due to the unidirectional flow out of the window. Flames and hot gases 

could be observed coming out of the entire cross sectional area of the window. A 

bidirectional flow pattern existed in the naturally ventilated fire experiment. Flames 

could be seen in the entire window for a short period of time and then air entered the 

lower third of the window for the remainder of the experiment. The gas temperatures in 

the PPV experiment were all between 900  ̊C (1650  ̊F) and 1100  ̊C (2010  ̊F) while the 

naturally ventilated experiment had temperatures of 1000  ̊C (1832  ̊F) at the top and 

600  ̊C (1110  ̊F) at the bottom of the window. The PPV experiment required 200 s to 

reach these temperatures while the naturally ventilated experiment took approximately 

400 s (figures 35, 36). 

3.5 Corridor Gas Temperature 

The corridor doorway gas temperatures also showed a significant difference between the 

two ventilation tactics. Approximately 120 s after the fan was started; the fan was able to 

reverse the natural tendency for the gas to flow back into the room. This created a 

unidirectional flow. After ventilation started in the PPV experiment, the gas temperature 

reached nearly 700  ̊C (1290  ̊F) at the very top of the doorway. Once the fan was turned 

on, the upper doorway temperatures dropped and all of the other gas temperatures in the 

doorway never increased above 200  ̊C (390  ̊F). The bottom half of the doorway 

remained slightly above ambient temperatures of 25  ̊C (77  ̊F). The naturally ventilated 

gas temperatures were different due to the flow of combustion gases and flames that 

ventilated out of the corridor doorway. Gas temperatures in the upper third of the 

doorway were between 600  ̊C (1110  ̊F) and 900  ̊C (1650  ̊F) after ventilation (window 

opened). The mid doorway temperature rose as high as 400  ̊C (750  ̊F) while the 

bottom remained around 100  ̊C (210  ̊F). The temperature trends in the corridor were 

very similar to those of the room doorway (figures 37, 38). 

3.6 Room Differential Pressure 

Differential pressure readings were taken to examine the static pressure in the room 

created by the fire and the impact of the PPV fan on this pressure. The interior pressure 

readings were referenced to the pressure at the same elevation on the outside of the room. 

Before ignition in the PPV experiment, the fan created uniform pressures at all three 

elevations of 21 Pa (0.003 PSI). After ignition, the fire created pressures of 34 Pa 

(0.005 PSI) at the top probe, 14 Pa (0.002 PSI) at the middle probe and -14 Pa 

(-0.002 PSI) at the lower probe. Once the window was opened and the fan was turned on, 

these differential pressures became 62 Pa (0.009 PSI), 41 Pa (0.006 PSI) and 21 Pa 

(0.003 PSI) respectively. These pressures held constant for a period of time when the fire 
12

was at peak and then declined steadily. The naturally ventilated fire created differential 

pressures of 28 Pa (0.004 PSI) at the top probe, 7 Pa (0.001 PSI) at the middle probe and 

-14 Pa (-0.002 PSI) at the bottom probe. These differential pressures declined slightly 

until the fire diminished (figures 39, 40). 

3.7 Window Gas Velocity 

Before the PPV ventilated experiment, an ambient flow experiment (without a fire) of the 

fan through the room was conducted. The experiment produced an average velocity of 

5 m/s out of the window. For the PPV experiment, velocities on the order of 5 m/s to 

20 m/s were measured. The highest velocity occurred just after the window was opened 

and the fan was turned on. With the fire growing, the velocity increased to 20 m/s and 

slowly decreased to the fan velocity of 5 m/s as the fire decreased. The naturally 

ventilated experiment had a bidirectional flow through the window with the highest 

velocities of 12 m/s at the top of the window. The gas velocity in the middle of the 

window was about 7 m/s out of the room while the bottom of the window had flow into 

the room at 2 m/s. It took longer for the maximum velocities to be reached than in the 

PPV experiment but this was also directly proportional to the growth of the fire (figures 

41, 42). In the three minutes following the window being opened, the average gas 

velocity produced by the PPV experiment was 14 m/s while in the naturally ventilated 

experiment; the average gas velocity was 5.5 m/s. 

3.8 Doorway Gas Velocity 

The gas velocities into the room through the doorway were lower than those out through 

the window. The PPV fan alone created average flow velocities of 3 m/s to 4 m/s as 

shown in figure 38 for times of -2000 s to -1200 s. The negative time values represent 

times prior to ignition. Prior to ventilation, there was a 4 m/s to 6 m/s flow out of the top 

two-thirds of the doorway and a flow into the room in the bottom one-third of the 

doorway of 2 m/s. After the fan was activated the bottom two-thirds of the doorway 

flowed into the room and the flow in the upper third of the doorway fluctuated between in 

and out of the room. Eventually the fan was able to completely move air into the room 

over the entire doorway cross section. The naturally ventilated experiment began in the 

same manner as the PPV experiment with bidirectional flow through the doorway. Once 

ventilation was started, the gas velocities held rather steady until the fire began to 

decrease with the velocities decreasing as well. The flows into the room may be 

underestimated due to the orientation of the bi-directional probes. The probes were faced 

into the room and perpendicular to the corridor which may not have measured the full 

magnitude of the velocity into the room but were accurate for the flows out of the room 

(figures 43, 44). The flow out of the room had to pass in the direction of the centerline of 

the probes yielding a more accurate differential pressure as opposed to the flow into the 

room that may have passed the bi-directional probe at an angle to the centerline of the 

probe causing lower differential pressure readings, which correspond to under estimation 

of the gas velocities. 
13

3.9 Uncertainty 

There are different components of uncertainty in the gas temperatures, mass of fuel 

packages, gas velocity and heat release rate data reported here. Uncertainties are grouped 

into two categories according to the method used to estimate them. Type A uncertainties 

are those which are evaluated by statistical methods, and Type B are those which are 

evaluated by other means [9]. Type B analysis of systematic uncertainties involves 

estimating the upper (+ a) and lower (- a) limits for the quantity in question such that the 

probability that the value would be in the interval (± a) is essentially 100 %. After 

estimating uncertainties by either Type A or B analysis, the uncertainties are combined in 

quadrature to yield the combined standard uncertainty. Multiplying the combined 

standard uncertainty by a coverage factor of two results in the expanded uncertainty 

which corresponds to a 95 % confidence interval (2σ). 

Components of uncertainty are tabulated in Table 4. Some of these components, such as 

the zero and calibration elements, are derived from instrument specifications. Other 

components, such as radiative cooling/heating, include past experience with 

thermocouples in high temperature fuel rich environments. 

The uncertainty in the upper layer gas temperature measurements includes radiative 

cooling in each of the experimental series, but also includes radiative heating for 

thermocouple located in the lower layer of the full-scale experiments. Pitts et al. [10] 

quantified the errors of bare bead thermocouples as ranging from 7 % in the hot upper gas 

layer to as much as 75 % in the lower layer. The potential for large errors in the lower 

layer are a function of the effective temperature of the surroundings. In cases where the 

effective temperature of the surroundings is high, the error can be more significant. In 

cases, similar to a developing fire in a compartment, the temperature measurement errors 

in the lower layer are smaller as the fire develops through flashover, since the effective 

temperature of the floor and walls are relatively cool. Post-flashover, the potential for 

measurement error increases as the temperature of the surroundings increase. Small 

diameter thermocouples were used to limit the impact of radiative heating and cooling. 

This resulted in an estimate of ±15 % total expanded uncertainty in temperature. 

Differential pressure reading uncertainty components are derived from pressure 

transducer instrument specifications. The transducers were factory calibrated and the 

zero and span of each was checked in the laboratory prior to the experiments. The 

readings from the pressure transducers were used to generate gas velocities. 

Load cells were utilized to measure fuel package mass. The load cell was calibrated with 

a standard mass prior to recording the mass of each fuel item. After obtaining mass data 

on each of the fuel components, items were selected at random to be reweighed in order 

to estimate repeatability. 

Each length measurement was taken carefully. However due to some construction issues, 

such as the size and straightness of the lumber, the curves of the furniture, and the 

symmetry of the large room, the total expanded uncertainty for room dimensions was 

estimated to be 6 %. 
14

Total expanded uncertainties associated with oxygen calorimetry techniques is discussed 

in greater detail by Bryant et al. [8]. This uncertainty was estimated to be 11 % and 

included components derived from gas concentrations, temperature and gas flows. This 

estimation is based on the calorimetry system alone and does not account for the 

uncertainty that exists due to the experimental configuration. There is a delay time for 

the combustion gases to reach the hood and calorimetry instrumentation. The heat 

released within the fire room has an additional uncertainty associated with it. This 

uncertainty varies during the experiment. After the window was opened the uncertainty 

was minimized due to the majority of the burning occurred outside of the room. 

4.0 Discussion 

 

The impact of positive pressure ventilation on the gas temperature, window gas velocity, 

and mass burning rate has been investigated using different fuel packages and different 

room/structural configurations. Stott studied typical home furnishings in a single story 

structure. Svensson utilized fuel fires in three rooms of a larger structure. Ezekoye 

employed a polyurethane foam fuel in a 4 room residential structure. Different capacity 

PPV fans were utilized by each study. Instrumentation typically included upper and 

lower layer gas temperatures and one experimental series included pressure transducers 

for monitoring gas velocities. 

Stott [11] conducted a series of experiments in Preston, U.K. utilizing furnished rooms. 

These experiments were instrumented with thermocouples but relied upon subjective 

feedback from the participants that suppressed the fire or watched from outside. These 

experiments showed that there was a minor temperature elevation after the use of the fan, 

approximately 10  ̊C (18  ̊F). The experiments also demonstrated that there was no flame 

extension to the corridor, the temperature decreased and the visibility improved after the 

initiation of PPV. The report also stated that the fire growth rate was not greatly 

increased by the fan. The relatively small increase in burning rate as PPV was initiated is 

consistent with the data collected by this study for a single furnished room. 

Svensson [12] of the Swedish Rescue Services Agency also conducted an experimental 

study of ventilation during fire fighting operations. This experimental setup utilized three 

rooms on the first floor of a fire training facility. A 0.5 m diameter heptane pool fire was 

utilized which generated a heat release rate of 0.37 MW. This was a significantly smaller 

fire (in terms of heat release rate) than the fully furnished rooms in these experiments 

which released heat at a rate of 11 MW to 14 MW. The smaller heat release rate heptane 

pool fire generated much lower temperatures, 300  ̊C (570  ̊F), than was monitored in the 

furnished room, 800  ̊C (1470  ̊F). Svensson did report an increase of 40 % in the 

burning rate after PPV was initiated. This is comparable to the 60 % increase that was 

produced in the furnished room in this study. The furnished room had a greater fuel 

surface area which would have been consistent with the difference in the burning rate. 

Svensson also reported significantly lower pressure differentials. The larger room size 

may account for some of this difference but the main reason is likely the smaller fan 

output. The fan used in Svensson’s experiments was rated at approximately one third 

that of the one used in these experiments. This difference in fan size is also consistent 

with the smaller flows that were recorded in Svensson’s experiments. 
15

Another set of experiments was conducted in the United States by Ezekoye, Lan and 

Nicks [13] of the University of Texas at Austin. These experiments examined positive 

pressure attack for heat transport in a house fire. The fuel source chosen for those 

experiments was 9 kg (19.8 lb) of polyurethane foam, oriented on a rack, capable of 

generating a peak heat release rate per unit area of 1.2 MW/m2

. This fuel package 

produced temperatures of 760  ̊C (1400  ̊F) at the ceiling and 200  ̊C (390  ̊F) at the lower 

levels but did not appear to cause post flashover conditions that were present in the 

furnished room fire experiments. The fan flow rate was similar to the one used in the 

furnished room. The mixing which caused higher temperatures in the lower layer are seen 

in both sets of experiments. Those experiments only reported temperatures so pressure 

differential, burn rate and gas flow velocity could not be compared. 

5.0 Conclusion 

 

As compared to natural ventilation, positive pressure ventilation caused higher fire room 

temperatures, increased window gas flows and higher pressure differentials for this set of 

furnished room burns. After the peak heat release rate was reached in both experiments, 

the temperatures with PPV remained 200  ̊C (360  ̊F) to 400  ̊C (720  ̊F) below the 

temperatures with natural ventilation for 800 s. The doorway temperatures with PPV 

peaked 200 s before, but quickly dropped to 200  ̊C (390  ̊F) to 500  ̊C (930  ̊F) below the 

naturally ventilated temperatures for 900 s following the peak in the PPV experiment. 

The window gas temperatures generated during the PPV experiment peaked 200 s before 

gas temperatures at the same location in the naturally ventilated experiment. In the 

naturally ventilated experiment, gas temperatures in the top two thirds of the window 

were higher than the PPV experiment, but gas temperatures in the bottom third were 

lower due to the inflow of air. Once the fan was running, the PPV corridor temperatures 

were as much as 500  ̊C (930  ̊F) less than comparable temperatures in the naturally 

ventilated experiment. 

The PPV fan alone generated gas velocities of 5 m/s in the window while the naturally 

ventilated fire generated velocities of nearly 12 m/s. In the experiment with the PPV fan, 

window gas velocities of nearly 20 m/s were generated, approximately equal to the 

additive velocities from the fan and the naturally ventilated fire. The fan quickly forced a 

unidirectional flow out of the window but took a period of time to completely reverse the 

flow out of the doorway and create a flow into the room. The fan was able to create a 

more tenable atmosphere as soon as it was turned on by reversing the natural flow out of 

the corridor, where the fire fighters would be approaching the fire for extinguishment. 

The heat release rate of the fire was increased by the fan for the 200 s following the peak 

heat release rate. This is critical because this is the time window in which the fire 

department would typically be advancing to extinguish the fire. The peak heat release 

rate for the two experiments occurred at approximately the same time and the rate with 

the PPV fan was 2 MW higher. The PPV fan caused a 60 % increase in burning rate 

during this time of initial fire department attack. This reinforces the importance of 

selecting a ventilation location close to the seat of the fire that allows for all of the 

combustion products to be ventilated to the exterior of the structure. The PPV ventilated 
16

experiment forced the flames at least 1.83 m (6 ft) out of the room as compared to the 

0.91 m (3 ft) by the naturally ventilated experiment. Flame extension out of the building 

openings may pose a potential ignition hazard to materials nearby. 

While the use of PPV in this particular configuration caused an increase in the room’s 

fire burning rate, it lowered the temperatures in the room, forced all of the combustion 

products to flow out of the room without affecting the corridor and improved the 

visibility leading up to and in the room itself. In this experimental configuration a fire 

fighting team would likely have been able to attack the PPV ventilated fire more easily 

than the naturally ventilated fire. 

This limited data set indicates that coordination of fire fighting crews is essential to carry 

out positive pressure ventilation in the attack stages of a fire. In this experiment, ideal 

coordination was simulated as the window was ventilated in the correct location and the 

fan was initiated s later. Once the fan was turned on, it took approximately 60 s to 90 s 

for the fire to reach its peak burning rate and the flow was forced away from the entrance. 

After this transition, the fire remained at a steady burning rate until the fuel was 

consumed. This would indicate that for the conditions in this experiment fire fighters 

should delay 60 s to 120 s after ventilation and fan start before advancing towards the 

fire. This would allow the flows to stabilize, temperatures to decrease and visibility to 

improve. The burning rate of the fire could become steady at the rate determined by the 

modified air flow and would be less likely to rapidly change as the fire fighters approach. 

The time to reach this new steady condition could vary with building layout, fire size and 

fan capacity. 

6.0 Acknowledgements 

 

The authors would like to thank Roy McLane, Andrew Milliken, Jessica Naff, Laurean 

DeLauter, Ed Hnetkovsky, Jack Lee, Robert Anleitner, Jay McElroy and Alexander 

Maranghides of the Building and Fire Research Laboratory at NIST for the support they 

provided during this set of experiments. In addition, the authors express gratitude to the 

United States Fire Administration, part of the Department of Homeland Security, and 

Robert McCarthy for their sponsorship and support of this important research program. 

7.0 References 

 

1. Carlson, G. Volunteer’s Corner, Positive Pressure Ventilation, Some Questions. Fire 

Engineering, March 1989 p. 9. 

2. Coleman, John. Roundtable, Positive Pressure Ventilation. Fire Engineering, 

August 1999 p. 22-32. 

3. Yates, Mark. Positive Pressure Ventilation - The Wind of Change. BCC. United 

Kingdom. 2001. 
17

4. Kerber, S and Walton, W. D. “Characterizing Positive Pressure Ventilation Using 

Computational Fluid Dynamics.” National Institute of Standards and 

Technology, NISTIR 7065, 2003. 

5. Tempest Technology Corporation, http://www.tempest-edge.com, January 2003. 

6. Super Vacuum Manufacturing Company, Inc., http://www.supervac.com, January 

2003. 

7. Setra Systems, Inc., Installation Guide, Setra Systems Model 264 Differential 

Pressure Transducer. Boxborough, MA., 1999. 

8. Bryant, R.A., Ohlemiller, T.J., Johnsson, E.L., Hamins, A.H., Grove, B.S., Guthrie, 

W.F., Maranghides, A., and Mulholland, G.W., The NIST 3 MW Quantitative Heat 

Release Rate Facility, NIST Special Publication 1007, National Institute of Standards 

and Technology, Gaithersburg, MD, 2003. 

9. Taylor, B. N. and C. E. Kuyatt, Guidelines For Evaluating and Expressing the 

Uncertainty of NIST Measurement Results. National Institute of Standards and 

Technology (U.S.) NIST-TN 1297; September, 20 p. 1994. 

10. Pitts, W.M., E. Braun, R.D. Peacock, H.E. Milter, E.L. Johnsson, P.A. Reneke, and 

L.G. Blevins, “Temperature Uncertainties for Bare-Bead and Aspirated 

Thermocouple Measurements in Fire Environments,” Thermal Measurements: The 

Foundation of Fire Standards. American Society for Experimenting and materials 

(ASTM), Proceedings. ASTM STP 1427, December 3, 2001, Dallas, TX. 

11. Stott, Richard. Report on PPV Trials at Oxford Road, Preston, U.K. 10-14 January, 

2000. 

12. Svensson, Stefan. “Experimental Study of Fire Ventilation During Fire Fighting 

Operations” , Fire Technology, Vol. 37, 2001, p 69-85. 

13. Ezekoye, O., Lan, C., Nicks, R. Positive Pressure Attack for Heat Transport in a 

House Fire. The 6th ASME-JSME Thermal Engineering Joint Conference. March 

16-20, 2003. 

14. Hall, Richard, Adams, Barbara, Essentials of Fire Fighting, 4th ed., Oklahoma 

State University, Stillwater, OK, 1998. 

15. “PPA Training, Positive Pressure Attack.” Tempest Training Systems, Fresno, 

CA 2002. 

16. Omega Engineering Inc., The Temperature Handbook, Vol. MM, pages Z-39-40, 

Stamford, CT., 2004. 
18

Table 1 - Fire Load Weights 

Item 

 

 

Mass (PPV Experiment) 

(kg) 

 

Mass (Natural Experiment) 

(kg) 

 

Bunk Bed Frame 19.15 20.13 

Top Mattress 14.60 17.14 

Top Box Spring 12.63 13.06 

Bottom Mattress 14.98 14.44 

Bottom Box Spring 14.21 12.94 

Pillows 0.57 0.56 

 0.58 0.56 

Pillow Cases 0.11 0.10 

 0.11 0.10 

Fitted Sheets 0.40 0.34 

 0.39 0.37 

Blankets 1.15 1.19 

 1.18 1.22 

Comforters 1.54 1.55 

 1.59 1.56 

Chair 27.13 27.80 

Book Case 27.08 26.17 

Desk 55.48 55.48 

Computer Monitor 17.09 17.90 

Carpet 40.66 39.00 

 

Total Weight 250.63 251.61 

Table 2 - Experimental Procedure 

Time (s) Natural Ventilation Positive Pressure Ventilation 

0 Ignition Ignition 

345 Window Open Window Open 

350 - PPV Fan On 

* Fire burned until all fuel was exhausted 
19

Table 3 - Observations 

PPV 

Ventilated 

Experiment 

Time (s) 

Natural 

Ventilation 

Experiment 

Time (s) 

Observation 

0 0 Ignition 

86 120 Flames touch top bunk box spring 

105 120 Black smoke out of corridor 

156 180 Flames extend to top bunk 

190 220 Top bunk fully involved in flames 

190 225 Smoke layer drops to bottom of window 

210 240 Bunk bed fully involved in flames 

275 285 Flashover 

278 298 Zero visibility 

270 300 Smoke down to 0.30 m (1 ft) above corridor floor 

345 345 Window Open 

350 350 Flames out of window 

420 460 Flames on corridor floor 

- 650 Reduction in smoke out of corridor, increase in flames 

480 - Little - no smoke out of corridor 

526 740 Limited visibility returned 

645 765 Room clear, everything burning 

- 900 Flames out of room but not out of corridor 

NA 960 Flames no longer extend out of window 

1200 - Bunk bed falls against thermocouple tree 

1230 1230 Burnout 

1380 - Fan is turned off 

Note: Times were estimated from the four video camera views 
20

Table 4 - Estimated Uncertainty in Experimental Data 

Component 

Standard 

Uncertainty 

Combined 

Standard 

Uncertainty 

Total 

Expanded 

Uncertainty 

Gas Temperature 

 Calibration[16] 

 Radiative Cooling 

 Radiative Heating 

 Repeatability 1

 Random 1

± 1 % 

- 5 % to + 0 % 

- 0 % to + 5 % 

± 5 % 

± 3 % 

- 8 % to + 8 % - 15 % to + 15 % 

Differential Pressure 

 Calibration[7] 

 Accuracy[7] 

 Repeatability 1

 Random 1

± 2 % 

± 1 % 

± 5 % 

± 5 % 

- 8 % to + 8 % - 15 % to + 15 % 

Mass of Fuel Package 

 Zero 

 Calibration 

 Repeatability1

 Random1

± 0.02 % 

± 1 % 

± 5 % 

± 3 % 

± 6 % ± 12 % 

Length Measurements 

 Instrumentation 

 Locations 

 Furniture Dimensions 

 Fan Location 

 Room Dimensions 

 Repeatability1

 Random1

± 1 % 

± 1 % 

± 1 % 

± 1 % 

± 2 % 

± 2 % 

± 3 % ± 6 % 

Notes: 1. Random and repeatability evaluated as Type A, other components as Type B. 
21

Figure 1 - Two Common PPV Fans 

 

Figure 2 - PPV Cone of Air [5] 
22

Figure 3 – Experimental Floor Plan 

4.27 m

3.66 m

1.68 m

1.37 m 1.37 m

1.68 m

1.22 m

0.15 m

0.15 m

2.29 m

2.03 m to Top of Doorway

CEILING HEIGHT = 2.44 m

2.03 m to Top of Doorway

2.03 m to Top

0.81 m to Sill

Separation Wall
23

Figure 4 – External view of window in closed position 
24

Figure 5 – External view of open corridor doorway 
25

4.27 m

3.66 m

0.16 m

0.22 m

0.3 m

Bunk Bed

Chair

Desk

Book Case

0.39 m

Figure 6 - Furniture Floor Plan 
26

4.27 m

3.66 m

1.83 m

2.13 m

0.46 m

0.3 m

TC/BDP

TC/BDP

TC/BDP

TC

TC

0.46 m

1.42 m

CAMERA

1.12 m

CAMERA

0.3 m

Figure 7 - Instrumentation Floor Plan 
27

0.91 m

1.02 m

0.3 m

0.46 m

0.15 m

0.61 m

1.22 m

0.3 m

0.89 m

0.3 m

2.03 m

0.15 m

0.3 m

 Figure 8 - Doorway and Window Probe and Thermocouple Locations 

 

Figure 9 – View of Doorway from inside the room into Corridor and Window, with 

Instrumentation 

TC/BDP 
28

 

 Figure 10 - Bidirectional Probe and Thermocouple Combination 

 Figure 11 - Water Cooled Camera 
29

 Figure 12 - Book Case 

1.82 m

0.91 m

0.91 m

0.31 m

 Figure 13 - Book Case Dimensions 
30

 Figure 14 - Desk and Monitor 

0.36 m

0.74 m

0.03 m

1.04 m

1.04 m

0.64 m

0.6 m

0.03 m

 Figure 15 - Desk Dimensions 
31

 Figure 16 - Monitor 

0.41 m

0.37 m

0.41 m

0.33 m

0.25 m

0.03 m

0.19 m

 Figure 17 - Monitor Dimensions 
32

 Figure 18 - Chair 

0.94 m

0.57 m

0.61 m

0.18 m

0.58 m 0.1 m

0.28 m

0.14 m

0.15 m

0.86 m

0.18 m

 Figure 19 - Chair Dimensions 
33

 Figure 20 – Bunk Bed 

1.89 m

2.06 m

0.31 m

1.07 m 0.99 m

1.73 m

1.32 m

0.71 m

0.2 m

0.2 m

0.09 m 0.04 m

 Figure 21 – Bunk Bed Dimensions 
34

Figure 22 - Ignition Setup 

Figure 23 - Electrically Activated Matchbook Locations 
35

 Figure 24 – Exterior View of Doorway to Corridor After the Start of Forced Ventilation (470 s) 

 Figure 25 – Exterior View of Window After the Start of Forced Ventilation (380 s) 
36

 Figure 26 – Doorway During Natural Ventilation Experiment (645 s) 

 Figure 27 - Window During Natural Ventilation Experiment (470 s) 
37

0

5000

10000

15000

0 500 1000 1500 2000

PPV

Natural

Heat Release Rate, kW

Time, s

Figure 28 - Heat Release Rate 
38

0

5000

10000

15000

400 440 480 520 560 600

PPV

Natural

Heat Release Rate, kW

Time, s

Figure 29 - Heat Release Rate Detail for 200 s Following Peak Output 
39

0

500000

1000000

1500000

2000000

2500000

3000000

3500000

4000000

0 500 1000 1500 2000

PPV

Natural

Total Heat Released, kJ

Time, s

Figure 30 – Total Heat Released 
40

Figure 31 - PPV Room Temperatures, Distances Measured From Ceiling. 

0

200

400

600

800

1000

1200

0 500 1000 1500 2000

0.025 m (1 in)

0.30 m (1 ft)

0.61 m (2 ft)

0.91 m (3 ft)

1.22 m (4 ft)

1.52 m (5 ft)

1.83 m (6 ft)

2.13 m (7 ft)

Gas Temperature, °C

Time, s

Window Open

Bed fell against 

thermocouple tree 
41

0

200

400

600

800

1000

1200

0 500 1000 1500 2000

0.025 m (1 in)

0.30 m (1 ft)

0.61 m (2 ft)

0.91 m (3 ft)

1.22 m (4 ft)

1.52 m (5 ft)

1.83 m (6 ft)

2.13 m (7 ft)

Gas Temperature, °C

Time, s

Window Open

Figure 32 - Natural Ventilation Room Temperatures 
42

0

200

400

600

800

1000

1200

0 500 1000 1500 2000

Top

Middle

Bottom

Gas Temperature, °C

Time, s

Window Open

Figure 33 - PPV Doorway Temperatures 

Fan Turned Off
43

0

200

400

600

800

1000

1200

0 500 1000 1500 2000

Top

Middle

Bottom

Gas Temperature, °C

Time, s

Window Open

Figure 34 - Natural Ventilation Doorway Temperatures 
44

0

200

400

600

800

1000

1200

0 500 1000 1500 2000

Top Left

Middle Left

Bottom Left

Top Right

Middle Right

Bottom Right

Gas Temperature, °C

Time, s

Window Open

Figure 35 - PPV Window Temperatures 

Fan Turned Off
45

0

200

400

600

800

1000

1200

0 500 1000 1500 2000

Top Left

Middle Left

Bottom Left

Top Right

Middle Right

Bottom Right

Gas Temperature, °C

Time, s

Window Open

Figure 36 - Natural Ventilation Window Temperatures 
46

0

200

400

600

800

1000

1200

0 500 1000 1500 2000

0.025 m (1 in)

0.30 m (1 ft)

0.61 m (2 ft)

0.91 m (3 ft)

1.22 m (4 ft)

1.52 m (5 ft)

1.83 m (6 ft)

2.13 m (7 ft)

Gas Temperature, °C

Time, s

Window Open

Figure 37 - PPV Corridor Temperatures 

Fan Turned Off
47

0

200

400

600

800

1000

1200

0 500 1000 1500 2000

0.025 m (1 in)

0.30 m (1 ft)

0.61 m (2 ft)

0.91 m (3 ft)

1.22 m (4 ft)

1.52 m (5 ft)

1.83 m (6 ft)

Gas Temperature, °C

Time, s

Window Open

Figure 38 - Natural Ventilation Corridor Temperatures 
48

-40

-20

0

20

40

60

80

-2400 -1600 -800 0 800 1600 2400

Top

Middle

Bottom

Pressure, Pa

Time, s

Window Open

Figure 39 - PPV Room Differential Pressure 

Fan Turned Off
49

-40

-20

0

20

40

60

80

-2400 -1600 -800 0 800 1600 2400

Top

Middle

Bottom

Pressure, Pa

Time, s

Window Open

Figure 40 - Natural Ventilation Room Differential Pressure 
50

-10

-5

0

5

10

15

20

25

-2400 -1600 -800 0 800 1600 2400

Top Left

Middle Left

Bottom Left

Top Right

Middle Right

Bottom Right

Gas Velocity, m/s

Time, s

Window Open

Figure 41 - PPV Window Velocities 
51

-10

-5

0

5

10

15

20

25

-2400 -1600 -800 0 800 1600 2400

Top Left

Middle Left

Bottom Left

Top Right

Middle Right

Bottom Right

Gas Velocity, m/s

Time, s

Window Open

Figure 42 - Natural Ventilation Window Velocities 
52

-10

-5

0

5

10

-2400 -1600 -800 0 800 1600 2400

Top

Middle

Bottom

Gas Velocity, m/s

Time, s

Window Open

Figure 43 - PPV Room Doorway Velocity 
53

-10

-5

0

5

10

-2400 -1600 -800 0 800 1600 2400

Top

Middle

Bottom

Gas Velocity, m/s

Time, s

Window Open

Figure 44 - Natural Ventilation Room Doorway Velocity