NISTIR 7137 

Simulation of the Dynamics of a Fire in the Basement of a 

Hardware Store – New York, June 17, 2001

 Nelson Bryner 

Stephen Kerber 
NISTIR 7137 

Simulation of the Dynamics of a Fire in the Basement of a 

Hardware Store – New York, June 17, 2001

Nelson Bryner 

Stephen Kerber

Building and Fire Research Laboratory 

National Institute of Standards and Technology 

Gaithersburg, MD 20899-8661

 May 2004 

U.S. Department of Commerce 

Donald D. Evans, Secretary 

Technology Administration 

Phillip J. Bond, Under Secretary for Technology 

National Institute of Standards and Technology 

Arden L. Bement, Director 
iii

Table of Contents 

 List of Figures........................................................................................iv 

 List of Tables........................................................................................vii 

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

2. Introduction......................................................................................................................... 2 

3. Fire Incident Summary ....................................................................................................... 3 

4. NIST Fire Dynamics Simulator (FDS) ............................................................................... 5 

4.1. Model Uncertainty ................................................................................................... 6 

5. Smokeview.......................................................................................................................... 6 

6. FDS Input............................................................................................................................ 9 

6.1. Geometry.................................................................................................................. 9 

6.2. Initial Fire and Fuel Package ................................................................................. 10 

6.3. Vents ...................................................................................................................... 14 

6.4. Openings Within the Structure............................................................................... 15 

6.5. Material Properties................................................................................................. 19

7. Model Results ................................................................................................................... 20 

7.1. Model Geometry and Iso-Surfaces Output ............................................................ 20 

7.2. Fire Simulation –Temperature and Oxygen Concentration Predictions................ 24 

7.3. Fire Door Activation.............................................................................................. 37 

8. Summary........................................................................................................................... 48 

9. Acknowledgements........................................................................................................... 48 

10. References......................................................................................................................... 48 
iv

List of Figures 

1. Plan View of Basement of Hardware Store.....................................................3 

2. Plan View of Hardware Store Basement with Exposures Defined by Fire 

 Department..........................................................................................4 

 3a. Basement of Hardware Store Plan View with Dimensions (feet) .........................11 

 3b. Basement of Hardware Store Plan View with Dimensions (meters) ......................11 

4. Merchandise and Shelving Not Included in Simulation ...................................12 

5. Near the Simulated Fire Source the Simulation Used Smaller Cells .....................12 

6. Remote From the Simulated Fire Source the Simulation Used Larger Cells.............13 

7. FDS Model Adjusts Walls to Fit Computational Grid and Cells .........................13 

8. Location of Paint, Solvents, and Propane in Basement of Hardware Store .............15 

9. View Generated by Model Simulation Looking from Front of Unit 20 Towards 

Rear Door .........................................................................................21 

10. Fire Positioned Just Inside Rear Door of Unit 20..............................................21 

11. Iso-Surface Plot for 500 kW fire at Time = 0 s ..................................................22 

12. Iso-Surface Plot for 500 kW fire at Time = 16 s ..............................................22 

13. Iso-Surface Plot for 500 kW fire at Time = 33 s ..............................................22 

14. Iso-Surface Plot for 500 kW fire at Time = 62 s ..............................................22 

15. Iso-Surface Plot for 500 kW fire at Time = 120 s.............................................22 

16. Iso-Surface Plot for 500 kW fire at Time = 300 s ............................................22 

17. Iso-Surface Plot for 500 kW fire at Time = 600 s.............................................23 

18. Iso-Surface Plot for 500 kW fire at Time = 1200 s............................................23 

19. Iso-Surface Plot for 500 kW fire at Time = 1311 s............... ..........................23 

20. Iso-Surface Plot for 500 kW fire at Time = 1324 s......................... .................23 

21. Iso-Surface Plot for 500 kW fire at Time = 1592 s.............................. ...........23 

22. Iso-Surface Plot for 500 kW fire at Time = 1629 s............................................23 

23. Temperature Profiles for 500 kW fire at Time = 118 s.......................................25 

24. Oxygen Concentrations for 500 kW fire at Time = 118 s....................................25 

25. Temperature Profiles for 500 kW fire at Time = 126 s.......................................25 

26. Oxygen Concentrations for 500 kW fire at Time = 126 s....................................25 

27. Temperature Profiles for 500 kW fire at Time = 236 s.......................................26 

28. Oxygen Concentrations for 500 kW fire at Time = 236 s....................................26 

29. Temperature Profiles for 500 kW fire at Time = 586 s.......................................26 

30. Oxygen Concentrations for 500 kW fire at Time = 586 s....................................26 

31. Temperature Profiles for 500 kW fire at Time = 1088 s......................................26 

32. Oxygen Concentrations for 500 kW fire at Time = 1088 s...................................26 

33. Temperature Profiles for 1000 kW fire at Time = 73 s.......................................28 

34. Oxygen Concentrations for 1000 kW fire at Time = 73 s....................................28 

35. Temperature Profiles for 1000 kW fire at Time = 81 s.......................................28 

36. Oxygen Concentrations for 1000 kW fire at Time = 81 s.....................................28 

37. Temperature Profiles for 1000 kW fire at Time = 126 s.....................................28 

38. Oxygen Concentrations for 1000 kW fire at Time = 126 s..................................28 
v

List of Figures cont’d. 

39. Temperature Profiles for 1000 kW fire at Time = 224 s.....................................29 

40. Oxygen Concentrations for 1000 kW fire at Time = 224 s..................................29 

41. Temperature Profiles for 1000 kW fire at Time = 428 s.....................................29 

42. Oxygen Concentrations for 1000 kW fire at Time = 428 s..................................29 

43. Temperature Profiles for 1000 kW fire at Time = 767 s.....................................29 

44. Oxygen Concentrations for 1000 kW fire at Time = 767 s..................................28 

45. Temperature Profiles for 2000 kW fire at Time = 53 s.......................................30 

46. Oxygen Concentrations for 2000 kW fire at Time = 53 s....................................30 

47. Temperature Profiles for 2000 kW fire at Time = 57 s.......................................30 

48. Oxygen Concentrations for 2000 kW fire at Time = 57 s....................................30 

49. Temperature Profiles for 2000 kW fire at Time = 90 s.......................................30 

50. Oxygen Concentrations for 2000 kW fire at Time = 90 s....................................30 

51. Temperature Profiles for 2000 kW fire at Time = 183 s.....................................31 

52. Oxygen Concentrations for 2000 kW fire at Time = 183 s..................................31 

53. Temperature Profiles for 2000 kW fire at Time = 375 s.....................................31 

54. Oxygen Concentrations for 2000 kW fire at Time = 375 s..................................31 

55. Temperature Profiles for 500 kW fire at Time = 120 s – Fire Door Open.................33 

56. Oxygen Concentrations for 500 kW fire at Time = 120 s – Fire Door Open..............33 

57. Temperature Profiles for 500 kW fire at Time = 128 s – Fire Door Open.................33 

58. Oxygen Concentrations for 500 kW fire at Time = 128 s – Fire Door Open..............33 

59. Temperature Profiles for 500 kW fire at Time = 235 s – Fire Door Open.................33 

60. Oxygen Concentrations for 500 kW fire at Time = 235 s – Fire Door Open..............33 

61. Temperature Profiles for 500 kW fire at Time = 566 s – Fire Door Open.................34 

62. Oxygen Concentrations for 500 kW fire at Time = 566 s – Fire Door Open..............34 

63. Temperature Profiles for 500 kW fire at Time = 1221 s – Fire Door Open...............34 

64. Oxygen Concentrations for 500 kW fire at Time = 1221 s – Fire Door Open............34 

65. Temperature Profiles for 1000 kW fire at Time = 74 s – Fire Door Open.................34 

66. Oxygen Concentrations for 1000 kW fire at Time = 74 s – Fire Door Open..............34 

67. Temperature Profiles for 1000 kW fire at Time = 82 s – Fire Door Open.................35 

68. Oxygen Concentrations for 1000 kW fire at Time = 82 s – Fire Door Open..............35 

69. Temperature Profiles for 1000 kW fire at Time = 128 s – Fire Door Open................35 

70. Oxygen Concentrations for 1000 kW fire at Time = 128 s – Fire Door Open............35 

71. Temperature Profiles for 1000 kW fire at Time = 223 s – Fire Door Open...............35 

72. Oxygen Concentrations for 1000 kW fire at Time = 223 s – Fire Door Open............35 

73. Temperature Profiles for 1000 kW fire at Time = 429 s – Fire Door Open...............36 

74. Oxygen Concentrations for 1000 kW fire at Time = 429 s – Fire Door Open............36 

75. Temperature Profiles for 1000 kW fire at Time = 788 s – Fire Door Open...............36 

76. Oxygen Concentrations for 1000 kW fire at Time = 788 s – Fire Door Open............36 

77. Temperature Profiles for 1000 kW fire at Time = 1270 s – Fire Door Open..............36 

78. Oxygen Concentrations for 1000 kW fire at Time = 1270 s – Fire Door Open...........36 

79. Temperature Profiles for 2000 kW fire at Time = 54 s – Fire Door Open.................38 

80. Oxygen Concentrations for 2000 kW fire at Time = 54 s – Fire Door Open..............38 
vi

List of Figures cont’d. 

81. Temperature Profiles for 2000 kW fire at Time = 58 s – Fire Door Open..................38 

82. Oxygen Concentrations for 2000 kW fire at Time = 58 s – Fire Door Open...............38 

83. Temperature Profiles for 2000 kW fire at Time = 87 s – Fire Door Open..................38 

84. Oxygen Concentrations for 2000 kW fire at Time = 87 s – Fire Door Open...............38 

85. Temperature Profiles for 2000 kW fire at Time = 166 s – Fire Door Open................39 

86. Oxygen Concentrations for 2000 kW fire at Time = 166 s – Fire Door Open.............39 

87. Temperature Profiles for 2000 kW fire at Time = 375 s – Fire Door Open................39 

88. Oxygen Concentrations for 2000 kW fire at Time = 375 s – Fire Door Open.............39 

89. Temperature Profiles for 2000 kW fire at Time = 644 s – Fire Door Open................39 

90. Oxygen Concentrations for 2000 kW fire at Time = 644 – Fire Door Open...............39 

91. Temperatures (Centigrade) versus Time for Combustion Gases Near the Fusible Link On 

the Fire Door for a 500 kW Fire..................................................................41 

92. Temperatures (Fahrenheit) versus Time for Combustion Gases Near the Fusible Link On 

the Fire Door for a 500 kW Fire..................................................................41 

93. Temperatures (Centigrade) versus Time for Combustion Gases Near the Fusible Link On 

the Fire Door for a 500 kW Fire – Fire Door Open............................................42 

94. Temperatures (Fahrenheit) versus Time for Combustion Gases Near the Fusible Link On 

the Fire Door for a 500 kW Fire – Fire Door Open................................................42 

95. Temperatures (Centigrade) versus Time for Combustion Gases Near the Fusible Link On 

the Fire Door for a 1000 kW Fire................................................................43 

96. Temperatures (Fahrenheit) versus Time for Combustion Gases Near the Fusible Link On 

the Fire Door for a 1000 kW Fire................................................................43 

97. Temperatures (Centigrade) versus Time for Combustion Gases Near the Fusible Link On 

the Fire Door for a 1000 kW Fire – Fire Door Open..........................................44 

98. Temperatures (Fahrenheit) versus Time for Combustion Gases Near the Fusible Link On 

the Fire Door for a 1000 kW Fire – Fire Door Open..........................................44 

99. Temperatures (Centigrade) versus Time for Combustion Gases Near the Fusible Link On 

the Fire Door for a 2000 kW Fire................................................................45 

100.Temperatures (Fahrenheit) versus Time for Combustion Gases Near the Fusible Link On 

 the Fire Door for a 2000 kW Fire...............................................................45 

101.Temperatures (Centigrade) versus Time for Combustion Gases Near the Fusible Link On 

 the Fire Door for a 2000 kW Fire – Fire Door Open.........................................46 

102.Temperatures (Fahrenheit) versus Time for Combustion Gases Near the Fusible Link On 

 the Fire Door for a 2000 kW Fire – Fire Door Open.........................................46 
vii

List of Tables

1. Approximate Timeline of Events for Front of Hardware Store..............................7 

2. Approximate Timeline of Events for Rear and Side of Hardware Store....................8 

3. Total Heat Release for a Number of Fuels.....................................................16 

4. Estimated Energy Content of Solvents in Basement of Hardware Store ..................17 

5. Estimated Heat Release Rate for Fraction of Solvent Consumed by Fire.................18 

6. Time of Ventilation Events for FDS Simulation .............................................19 

7. Thermal Properties Data.........................................................................20 
1

Simulation of the Dynamics of a Fire in the Basement of a 

Hardware Store – New York, June 17, 2001 

1. Abstract 

This report describes the results of computer model calculations to provide insight on the 

thermal conditions that may have occurred during a fire in a basement of a hardware store 

on June 17, 2001, in Queens, New York. These calculations were performed using the 

National Institute of Standards and Technology (NIST) Fire Dynamics Simulator (FDS). 

A FDS model scenario was developed that represented the building geometry, material 

thermal properties, and fire behavior based on information and photographs either gathered 

at the fire scene or provided by the Fire Department of New York and the Bureau of 

Alcohol Tobacco and Firearms (ATF). The results from this model scenario are provided 

in this report. 

The FDS (version 2.0) calculations that best represent the reported fire conditions indicate 

that a fire initially between 500 kW and 2000 kW originating near the rear basement door 

of the hardware store would have generated temperatures sufficient to cause the fusible link 

to release the fire door in less than 130 s. The oxygen concentration profiles suggest that a 

2000 kW fire with the fire door closed could have depleted the oxygen in Unit 20 in less 

than 380 s. A 2000 kW fire with the fire door open would have required more time, 

approximately 650 s, in order to deplete the oxygen in Unit 20 and 22. This limited set of 

fire reconstructions included 500 kW, 1000 kW, and 2000 kW initiating fires in scenarios 

that allowed the fire door to close and in cases where the fire door remained open. This 

range of 500 kW to 2000 kW corresponds to approximately 4 % to 18 % of the organics 

solvents becoming involved in the fire. 

Key Words: cfd models; fire dynamics; fire fatalities; fire fighters; fire investigations; 

fire models; fire simulations; 
2

2. Introduction 

Part of the mission of the Building and Fire Research Laboratory (BFRL) at the National 

Institute of Standards and Technology (NIST) is to conduct basic and applied fire research, 

including fire investigations, for the purposes of understanding fundamental fire behavior 

and to reduce losses from fire. 

On June 17, 2001 a fire and subsequent explosion in the basement of a two story hardware 

store and apartment building in New York claimed the lives of three firefighters. The 

hardware store occupied the first floor and basement of two adjacent units while the 

apartments were located on the second floor above the hardware store. The first floor of 

the hardware store was used as display and retail space while the basement served as 

merchandise storage and assembly/repair area. The fire ignited near the rear door in the 

basement of the first unit and spread through an open doorway into the basement of the 

second unit. Ignition of unburned combustion products and flammable vapors in the 

basement of the second unit resulted in an explosion that generated sufficient pressure to 

lift the floor of the retail space (on the first floor above the basement). The displacement 

of first floor “blew” a fire fighter into the basement from the first floor. The movement of 

the first floor also caused a two-story exterior brick wall to collapse on a number of fire 

fighters. The three fatalities were the fire fighter “blown” into the basement and two fire 

fighters under the collapsed brick wall. 

The National Institute for Occupational Safety and Health (NIOSH) investigates all line-ofduty firefighter deaths and publishes reports on those investigations [1]. At the request of 

the Fire Department of New York (FDNY), NIST has examined the fire dynamics of this 

incident to supplement the FDNY investigation. NIST has performed computer 

simulations of the fire using the newly developed NIST Fire Dynamics Simulator (FDS) 

and Smokeview,∗

 a visualization tool, to provide insight on the fire development and 

thermal conditions that may have existed in the restaurant during the fire. NIST has 

previously used FDS to predict the fire growth in other multiple-fatality fires [2, 3, 4]. This 

report describes the inputs and the results of the NIST FDS (Version 2.0) calculations. 

Three areas of interest that were requested by the FDNY to be reconstructed: 

1. What were the conditions, including temperature and oxygen concentrations, in 

the basements of the two units as the fire spread? 

2. How soon would a fire door between the two basements have closed? 

3. How would different initial heat release rates (500 kW, 1 MW, and 2 MW) 

impact the conditions and fire spread in the basements of the two units? 

 

∗

 Certain commercial equipment, instruments, or materials are identified in this report in order to specify the 

experimental procedure adequately. Such identification is not intended to imply recommendation or 

endorsement by the National Institute of Standards and Technology, nor is it intended to imply that the 

materials or equipment identified are necessarily the best available for the purpose. 
3

3. Fire Incident Summary 

The Fire Department of New York and the Bureau of Alcohol, Tobacco, and Firearms, 

provided this information to NIST on the construction of the hardware store and the events 

that took place during the fire. A summary of the events relevant to developing the FDS 

predictions of the fire follows. 

On the afternoon of June 17, 2001, a fire ignited in the basement area of a hardware store. 

The hardware store occupied the first floor and basement of two adjacent units, 12-20 and 

12-22, while the apartments were located on the second floor above the hardware store. 

The first floor of the hardware store was used as display and retail space while the 

basement served as merchandise storage and repair/assembly area. Facing the front of the 

hardware store, unit 12-20 is on right and unit 12-22 is on the left. The fire started near the 

rear door in the basement of unit 12-20 (Figure 1). 

At 1420, the Queens Communication Office of the Fire Department of New York, received 

a telephone call reporting a fire in the hardware store in unit 12-20. A dispatcher assigned 

an engine company, a ladder company, and a battalion chief to the fire. At 1422, a squad 

company was returning from an earlier call and was driving down the block where the 

hardware store was located. A civilian flagged down the squad company and reported the 

fire. By 1427, at least four ladder companies, two engine companies, one squad company, 

Figure 1. Plan View of the Basement of Hardware Store. 

UP

WH

Merchandise

Stored on

Shelves

Merchandise

Stored on

Shelves

Repair/Assembly

 Area

Rear of Hardware Store

Front of Hardware Store

Fire Door

 Rear

 Doors

(closed)

Basement

Window #1

Basement

Window #2

Stai wr ay

Blocked

Unit 22 Unit 20
4

and a battalion chief were on scene. The second story apartment windows were open, but 

no smoke was coming from the open windows. A ladder company officer chased 

occupants out of the apartments above the hardware store. 

At 1426, forced entry was started on the roll-up doors on the front of the hardware store 

(exposure 1, see Figure 2). Two minutes later at 1428, forced entry of a roll-down gate was 

initiated to provide access to the rear yard of unit 12-20 (exposure 3). At the rear of the 

structure, after forcing the roll-down gate, the ladder company began forcible entry into the 

basement of 12-20 using a saw at 1432. The double set of steel security doors that were 

reinforced with steel bars proved extremely difficult to cut or remove. Entry was less 

difficult in the front where by 1432 the fire fighters had successfully entered the front of 

the store and located an interior stairway to the basement of unit 12-22. At 1433, ladder 

and squad companies inside the front of the store were instructed to hold the interior stairs, 

but not go down them because there was another hose line preparing to enter the basement 

through the rear door. 

At 1435, the forcible entry team started to use a rabbit tool on the rear basement door. 

Members of a squad company and a ladder company joined up inside the front of the hardware store near the interior stairway to the basement. The interior stairway door was 

opened briefly and fire was observed. At the rear of the store at 1437, the use of the rabbit 

tool was not effective in forcing the rear door and the forcible entry team called for a Hurst 

Figure 2. Plan View of Hardware Store Basement with Exposures Defined by Fire Department. 

UP UP

Furnace

Water

Heater

Unit 22 Unit 20

Exposure 3

Exposure 2

Exposure 1

Fire

Door

Interior

Stairway

from First

Floor to

Basement

Blocked

Interior

Stairway

Rear

Doors

Basement

Window #1

Basement

Window #2
5

tool. At the front of the store, the interior team again opened the interior cellar door, 

discovered flames filling the entire door, and opened the nozzle to hit the flames. By 

1440, smoke was observed coming from at least one of the two basement windows on 

exposure 2. 

At 1441, the team inside the front of the store was advised that an interior attack down the 

stairways may be necessary due to difficulties in forcing the rear door. At 1442, the rear 

basement forcible entry team forced the right side of the door open approximately 0.46 m 

(18 inches). By 1445, a ladder company was cutting steel bars behind the rear basement 

door. A number of the fire fighters were working on forcing a second basement window 

on the exposed side. At 1446, the team inside the front of the store reported smelling 

organic vapors (varnish/lacquer/thinner smell). At 1448, an explosion occurred and the 

displacement of the first floor “blew” one fire fighter into the interior stairway near the 

front of the store (exposure 1) and also caused a brick wall to collapse on a number of fire 

fighters that were venting a basement window (exposure 2). Approximate timelines of 

events are given in Table 1 (front) and Table 2 (rear and side). Some of the events listed in 

Tables 1 and 2 were included to provide background information and not all the events 

were included in the computer simulation. 

4. NIST Fire Dynamics Simulator (FDS) 

NIST has developed a computational fluid dynamics (CFD) fire model using large eddy 

simulation (LES) techniques [5]. This model, called the NIST Fire Dynamics Simulator 

(FDS), has been demonstrated to predict the thermal conditions resulting from a compartment fire [6,7]. A CFD model requires that the room or building of interest be divided into 

small three-dimensional rectangular control volumes or computational cells. The CFD 

model computes the density, velocity, temperature, pressure and species concentration of 

the gas in each cell. Based on the laws of conservation of mass, momentum, species, and 

energy the model tracks the generation and movement of fire gases. FDS utilizes material 

properties of the furnishings, walls, floors, and ceilings to compute fire growth and spread. 

A complete description of the FDS model is given in reference [5]. 

For each time step and in each of the computational cells, FDS calculates the gas 

temperature, and concentration of various gases, including oxygen, carbon dioxide, and 

fuel. In order for the gaseous contents of a cell to burn or combust within a cell, there 

must be sufficient fuel and oxygen and the gas temperature must be above a specific 

temperature. For example, if the oxygen concentration drops below 15% and the gas 

temperature is less than 300 °C (570 °F), combustion is not allowed to take place. FDS 

does allow some additional burning with lower oxygen concentrations at higher 

temperatures. The complete oxygen/temperature phase space in which combustion is 

allowed and not allowed to take place is presented and discussed in the Technical 

Reference Guide for FDS [5]. Each cell which meets these requirements (fuel, oxygen, 

and temperature) is allowed to combust for that time step. If the conditions are not met, 

then that cell is not allowed to burn during that time step. 
6

4.1. Model Uncertainty 

FDS can provide valuable insight into how a fire may have developed. However the model 

is only a simulation. The model output is dependent on a variety of input values such as 

material properties, time lines, geometry, and ventilation openings. Since complete knowledge of every detail of the fire site, fuel load or fire timeline is never availableestimations are incorporated into the model. For example, the estimation of the energy 

release rate of an initial “source fire” as a starting point for fire development and spread 

throughout the structure is a necessary part of re-creating this fire scenario. These 

estimations and others used in this simulation are further described in Section 6 of this 

report. These simulations assume a specific fire size and do not consider the origin or 

cause of the fire. These fire reconstructions only model the thermal conditions and oxygen 

concentrations during the fire growth and spread up to 1620 s into the event. FDS is not 

capable of modeling an explosion. 

The ability of the FDS model to predict accurately the temperature and velocity of fire 

gases has been previously evaluated by conducting experiments, both lab-scale and fullscale, and measuring quantities of interest. If an excess of fuel is present or insufficient 

oxygen is available, a fire may be termed as fuel-rich or under-ventilated. If an excess of 

oxygen is present, a fire may be described as fuel-lean or over-ventilated. FDS can predict 

over-ventilated fire conditions better than under-ventilated conditions because underventilated fires require FDS to use an oxygen/temperature relationship to determine when 

combustion is not allowed to occur. For relatively simple fire driven flows, such as 

buoyant plumes and flows through doorways, FDS predictions are within the experimental 

uncertainty of the values measured in the experiments [6]. For example, if a gas flow 

velocity is measured at 0.5 m/s (1.6 ft/s) with an experimental uncertainty of ±0.05 m/s 

(±0.2 ft/s), the FDS model gas flow velocity predictions were also in the range between 

0.45 m/s and 0.55 m/s (1.5 ft/s and 1.8 ft/s). 

In large scale fire tests reported in [7], FDS temperature predictions were found to be 

within 15 % of the measured temperatures and the FDS heat release rates were predicted to 

within 20 % of the measured values. Therefore the results are presented as ranges to 

address these uncertainties. 

5. Smokeview 

Smokeview is a scientific visualization program that was developed to display the results 

of a FDS model computation. Smokeview produces animations or snapshots of FDS 

results [8]. A new feature of Smokeview allows the viewing of FDS output in 3-

dimensional animations. An iso-surface is a three dimensional version of a contour 

elevation often found on topographic maps. For this study, Smokeview determined which 

computational cells met all the requirements for combustion and displayed them as an 

orange/yellow surface. This orange/yellow surface provides a visual simulation of the 

flame surface. The fire source, 500 kW, 1000 kW, or 2000 kW, appears as an inverted 

conical surface. As additional cells meet the requirements for sustaining combustion, the 

orange/yellow surfaces spread across the upper portion of the room. As the fire consumes 
7

Table 1. Approximate Timeline of Events for Front of Hardware Store. 

Time FDS Time 

 s min 

Front of Store 

Exposure 1

1420:52 0 0 Report of fire 

1422:48 56 1 Squad unit drives by fire 

1425:21 

1425:49 

269 

297 

4 

5 

1426 308 5 Squad unit begins cutting roll-up gates at front of store 

1430 548 

 

Team removes roll-up gates for store front 

1431 612 

 

1432 672 11 

1433 732 12 Team reports fire in cellar near rear door. 

Battalion Chief tells team that another line in rear and hold the stairs, do not go down 

1433:45 777 13 Team enters store and goes to rear wall...found inside cellar door 

1434:03 795 

 

Battalion Chief orders two teams to hold interior stairway, but not to go down pending 

rear attack 

1435 852 14 Interior cellar door opened and fire is behind it. Light gray smoke, light blue flame fills 

lower half of door 

1437 972 16 Team opens nozzle to hit flames in inside cellar door, flames fill entire inside cellar 

door 

1439 1092 18 

1442:38 1310 

 

1443 1332 22 

1444 1392 23 Team prepares to go down interior stairs to cellar 

1446 1512 25 Report of varnish/lacquer/thinner smell 

1447:50 1622 27 Explosion occurs. Firefighter “blown” into cellar. 
8

Table 2. Approximate Timeline of Events for Rear and Side of Hardware Store. 

Time FDS Time 

 s min 

Rear of Store 

Exposure 3 

Side of Store 

Exposure 2 

1420:52 0 0 

 

1422:48 56 1 

 

1425:21 

1425:49 

269 

297 

4 

5 

First engine unit arrives. 

Second engine unit arrives 

1426 308 5 

 

1430 548 

 

1431 612 

 

Team starts to force rear cellar door 

1432 672 11 Third unit uses saw on rear door to cellar. Light 

smoke from first floor windows 

1433 732 12 

1433:45 777 13 

1434:03 795 

 

1435 852 14 Forcible entry team use rabbit tool 

1437 972 16 Forcible entry team indicates rabbit tool not 

effective 

1439 1092 18 Hurst tool to rear cellar door FF starts to take rear window on 

exp. 2 

1442:38 1310 

 

Entry team forces right side of rear door open 

18” wide 

1443 1332 22 Team forces rear door. Door partially open, still 

partially blocked. 

Preparing to force second basement 

window 

1444 1392 23 

 

1446 1512 25 

 

1447:50 1622 27 Explosion occurs Explosion occurs. Brick wall 

collapses on firefighters. 
9

the oxygen within the room and fewer computational cells meet the combustion 

requirements, the flame surface appears to retreat or recede. In this report, Smokeview 

was used to generate animated iso-surfaces to visualize the movement and spread of the 

fire within the basement space. 

6. FDS Input 

Inputs required by FDS include the geometry of the structure, the computational cell size, 

the location of the ignition source, the energy release of the ignition source, thermal 

properties of walls, ceilings, floors, furnishings, and the size, location, and timing of door 

and window openings to the outside which critically influence fire growth and spread. The 

timings of the door and window openings used in the simulation are given in Table 2. The 

timings of these events are based on the approximate timeline of the fire events from 

Table 1. These are based on information obtained from Fire Department of New York. 

The size and location of ventilation openings are based on architectural drawings and field 

measurements by Bureau of Alcohol, Tobacco, and Firearms, Fire Department of New 

York, and NIST. 

6.1. Geometry 

The basement floor plan of units 20 and 22 are shown in Figure 3a and 3b. Unit 20 was 

rectangular in shape with dimensions of approximately 17 m x 6 m (55 ft x 20 ft). Unit 22 

was approximately triangular in shape with dimensions of 18.3 m (wall shared with Unit 

20) x 15.8 m (60 ft x 52 ft) and a third side of 22.9 m (75 ft). Floor areas for Unit 20 and 

22 were approximately 100 m2 and 167 m2 (1,100 ft2and 1,800 ft2), respectively. The 

combined floor area for the basement of the hardware store was approximately 270 m2

(2,900 ft2). The bottom of the first floor joists were 2.3 m (92 inches) above the concrete 

floor. The volume of Unit 20 and 22 were 240 m3

 (8450 ft3) and 390 m3 (13,800 ft3), 

respectively. The combined volume for the basement of the hardware store was 

approximately 630 m3 (22,250 ft3). 

For computational purposes the hardware store basement was enclosed within a 35.0 m x 

13.5 m x 5.0 m (114.8 ft x 44.3 ft x 16.4 ft) rectangular volume. For the FDS simulation 

this volume was divided into 734,000 computational cells. The focus of the simulation was 

the spread of the fire from its ignition point and the closure of the fire door. The 

merchandise and shelving were not included in the simulation geometry (Figure 4). The 

computational cells ranged from 125 mm x 255 mm x 125 mm (5.0 in x 10.0 in x 5.0 in) to 

64 mm x 255 mm x 125 mm (2.5 in x 10.0 in x 5.0 in). The cells were smallest near the 

ignition point (Figures 5) and slightly larger in the rest of Unit 20 (Figures 6). The largest 

cells were used to simulate the volume in Unit 22. The size and location of the walls, 

doorways, and windows are adjusted by FDS to correspond to the nearest computational 

cell location (Figure 7). The result is walls and ceilings, used in the model, that appear 

thicker than they are in the actual structure. 
10

6.2. Initial Fire and Fuel Package 

The fire started near the rear door in the basement of Unit 20 (Figure 1). The area near the 

rear door apparently served as a combination shipping/receiving and repair/assembly area 

for the hardware store. It is not clear what item or items ignited first. Packing material 

including used cardboard boxes, wrapping paper, and shipping boxes, may have been 

stacked near the rear door in preparation for disposal. Or, recently delivered merchandise 

or new retail stock may have been located near the rear door prior to restock of the 

merchandise on the first floor retail space. The heat release of several representative fuels, 

including trash bags, wood pallets, newspapers, and cartons, are tabulated in Table 3. 

 After items near the rear door ignited, the fire spread to other merchandise in the basement 

of Unit 20. At least 200 gallons of organic solvents, including acetone, alcohol, naphtha 

and paint thinner were stored near the rear of the basement of Unit 20. Most of the 

solvents were packaged in one gallon containers, although some of the solvents were stored 

in five gallon cans. In addition, up to 300 cans of spray paint (360 g or 12 oz.) were 

located along the common wall between Unit 20 and 22. The energy content of the 

solvents, propane cylinders, and spray paint was estimated in Table 4. Post-fire 

examination of the basements of Unit 20 demonstrated that a number of spray paint cans 

and many of the one gallon (3.78 l) solvent containers had been consumed during the fire. 

Post-fire inspection indicated that most of the one gallon (3.78 l) paint cans stacked near 

the rear door of Unit 20 and additional one gallon cans near the front of Unit 22 were not 

consumed by the fire. The propane cylinders (420 g or 14 oz.) that were removed post-fire 

from the lower shelves in the second row of shelves in Unit 22 were intact and had not 

burst or been consumed by the fire. Those intact propane cylinders appeared to represent a 

majority of the propane cylinders that were inventoried during the post-fire inspection. 

The total heat released during a fire depends on type and quantity of fuels that were 

consumed by the fire. The total heat release rate for different fractions of solvent 

consumed by the fire is estimated in Table 5. If only 1 % of the available organic solvents 

had been consumed by the fire over a period of 30 minutes, then the estimated heat release 

rate was 130 kW. If 30 % of the available solvents had been consumed over the same 30 

minutes then the estimated heat release rate was 3900 kW. It is not clear what percentage 

of the organic solvents and the contents of the spray paint cans were consumed by the fire. 

These estimates do not include the propane cylinders that were located in Unit 22 and 

appeared to have survived the fire intact. Other merchandise would certainly have also 

contributed to the total heat release but are not included in these estimates, so these heat 

release rates are conservative. 

Since the fire model does not have a mechanism to ignite liquid fuel in cans, it is necessary 

to provide the model with a realistic heat release rate and an area in which the heat is released by the burning fuel. A fire consuming approximately 4 %, 9 %, and 18 % of the 

organic solvents and paint would yield total heat release rates of 520 kW, 1010 kW, and 

2020 kW, respectively (Table 5). Fires with 500 kW, 1000 kW, and 2000 kW initial heat 

release rates were selected for the model simulation. Selecting smaller heat release rates 

could cause the gas temperatures in the upper layer to develop more slowly while choosing 
11

Figures 3a and 3b. Basement of Hardware Store Plan View with Dimensions (3a - English 

Units-upper diagram & 3b - Metric Units-lower diagram). 

UP

Unit 22 Unit 20

71' 10"

55' 1"

1800 ft 1100 ft

75'

24' 11"

32"

26' 6"

 8' 20'

5'

UP

Unit 22 Unit 20

21.9 m

16.8 m

167 m 102 m

22.9 m

2 2

 2.44 m

6.1 m

1.52 m

7.6 m

0.8 m

8.1 m
12

Figure 4. Merchandise and Shelving Not Included in Simulation. 

Figure 5. Near the Simulated Fire Source the Simulation Used Smaller Cells (Finer 

Computational Grid). 
13

 

Figure 6. Remote From the Simulated Fire Source the Simulation Used Larger Cells 

(Coarser Computational Grid).

Figure 7. FDS Model Adjusts Walls to Fit Computation Grid and Cells. Note Stepped 

Wall on Upper Left of Diagram. 
14

larger heat release rates could cause the gas temperatures to develop more quickly. A burn 

area of 1 m2 was selected to represent the initial fire burn area. 

For each of the fire scenarios, the selected heat release rate, either 500 kW, 1000 kW, or 

2000 kW, represents the rate at which fuel is supplied to the fire. If there is insufficient 

oxygen or the gas temperature drops too low in any or all of the computational cells, FDS 

does not allow the fuel to burn in those affected cells. However, the unburned fuel 

remains available for combustion if additional oxygen becomes available and/or if gas 

temperature become high enough for FDS to allow combustion. At any given time step, 

FDS calculates the total heat released during that time step by first determining which cells 

will support combustion and then summing the energy released by each of the “allowable” 

cells. 

As the fire burns, it consumes oxygen and fuel. This simulation assumes that the solvents 

and other fuels in the basement provide additional fuels to replace the fuels consumed by 

the fire. The relatively high vapor pressure of the liquid solvents supports the assumption 

that the solvents would be able to evaporate quickly enough to replace the burned fuel. 

The simulation does limit the maximum rate of fuel evaporation by selecting specific heat 

release rates. The simulation assumes that only enough fuel to maintain the specific heat 

release rates is made available at each time step. If one of the solvents, such as acetone, 

evaporates at a higher rate, this simulation does not consider that additional fuel. While in 

these fire scenarios FDS assumed there was an adequate and continuous supply of fuel, 

each fire also required sufficient oxygen. 

If the amount of oxygen is limited, as the fire consumes the available oxygen, the fire will 

decrease in size or “die back” as it becomes “ventilation limited”. However the fuel is 

assumed to continue to evaporate and will accumulate in the room. FDS will not allow 

combustion to occur in cells without sufficient oxygen. If a vent, such as a window or 

door opens, additional oxygen may become available. The additional oxygen may allow 

the fire to grow or increase in terms of heat release rate. 

6.3. Vents 

For the purpose of this simulation, a vent is considered an opening in the building that will 

allow fire gases to exit the structure and/or ambient air from the outside to enter. For this 

simulation, all vents were closed to the outside at the beginning of the simulation. At 

specific times during the simulation, the rear door of Unit 20 and two basement windows in 

Unit 22 were opened. 

As indicated by the estimated timeline (Table 2), the forcible entry team at the rear door of 

Unit 20 was able to partially open the door, approximately 46 cm (18 in), at approximately 

21 minutes. In the simulation, the rear door in the basement of Unit 20 was partially 

opened at 1310 s and this opened a vent 46 cm wide x 203 cm high (18 in x 80in ). 
15

 Figure 8. Location of Paint, Solvents, and Propane in Basement of Hardware Store. 

Also as indicated by the estimated timeline (Table 2), additional fire fighters began to open 

or vent Basement Window #1 and Basement Window #2 at between 17 min and 22 min. 

In the simulation, it was assumed that the fire fighters required about 3 min to open each 

window fully. In each computer run, Window #1 and Window #2 were opened fully at 

22 min (1300 s) and 27 min (1600 s), respectively. Each open window was modeled as an 

open vent with a cross section of 76 cm wide x 46 cm high (30” x 18”). 

6.4. Openings Within the Structure 

An opening in the common wall between Unit 20 and Unit 22 allowed easy movement 

between the two basements. This opening was equipped with a fire door which was 

designed to close in case of fire. The door itself was located next to this opening and just 

inside Unit 20 (See Figures 2 and 4). A fusible link that was rated at 74 °C (165 °F) was 

located near the ceiling and held the fire door in a retracted position. Upon exposure to 

UP

WH

Rear of Hardware Store

Front of Hardware Store

Fire Door

Rear

Doors

Stai wr ay

Blocked

Unit 22 Unit 20

Spray Paint

Cans (12 oz.)

 Bulk

Solvents

 Paint Cans

 (1 gallon)

Propane

Cylinders

(14 oz.)

 Paint Cans

 (1 gallon)
16

sufficiently high temperatures, this link would soften or fuse and allow the door to move 

across the opening and close the doorway. The fire door was allowed to close in three of 

the computer simulations and was not allowed to close in the other three recreations. 

The thermal performance or activation of several Underwriters Laboratory (UL) listed 

fusible links (designed for fire vents) were examined by McGrattan et al. [9]. For this 

simulation, it was assumed that the fire door fusible link behaved in a similar manner and 

after the link reached 74 °C (165 °F) and remained at that temperature for 65 s, the link 

would fuse or melt. Once the link was fused, the link would release the door and allow it 

to close. 

As the fire door closed, approximately 60 % of the volume and therefore the oxygen 

became less available to the fire burning in Unit 20. In the open door simulation, the fire in 

Unit 20 could have drawn fresh air and oxygen from Unit 22 while hot combustion gases 

and unburned hydrocarbons would have flowed into Unit 22. How much oxygen was or 

was not available to the fire would have significantly impacted how fast the fire would 

have grown and spread in the basement of Unit 20 and eventually extended into Unit 22. 

Table 3. Total Heat Release for a Number of Fuels [10]. 

Fuel 

Heat 

Release 

Rate 

kW 

Total 

Heat 

Release1

kJ 

Burn 

Duration2

s 

 Comments 

Trash Bags 0.6 120 200 s 1.2 kg cellulosic trash 

1.8 360 200 s 14 kg cellulosic trash 

Newspaper 0.04 4 100 s Folded, 22 g 

0.9 18 20 s Crumpled, 22 g 

Wood Pallets 1.3 200 150 s 0.55m (18”) high stack 3

1.3 400 310 s 0.55 m (18”) high stack 

Mail Bags, 0.4 40 100 s 

filled3

0.4 80 200 s 

Cartons, stacked, 2.3 35 15 s 

compartmented3

2.3 70 30 s 

Plastic Toy Parts 2.1 210 100 s Polystyrene Plastic 

in cartons3

2.1 420 200 s Polystyrene Plastic 

1

 Total Heat Release = Heat Release Rate x Burn Duration. 

2 Burn duration is time duration of significant burning 

3

 Assumes burn area of 1 m2 ( 40 in x 40 in). 
17

Table 4. Estimated Energy Content of Solvents in Basement of Hardware Store 

Fuel Estimated 

 Inventory 

 Liters Gallons 

Estimated 

 Energy Content 

 MJ/kg MJ/gallon 

Estimated Total 

Energy Content 

MJ 

Acetone 45 12 30.83 92 1100 

Denatured Alcohol 91 24 29.67 89 2100 

E-Z Alcohol 45 12 33.38 99 1200 

Lacquer Thinner 91 24 90 1 2200 

Methyl Ethyl Ketone 91 24 33.9 103 2500 

Mineral Spirits 91 24 90 1 2200 

Naphtha 91 24 90 1 2200 

Paint Thinner 91 24 90 1 2200 

Toluene 15 4 42.4 139 560 

Turpentine 91 24 90 1 2200 

Xylene 15 4 42.9 143 570 

 Volume Number MJ/ kg MJ/container 

 

Propane Cylinder 0.42 kg 

(14 oz.)

142 50.35 21 3000 

Spray Paint Aerosol Can 0.36 kg 

(12 oz.)

300 50.35 2 18 1360 

1

 These solvents are mixtures of linear and branched alkanes, cycloalkanes, and aromatic 

hydrocarbons. Their energy content was approximated by assuming a value of 

23.8 MJ/ liter (90 MJ/gallon) 

2

 Spray Paint Aerosol Can was assumed to be 75 % paint compounds and 25 % propane 

propellant. Energy content was approximated by assuming the value for propane for 25 % of 

the mass of each can. 
18

Table 5. Estimated Heat Release Rate for Fraction of Solvent Consumed by Fire. 

Fuel Estimated 

 Inventory 

 Liters Gallons

 Estimated Heat Release Rate 1

 

Fraction of Solvent Consumed by Fire 

 1 % 2 % 4 % 9 % 18 % 30 % 

 kW kW kW kW kW kW 

Acetone 45 12 6 2 12 25 55 111 185 

Denatured Alcohol 91 24 12 24 47 106 213 355 

E-Z Alcohol 45 12 7 13 26 60 119 198 

Lacquer Thinner 91 24 12 24 48 108 216 360 

Methyl Ethyl Ketone 91 24 14 28 55 124 248 413 

Mineral Spirits 91 24 12 24 48 108 216 360 

Naphtha 91 24 12 24 48 108 216 360 

Paint Thinner 91 24 12 24 48 108 216 360 

Toluene 15 4 3 6 12 28 56 93 

Turpentine 91 24 12 24 48 108 216 360 

Xylene 15 4 3 6 13 29 57 95 

 

 Container Number 

Spray Paint Aerosol 

Can 

0.36 kg 

(12 oz.)

300 8 15 30 68 136 227 

 

 Total Heat Release Rate 3 130 260 520 1010 2020 3900 

 Container Number 

Propane Cylinder4 0.42 kg 

(14 oz.) 

142 17 33 67 150 300 500 

1 Solvent consumed during a 30 min period.

2 If a fire consumed 1% of the Acetone in the basement during a 30 min period, then that amount of acetone 

would contribute 6 kW to the heat release rate.

3 Summing the contributions of each of the individual solvents provides an estimate of the total heat release 

rate.

4 Propane Cylinders were located in basement of Unit 22 and were not included in the estimate of Total Heat 

Release Rate for Unit 20.
19

Table 6. Time of Ventilation Events for FDS Simulation 

 

Fire Door 

Allowed 

 to Close 

Fire Door 

Remained 

Open 

Vent Initial 

Conditions Time of Event, s 

Rear Door 

Unit 20 Closed 1310 Partially Open 

1310 

Partially Open 

Basement Window # 1 

Unit 22 Closed 1300 Fully Open 

1300 

Fully Open 

Basement Window # 2 

Unit 22 Closed 1600 Fully Open 

1600 

Fully Open 

Note – Partially Open = Rear door was opened 46 cm (18 in). 

6.5. Material Properties 

When a wall, ceiling, truss, piece of furniture, or any other structural item or piece of 

furniture is defined for use in the FDS model it is given a set of physical and thermal 

properties that are used by the model. A list of the materials used in these simulations 

along with the physical and thermal properties required by FDS is given in Table 7 [5]. The 

first floor joists and subfloor used in this structure were made of wood. In the simulation 

these wooden components were given the thermal characteristics of oak. The floor joists 

were assigned a thickness of 0.1 m ( 4 in). The under side of the first floor or the subfloor 

was assigned a thickness of 0.02 m ( 0.75 in). The floor and walls in both basements were 

given the thermal characteristics of concrete with a thickness of 0.2 m ( 8 in). The thermal 

properties of the materials were used by FDS to calculate heat transfer and determine when 

these materials ignite and their contribution to the heat release rate of the fire. 
20

Table 7. Thermal Properties Data 

 

 Material 

Thermal Property Units 

Floor and Walls 

Concrete 

Wood Components 

Hardwood – Oak 

Thickness m 0.20 0.02 (subfloor) 

0.1 (joists) 

Ignition Temperature °C Not applicable 340 

Thermal Conductivity W/m K 1.0 0.17 

Thermal Diffusivity m2

/s 5.7 x 10-7 8.9 x 10-8

Heat of Vaporization kJ/kg Not applicable 4000 

Heat of Combustion kJ/kg Not applicable 13000 

7. Model Results 

The fire spread and growth in the basement of the hardware store was simulated using three 

different initial fire heat release rates: 500 kW, 1000 kW, and 2000 kW. Each different 

heat release rate was replicated with the fire door open (not allowed to close when fusible 

link melted) and the fire door closed (allowed to close when fusible link softened or 

melted). For each simulation, the temperature and oxygen concentration was tracked at 

different locations within Unit 20 and Unit 22. 

7.1. Model Geometry and Iso-Surfaces Output 

Figure 9 displays the view generated within the model simulation from the front of Unit 20 

looking towards the rear door. For each case, the fire was positioned just inside the rear 

basement door for Unit 20 and is outlined as a square on the floor in Figure 10. 

Figures 11 - 22 show plots of iso-surfaces for an initial 500 kW fire source with the door 

open. Iso-surfaces are calculated by FDS at locations where the mixture of fuel and 

oxygen are sufficient to support combustion. While not precise, iso-surfaces can provide a 

qualitative feel for where the fire might be burning. In this simulation, Basement 

Window #1 was opened at 1300 s and the rear door was partially opened at simulation time 

of 1310 s. The model simulation indicates that as the additional oxygen entered the 

basement of Unit 20 additional burning occurred (compare Figure 19 at 1311 s and Figure 

20 at 1324 s). The orange/yellow “flame” surface spreads across the ceiling as the 
21

Figure 9. View Generated by Model Simulation Looking from Front of Unit 20 

Towards Rear Door. Fire Door Opening Located in Wall on Left. Note Red Dot 

at Upper Right Corner of Fire Door Opening. Red Dot Indicates Position of Fire 

Door Thermocouple (next to location of fusible link). 

Figure 10. Fire Positioned Just Inside Rear Door of Unit 20. 
22

Figure 11. Iso-Surface Plot for an Initial 

500 kW Fire Source. Fire at Time = 0 s. 

Figure 12. Iso-Surface Plot for an Initial 

500 kW Fire Source. Fire at Time = 16 s.

Figure 13. Iso-Surface Plot for an Initial 

500 kW Fire Source. Fire at Time = 33 s. 

Figure 14. Iso-Surface Plot for an Initial 

500 kW Fire Source. Fire at Time = 62 s.

Figure 15. Iso-Surface Plot for an Initial 

500 kW Fire Source. Fire at Time = 120 s. 

Figure 16. Iso-Surface Plot for an Initial 

500 kW Fire Source. Fire at Time = 300 s. 
23

Figure 17. Iso-Surface Plot for an Initial 

500 kW Fire Source. Fire at Time = 600 s. 

Figure 18. Iso-Surface Plot for an Initial 

500 kW Fire Source. Fire at Time = 1200 s. 

Figure 19. Iso-Surface Plot for an Initial 

500 kW Fire Source. Fire at Time = 1311 s. 

Figure 20. Iso-Surface Plot for an Initial 

500 kW Fire Source. Fire at Time = 1324 s. 

Figure 21. Iso-Surface Plot for an Initial 

500 kW Fire Source. Fire at Time = 1592 s. 

Figure 22. Iso-Surface Plot for an Initial 

500 kW Fire Source. Fire at Time = 1629 s. 
24

additional oxygen flows through the basement and allows more of the computational cells 

to meet the requirements for combustion. However, once the oxygen and fuel are 

consumed or the gas temperature drops low enough, the cells no longer meet the 

requirements for combustion, so less heat is released. Over the next 450 s, the fire 

decreases or “dies back” and the orange/yellow flame retreats back to a fire near the rear 

door of Unit 20 as shown in the iso-surface plot at 1592 s (Figure 21). 

7.1. Fire Simulation –Temperature and Oxygen Concentration 

Predictions 

The Fire Dynamic Simulator computer model calculates the velocity, direction, 

temperature, and composition of the combustion gases, smoke density, and thermal 

radiation, material ignition and heat release rate within each computational cell (see 

Figures 5 and 6) for each time step during the simulation. This data can be displayed as a 

slice that extends front to back or side to side of the structure. For this reconstruction, the 

gas temperatures and oxygen concentrations were recreated using FDS. A sliding color 

scale can help the reader to visualize the distribution of temperatures or oxygen 

concentration across the basement of Unit 20 and 22. 

For each oxygen data slice, the lower end of the color bar, blue, corresponds to zero 

oxygen concentration while the upper end, red, matches up with ambient 21 % oxygen 

(0.21 mol concentration of oxygen). As each fire grows, it consumes oxygen and the color 

changes from red (21 % oxygen) to blue (zero oxygen). At some point in the fire growth, 

the lack of oxygen will slow the growth of the fire and if additional oxygen is not provided, 

the fire will stop burning. If a vent, such as a door is opened, then additional oxygen may 

flow into the room and the color would change from blue to green to yellow and eventually 

to red as the oxygen concentrations reach 21 %. If the fire door has closed and isolated 

Unit 20 from Unit 22, then the oxygen concentrations could be significantly different in the 

two units. 

For each temperature data slice, the lower end of the color bar, blue, corresponds to less 

than 20 °C (68 °F ) or gas at ambient room temperature while the upper end, red, matches 

up with the highest gas temperature for that specific fire. Any gas temperature higher than 

the maximum temperature on the color scale is displayed as red. For example, if the color 

bar ranges from 20 °C to 340 °C (68 °F to 644 °F), and the flame zone reached gas 

temperatures of 1200 °C (2200 °F), the flame zone would be colored red. As each fire 

grows, the gas temperatures increase and change from blue to green to yellow and finally to 

red. If the fire becomes ventilation limited, too little oxygen or too much fuel, then the fire 

could stop growing and may extinguish itself. In this case, the gas temperatures would 

start cool (blue) and increase to hot (red) and then might cool down again (blue). If the fire 

door has closed and isolated Unit 20 from Unit 22, then the gas temperatures could be 

significantly different in the two units. 

Fire Simulations With Fire Door Allowed to Close – 500 kW, 1000 kW, and 2000 kW 

Figures 23 through 32 show the temperatures and oxygen concentrations in Unit 20 and 22 

for an initial 500 kW fire source at times of 118 s, 126 s, 586 s, and 1088 s. Each gas 
25

temperature plot on the left is paired with its corresponding oxygen concentration plot on 

the right side. The fire door is open initially and as the fire grows the gas temperatures 

reach high enough values to melt or fuse the fusible link and the door closes at 126 s. The 

closed fire door appears as a solid blue surface in the temperature slices and as a solid blue 

rectangle in the oxygen slices. The temperature of a simulated thermocouple placed near 

the fusible link was tracked throughout the fire and used to determine when the fusible link 

might soften or melt and release the fire door. In the temperature slice figures, the 

thermocouple near the fusible link is visible as a small green square at the upper rear corner 

of the fire door. The thermocouple temperatures near the fusible link will be discussed 

later in this report. 

As can be observed from the temperature slices, the fire develops gas temperatures near the 

center of Unit 20 in excess of 200 °C (392 °F) in less than 120 s. These high temperatures 

are sufficient to cause the fire door to close. By 586 s, the gas temperatures are decreasing significantly until by 1088 s, the gas temperatures in most of Unit 20 appear near 

20 °C (68 °F). The oxygen slices demonstrate that in the beginning, the fire can draw 

oxygen from Unit 20 and 22, but after 126 s, the fire only has access to the oxygen 

Figure 23. Temperature Profiles for an Initial 

500 kW Fire Source. Fire At Time = 118 s. 

Figure 24. Oxygen Concentrations for an Initial 

500 kW Fire Source. Fire At Time = 118 s. Fire 

Door is Open. 

Figure 25. Temperature Profiles for an 

Initial 500 kW Fire Source. Fire At Time = 

126 s. Fire Door Closed at 126 s. 

Figure 26. Oxygen Concentrations for an 

Initial 500 kW Fire Source. Fire At 

Time = 126 s. Fire Door Closed at 126 s. 
26

Figure 27. Temperature Profiles for an 

Initial 500 kW Fire Source. Fire At 

Time = 236 s. Fire Door Closed at 126 s. 

Figure 28. Oxygen Concentrations for an 

Initial 500 kW Fire Source. Fire At 

Time = 236 s. Fire Door Closed at 126 s. 

Figure 29. Temperature Profiles for an 

Initial 500 kW Fire Source. Fire At 

Time = 586 s. Fire Door Closed at 126

Figure 30. Oxygen Concentrations for an 

Initial 500 kW Fire Source. Fire At 

Time = 586 s. Fire Door Closed at 126 s. 

Figure 31. Temperature Profiles for an 

Initial 500 kW Fire Source. Fire At Time 

= 1088 s. Fire Door Closed at 126 s. 

Figure 32. Oxygen Concentrations for an 

Initial 500 kW Fire Source. Fire At 

 Time = 1088 s. Fire Door Closed at 126 s. 
27

in Unit 20. By 375 s, the fire has consumed enough oxygen to reduce the concentration 

below the 15% concentration necessary to allow combustion below 300 °C (570 °F) in Unit 

20. While FDS does allows some additional burning to occur at lower oxygen 

concentrations and higher temperatures, the unburned fuel is still accumulating in Unit 20. 

By 586 s, the fire has dropped the oxygen concentrations to less than 10 % and appears to 

have consumed all the oxygen in the rear of Unit 20 by 1088 s. 

Figures 33 through 44 show the temperatures and oxygen concentrations in Unit 20 and 22 

for a 1000 kW fire at times of 73 s, 81 s, 126 s, 224 s, 428 s, and 767 s. The fire door is 

open initially and as the fire grows the gas temperatures reach high enough values to soften 

or melt the fusible link and the door closes at 81 s. 

As can be observed from the temperature slices, the fire develops gas temperatures near the 

center of Unit 20 in excess of 200 °C (392 °F) in less than 120 s. These high temperatures 

are sufficient to cause the fire door to close. By 428 s, the gas temperatures are 

decreasing significantly until by 767 s, most of the gas temperatures in Unit 20 appear near 

20 °C (68 °F). As one might expect, the higher heat release fire, 1000 kW instead of 500 

kW, causes the gas temperatures to increase more quickly and the oxygen to be consumed 

more quickly. The oxygen slices demonstrate that in the beginning, the fire can draw 

oxygen from Unit 20 and 22, but after 81 s, the fire only has access to the oxygen in Unit 

20. By 204 s, the fire has consumed enough oxygen to reduce the concentration below the 

15% concentration necessary to allow combustion below 300 °C (570 °F) in Unit 20. 

While FDS does allows some additional burning to occur at lower oxygen concentrations 

and higher temperatures, the unburned fuel is still accumulating in Unit 20. By 428 s, the 

fire has dropped the oxygen concentrations to less than 6 % and appears to have consumed 

all the oxygen in the rear of Unit 20 by 767 s. 

Figures 45 through 54 show the temperatures and oxygen concentrations in Unit 20 and 22 

for a 2000 kW fire at times of 53 s, 57 s, 90 s, 183 s, and 375 s. The fire door is open 

initially and as the fire grows the gas temperatures reach high enough values to activate the 

fusible link and the door closes at 57 s. 

As can be observed from the temperature slices, the fire develops gas temperatures near the 

center of Unit 20 in excess of 200 °C (392 °F) in less than 60 s. These high temperatures 

are sufficient to cause the fire door to close. By 183 s, the gas temperatures are 

decreasing significantly until by 375 s, most of the gas temperatures in Unit 20 appear less 

than 150 °C (300 °F). As one might expect, the higher heat release fire, 2000 kW instead 

of 500 kW or 1000 kW, causes the gas temperatures to increase more quickly and the 

oxygen to be consumed more quickly. The oxygen slices demonstrate that in the beginning, the fire can draw oxygen from Unit 20 and 22, but after 57 s, the fire only has access 

to the oxygen in Unit 20. By 130 s, the fire has consumed enough oxygen to reduce the 

concentration below the 15% concentration necessary to allow combustion below 300 °C 

(570 °F) in Unit 20. While FDS does allows some additional burning to occur at lower 

oxygen concentrations and higher temperatures, the unburned fuel is still accumulating in 

Unit 20. By 183 s, the fire has dropped the oxygen concentrations to less than 6 % and 

appears to have consumed all the oxygen in the rear of Unit 20 by 375 s. 
28

Figure 33. Temperature Profiles for an 

Initial 1000 kW Fire Source. Fire At 

 Time = 73 s. Fire Door is Open. 

Figure 34. Oxygen Concentrations for an 

Initial 1000 kW Fire Source. Fire At 

Time = 73 s. Fire Door is Open. 

Figure 35. Temperature Profiles for an 

Initial 1000 kW Fire Source. Fire At 

Time = 81 s. Fire Door Closed at 81 s. 

Figure 36. Oxygen Concentrations for an 

Initial 1000 kW Fire Source. Fire At 

Time = 81 s. Fire Door Closed at 81 s. 

Figure 37. Temperature Profiles for an 

Initial 1000 kW Fire Source. Fire At 

Time = 126 s. Fire Door Closed at 81 s. 

Figure 38. Oxygen Concentrations for an 

Initial 1000 kW Fire Source. Fire At 

Time = 126 s. Fire Door Closed at 81 s. 
29

Figure 39. Temperature Profiles for an 

Initial 1000 kW Fire Source. Fire At 

Time = 224 s. Fire Door Closed at 81 s. 

Figure 40. Oxygen Concentrations for an 

Initial 1000 kW Fire Source. Fire At 

Time = 224 s. Fire Door Closed at 81 s.

Figure 41. Temperature Profiles for an 

Initial 1000 kW Fire Source. Fire At 

Time = 428 s. Fire Door Closed at 81 s. 

Figure 42. Oxygen Concentrations for an 

Initial 1000 kW Fire Source. Fire At 

Time = 428 s. Fire Door Closed at 81 s. 

Figure 43. Temperature Profiles for an 

Initial 1000 kW Fire Source. Fire At 

Time = 767 s. Fire Door Closed at 81 s. 

Figure 44. Oxygen Concentrations for an 

Initial 1000 kW Fire Source. Fire At 

Time = 767 s. Fire Door Closed at 81 s. 
30

Figure 45. Temperature Profiles for an 

Initial 2000 kW Fire Source. Fire At 

Time = 53 s. Fire Door is Open. 

Figure 46. Oxygen Concentrations for an 

Initial 2000 kW Fire Source. Fire At 

Time = 53 s. Fire Door is Open. 

Figure 47. Temperature Profiles for an 

Initial 2000 kW Fire Source. Fire At 

Time = 57 s. Fire Door Closed at 57 s. 

Figure 48. Oxygen Concentrations for an 

Initial 2000 kW Fire Source. Fire At 

Time = 57 s. Fire Door Closed at 57 s. 

Figure 49. Temperature Profiles for an 

Initial 2000 kW Fire Source. Fire At 

Time = 90 s. Fire Door Closed at 57 s. 

Figure 50. Oxygen Concentrations for an 

Initial 2000 kW Fire Source. Fire At 

Time = 90 s. Fire Door Closed at 57 s. 
31

Fire Simulations With Fire Door Not Allowed to Close – 500 kW, 1000 kW, 

 and 2000 kW 

Figures 55 through 64 show the temperatures and oxygen concentrations in Unit 20 and 22 

for an initial 500 kW fire source at time steps of 120 s, 128 s, 235 s, 566 s, and 1088 s. 

Each gas temperature plot on the left is paired with its corresponding oxygen concentration 

plot on the right side. The fire door is open initially and the closing mechanism is disabled 

so that the fire door is not allowed to close. Even though the fire door could not close, the 

fusible link thermocouple temperatures were calculated and will be discussed later in this 

report. As can be observed from the temperature slices, the fire develops gas temperatures 

near the center of Unit 20 in excess of 200 °C (392 °F) in less than 120 s. Since the fire 

door is not permitted to close, some of the hot gases flow from Unit 20 into Unit 22. 

Fresh cool air from Unit 22 also flowed back to Unit 20 and provided dilution air as well as 

additional oxygen for the fire. As compared to the 500 kW fire (Figures 23 – 32) where 

Figure 51. Temperature Profiles for an 

Initial 2000 kW Fire Source. Fire At 

Time = 183 s. Fire Door Closed at 57 s. 

Figure 52. Oxygen Concentrations for an 

Initial 2000 kW Fire Source. Fire At 

Time = 183 s. Fire Door Closed at 57 s. 

Figure 53. Temperature Profiles for an 

Initial 2000 kW Fire Source. Fire At 

Time = 375 s. Fire Door Closed at 57 s. 

Figure 54. Oxygen Concentrations for an 

Initial 2000 kW Fire Source. Fire At 

Time = 375 s. Fire Door Closed at 57 s. 
32

the fire door closed at 126 s, the gas temperatures in this case increase more quickly and 

appear to reach the higher peak values (note change in temperature corresponding to red 

color). By 1221 s, the gas temperatures are not quite as uniform as in the closed door case, 

but still most of Unit 20 appears near 20 °C (68 °F). The oxygen slices demonstrate that in 

the beginning the fire can draw oxygen from Unit 20 and 22, and by 235 s, a significant 

amount of the oxygen near the rear of Unit 22 has been consumed by the fire. By 970 s, the 

fire has consumed enough oxygen to reduce the concentration below the 15 % concentration necessary to allow combustion below 300 °C (570 °F) in Unit 20 and 22. While FDS 

does allows some additional burning to occur at lower oxygen concentrations and higher 

temperatures, the unburned fuel is still accumulating in Unit 20. After 1221 s, the fire has 

dropped the oxygen concentrations to less than 10 % in the rear of Unit 20 and Unit 22. 

Figures 65 through 78 show the temperatures and oxygen concentrations in Unit 20 and 22 

for an initial 1000 kW fire source at time steps of 74 s, 82 s, 128 s, 223 s, 429 s, 788 s, and 

1270 s. The fire door is open initially and the closing mechanism is disabled so that the 

fire door is not allowed to close. 

As can be observed from the temperature slices, the fire develops gas temperatures near the 

center of Unit 20 in excess of 200 °C (392 °F) in less than 120 s. The flow of hot 

combustion gases from Unit 20 into Unit 22 and the stream of cool air from Unit 22 into 

Unit 20 is again apparent. As one would expect the gas temperatures appear to increase 

more quickly as compared to the 500 kW door open case. But as compared to the 1000 kW 

fire (Figures 33 – 44) where the fire door closed at 81 s, the gas temperatures in this case 

also increase more quickly and appear to reach the higher peak values (note change in 

temperature corresponding to red color). By 1270 s, most of the gas temperatures in the 

rear of Unit 20 appear near 20 °C (68 °F). The oxygen slices demonstrate that the fire can 

draw oxygen from Unit 20 and 22, and by 429 s, a significant amount of the oxygen near 

the rear of Unit 22 has been consumed by the fire. By 550 s, the fire has consumed enough 

oxygen to reduce the concentration below the 15 % concentration necessary to allow 

combustion below 300 °C (570 °F) in Unit 20 and 22. While FDS does allows some 

additional burning to occur at lower oxygen concentrations and higher temperatures, the 

unburned fuel is still accumulating in Unit 20 and 22. After 1270 s, the fire has dropped 

the oxygen concentrations to less than 10 % in the rear of Unit 20 and Unit 22. As 

compared to the 1000 kW closed door case, the fire in this case does not lower the oxygen 

concentration as quickly, but this would be expected since the oxygen in both Unit 20 and 

22 would be available to the fire. Also as one would expect when comparing the 500 kW 

and 1000 kW open door cases, the higher heat release rate fire was able to deplete the 

oxygen in the rear of both units more quickly than the smaller fire. 

Figures 79 through 90 show the temperatures and oxygen concentrations in Unit 20 and 22 

for an initial 2000 kW fire source at times of 54 s, 58 s, 87 s, 166 s, 375 s, and 644 s. The 

fire door is open initially and the closing mechanism is disabled so that the fire door is not 

allowed to close. 
33

Figure 55. Temperature Profiles for an Initial 

500 kW Fire Source. Fire At Time = 120 s. 

Fire Door is Open and Closing Mechanism 

Disabled. 

Figure 56. Oxygen Concentrations for an 

Initial 500 kW Fire Source. Fire At Time = 

120 s. Fire Door is Open and Closing 

Mechanism Disabled. 

Figure 57. Temperature Profiles for an Initial 

500 kW Fire Source. Fire At Time = 128 s. 

Fire Door is Open and Closing Mechanism 

Disabled. 

Figure 58. Oxygen Concentrations for an Initial 

500 kW Fire Source. Fire At Time = 128 s. Fire 

Door is Open and Closing Mechanism Disabled. 

Figure 59. Temperature Profiles for an Initial 

500 kW Fire Source. Fire At Time = 235 s. 

Fire Door is Open and Closing Mechanism 

Disabled. 

Figure 60. Oxygen Concentrations for an Initial 

500 kW Fire Source. Fire At Time = 235 s. Fire 

Door is Open and Closing Mechanism Disabled. 
34

Figure 61. Temperature Profiles for an Initial 

500 kW Fire Source. Fire At Time = 566 s. 

Fire Door is Open and Closing Mechanism 

Disabled. 

Figure 62. Oxygen Concentrations for an Initial 

500 kW Fire Source. Fire At Time = 566 s. Fire 

Door Open and Closing Mechanism Disabled. 

Figure 63. Temperature Profiles for an Initial 

500 kW Fire Source. Fire At Time = 1221 s. 

Fire Door Open and Closing Mechanism 

Disabled. 

Figure 64. Oxygen Concentrations for an Initial 

500 kW Fire Source. Fire At Time = 1221 s. 

Fire Door is Open and Closing Mechanism 

Disabled. 

Figure 65. Temperature Profiles for an 

Initial 1000 kW Fire Source. Fire At 

Time = 74 s. Fire Door Open. 

Figure 66. Oxygen Concentrations for an 

Initial 1000 kW Fire Source. Fire At 

Time = 74 s. Fire Door is Open. 
35

Figure 67. Temperature Profiles for an 

Initial 1000 kW Fire Source. Fire At 

Time = 82 s. Fire Door Open and Closing 

Mechanism Disabled. 

Figure 68. Oxygen Concentrations for an 

Initial 1000 kW Fire Source. Fire At 

Time = 82 s. Fire Door is Open and Closing 

Mechanism Disabled. 

Figure 69. Temperature Profiles for an 

Initial 1000 kW Fire Source. Fire At 

Time = 128 s. Fire Door Open and Closing 

Mechanism Disabled. 

Figure 70. Oxygen Concentrations for an 

Initial 1000 kW Fire Source. Fire At Time = 

128 s. Fire Door is Open and Closing 

Mechanism Disabled. 

Figure 71. Temperature Profiles for an 

Initial 1000 kW Fire Source. Fire At 

Time = 223 s. Fire Door Open and Closing 

Mechanism Disabled. 

Figure 72. Oxygen Concentrations for an 

Initial 1000 kW Fire Source. Fire At 

Time = 223 s. Fire Door is Open and 

Closing Mechanism Disabled. 
36

Figure 73. Temperature Profiles for an 

Initial 1000 kW Fire Source. Fire At 

Time = 429 s. Fire Door Open and Closing 

Mechanism Disabled. 

Figure 74. Oxygen Concentrations for an 

Initial 1000 kW Fire Source. Fire At 

Time = 429 s. Fire Door is Open and 

Closing Mechanism Disabled. 

Figure 75. Temperature Profiles for an Initial 

1000 kW Fire Source. Fire At Time = 788 s. 

Fire Door Open and Closing Mechanism 

Disabled. 

Figure 76. Oxygen Concentrations for an Initial 

1000 kW Fire Source. Fire At Time = 788 s. Fire 

Door is Open and Closing Mechanism Disabled. 

Figure 77. Temperature Profiles for an Initial 

1000 kW Fire Source. Fire At Time = 1270 s. 

Fire Door Open and Closing Mechanism 

Di bl d

Figure 78. Oxygen Concentrations for an Initial 

1000 kW Fire Source. Fire At Time = 1270 s. Fire 

Door is Open and Closing Mechanism Disabled. 
37

As can be observed from the temperature slices, the fire develops gas temperatures near the 

center of Unit 20 in excess of 200 °C (392 °F) in less than 90 s. The flow of hot 

combustion gases from Unit 20 into Unit 22 and the stream of cool air from Unit 22 into 

Unit 20 is again apparent. As one would expect the gas temperatures appear to increase 

more quickly as compared to the 500 kW and 1000 kW door open cases. But as compared 

to the 2000 kW fire (Figures 65 – 78) where the fire door closed at 57 s, the gas 

temperatures in this case also increase more quickly and appear to reach the higher peak 

values (note change in temperature corresponding to red color). By 644 s, most of the gas 

temperatures in the rear of Unit 20 appear less than 100 °C (212 °F). The oxygen slices 

demonstrate that the fire can draw oxygen from Unit 20 and 22, and by 166 s, a significant 

amount of the oxygen near the rear of Unit 22 has been consumed by the fire. By 310 s, 

the fire has consumed enough oxygen to reduce the concentration below the 15 % 

concentration necessary to allow combustion below 300 °C (570 °F) in Unit 20 and 22. 

While FDS does allows some additional burning to occur at lower oxygen concentrations 

and higher temperatures, the unburned fuel is still accumulating in Unit 20 and 22. After 

644 s, the fire has dropped the oxygen concentrations to less than 12 % in the rear of Unit 

20 and Unit 22. As compared to the 2000 kW closed door case, the fire in this case does 

not lower the oxygen concentration as quickly, but this would be expected since the oxygen 

in both Unit 20 and 22 would be available to the fire. Also as one would expect when 

comparing the 500 kW, 1000 kW, and 2000 kW open door cases, the highest heat release 

rate fire was able to deplete the oxygen in the rear of both units more quickly than either of 

the smaller fires. 

As demonstrated by this limited set of gas temperature and oxygen concentration slice data, 

the 2000 kW fires overall resulted in higher temperatures and depleted the oxygen more 

quickly than either the 1000 kW or 500 kW fires. As compared to the closed door cases, 

the open door case fires required more time to deplete the oxygen in the rear of Unit 20, but 

the open door cases produced higher temperatures along the centerline of Unit 20. 

7.2 Fire Door Activation 

For each closed or open door cases, 500 kW, 1000 kW, and 2000 kW fires, the gas 

temperature near the fusible link was monitored throughout each fire simulation. For each 

case, the gas temperature was plotted versus time for 1620 s of fire reconstruction. The 

gas temperatures are plotted in both Centigrade and Fahrenheit temperatures. For each of 

the closed door reconstructions, the time when the fire door closed is indicated on the data 

plot. The time that is indicated on each plot is when the fusible link released the door (after 

the link reached 74 °C (165 °F) and remained at that temperature for 65 s). Once the link 

was softened or melted, the link would release the door and allow it to close. For each of 

the open door cases, the opening of the two basement windows in Unit 22 and the rear door 

in Unit 20 are indicated. For the open door reconstructions, the introduction of additional 

air via the rear door and basement windows causes the fire to begin to grow again. 
38

Figure 81. Temperature Profiles for an 

Initial 2000 kW Fire Source. Fire At 

Time = 58 s. Fire Door Open and 

Closing Mechanism Disabled. 

Figure 82. Oxygen Concentrations for an 

Initial 2000 kW Fire Source. Fire At 

Time = 58 s. Fire Door is Open and Closing 

Mechanism Disabled. 

Figure 83. Temperature Profiles for an Initial 

2000 kW Fire Source. Fire At Time = 87 s. 

Fire Door Open and Closing Mechanism 

Disabled. 

Figure 84. Oxygen Concentrations for an 

Initial 2000 kW Fire Source. Fire At Time = 

87 s. Fire Door is Open and Closing 

Mechanism Disabled. 

Figure 79. Temperature Profiles for an Initial 

2000 kW Fire Source. Fire At Time = 54 s. 

Fire Door Open. 

Figure 80. Oxygen Concentrations for an 

Initial 2000 kW Fire Source. Fire At 

Time = 54 s. Fire Door is Open.
39

Figure 85. Temperature Profiles for an 

Initial 2000 kW Fire Source. Fire At Time 

= 166 s. Fire Door Open and Closing 

Mechanism Disabled. 

Figure 86. Oxygen Concentrations for an 

Initial 2000 kW Fire Source. Fire At 

Time = 166 s. Fire Door is Open and Closing 

Mechanism Disabled. 

Figure 87. Temperature Profiles for an 

Initial 2000 kW Fire Source. Fire At 

Time = 375 s. Fire Door Open and 

Closing Mechanism Disabled. 

Figure 88. Oxygen Concentrations for an 

Initial 2000 kW Fire Source. Fire At Time = 

375 s. Fire Door is Open and Closing 

Mechanism Disabled. 

Figure 89. Temperature Profiles for an 

Initial 2000 kW Fire Source. Fire At 

Time = 644 s. Fire Door Open and Closing 

Mechanism Disabled. 

Figure 90. Oxygen Concentrations for an Initial 

2000 kW Fire Source. Fire At Time = 644 s. 

Fire Door is Open and Closing Mechanism 

Disabled. 
40

The gas temperatures for the initial 500 kW fire source closed door cases, Figure 91 

(Centigrade Temperatures) and Figure 92 (Fahrenheit Temperatures) are plotted versus 

time. Peak temperatures were approximately 170 °C (338 °F). As the fire door closed at 

126 s and the fire consumed most of the oxygen in Unit 20, the gas temperatures near the 

closed fire door decreased. The gas temperatures for the 500 kW open door cases, Figure 

93 (Centigrade Temperatures) and Figure 94 (Fahrenheit Temperatures) are plotted versus 

time. Peak temperatures were slightly less than 170 °C (338 °F). As the rear door and 

basement windows were opened, the additional air and oxygen allowed the fire to grow and 

produced an increase in gas temperatures after 1300 s. 

 

The gas temperatures for the initial 1000 kW fire source closed door cases, Figure 95 

(Centigrade Temperatures) and Figure 96 (Fahrenheit Temperatures) are plotted versus 

time. Peak temperatures were approximately 240 °C (464 °F). As the fire door closed at 

81 s and the fire consumed most of the oxygen in Unit 20, the gas temperatures near the 

closed fire door decreased. The gas temperatures for the 1000 kW open door cases, Figure 

97 (Centigrade Temperatures) and Figure 98 (Fahrenheit Temperatures) are plotted versus 

time. Peak temperatures were significantly higher, 230 °C (446 °F) than in the closed door 

case. As the rear door and basement windows were opened, the additional air and oxygen 

allowed the fire to grow and produced a steep increase in gas temperatures after 1300 s 

than in the 500 kW fire case. 

The gas temperatures for the 2000 kW closed door cases, Figure 99 (Centigrade Temperatures) and Figure 100 (Fahrenheit Temperatures) are plotted versus time. Peak temperatures were approximately 340 °C (644 °F). As the fire door closed at 57 s and the fire 

consumed most of the oxygen in Unit 20, the gas temperatures near the closed fire door 

decreased. The gas temperatures for the 2000 kW open door cases, Figure 101 (Centigrade 

Temperatures) and Figure 102 (Fahrenheit Temperatures) are plotted versus time. Peak 

temperatures were similar, 359 °C (678 °F) to the closed door case. As the rear door and 

basement windows were opened, the additional air and oxygen allowed the fire to grow and 

produced a steep increase in gas temperatures after 1300 s than in the 500 kW or 1000 kW 

fire cases. 

Overall, this limited set of temperatures near the top of the fire door indicate that the higher 

heat release fires, especially the 2000 kW case, produced significantly higher gas 

temperatures than the lower heat release fires. The temperature peak was narrower for the 

closed door cases as compared to the broader peaks of the open door reconstructions. As 

the rear door in Unit 20 and the two windows in Unit 22 were opened after 1300 s, the 

gases temperatures increased in each of the open door cases. 

In the basements of Unit 20 and 22, as each fire grew, the oxygen concentration dropped 

below concentrations which would allow combustion to occur. FDS would not allow 

burning or combustion to occur in the cells where the oxygen concentration dropped to 

lower concentrations. Fire scenarios where the oxygen has decreased to a level 

insufficient to support burning are termed “ventilation limited”. Each of the fires in this 

study consumed sufficient oxygen to reduce the burning rate or become ventilation limited. 
41

0

50

100

150

200

250

300

350

400

0 200 400 600 800 1000 1200 1400 1600 1800 2000

 Gas Temperature, 

o

C

 (Top of Fire Door)

Time, s

Fusible Link Activation

 Temperature - 74o C

Door Closes

 at 126 s

Closed Door

Figure 91. Temperatures (Centigrade) versus Time for Combustion 

Gases Near the Fusible Link on the Fire Door. For a Fire with an 

Initial 500 kW Heat Release Rate, the Fire Door Closed at 126 s. 

0

100

200

300

400

500

600

700

800

0 200 400 600 800 1000 1200 1400 1600 1800 2000

 Gas Temperature, 

o

F

 (Top of Fire Door)

Time, s

Fusible Link Activation

 Temperature - 165o

 F

Door Closes

 at 126 s

Closed Door

Figure 92. Temperatures (Fahrenheit) versus Time for Combustion 

Gases Near the Fusible Link on the Fire Door. For a Fire with an Initial 

500 kW Heat Release Rate, the Fire Door Closed at 126 s. 
42

Figure 94. Temperatures (Fahrenheit) versus Time for Combustion Gases 

Near the Fusible Link on the Fire Door. For a Fire with an initial 500 kW Heat 

Release Rate, the Fire Door Closing Mechanism Was Disabled. 

Figure 93. Temperatures (Centigrade) versus Time for Combustion Gases 

Near the Fusible Link on the Fire Door. For a Fire with an Initial 500 kW Heat 

Release Rate, the Fire Door Closing Mechanism Was Disabled. 

0

50

100

150

200

250

300

350

400

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Gas Temperature , 

o

C

(Top of Fire Door)

Time, s

Fusible Link Activation

 Temperature - 74o C

 Window #1 on 

 Exposure 2

Vented at 1300 s

Window #2 on 

Exposure 2

Vented at 1600 s

Rear Door 

Forced 0.46 m

at 1310 s

Open Door

0

100

200

300

400

500

600

700

800

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Gas Temperature , 

o

F

(Top of Fire Door)

Time, s

Fusible Link Activation

 Temperature - 165o

 F

 Window #1 on 

 Exposure 2

Vented at 1300 s

Window #2 on 

Exposure 2

Vented at 1600 s

Rear Door 

Forced 0.46 m

at 1310 s

Open Door
43

Figure 95. Temperatures (Centigrade) versus Time for Combustion Gases 

Near the Fusible Link on the Fire Door. For a Fire with an initial 1000 kW 

Heat Release Rate, the Fire Door Closed at 81 s. 

Figure 96. Temperatures (Fahrenheit) versus Time for Combustion Gases 

Near the Fusible Link on the Fire Door. For a Fire with an Initial 1000 kW 

Heat Release Rate, the Fire Door Closed at 81 s.

0

50

100

150

200

250

300

350

400

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Gas Temperature, 

o

C

(Top of Fire Door)

Time, s

Fusible Link Activation

 Temperature - 74o

 C

Door Closes

 at 81 s

Closed Door

0

100

200

300

400

500

600

700

800

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Gas Temperature, 

o

F

(Top of Fire Door)

Time, s

Fusible Link Activation

 Temperature - 165o

 F

Door Closes

 at 81 s

Closed Door
44

Figure 98. Temperatures (Fahrenheit) versus Time for Combustion Gases Near 

the Fusible Link on the Fire Door. For a Fire with an Initial 1000 kW Heat 

Release Rate, the Fire Door Closing Mechanism Was Disabled. 

Figure 97. Temperatures (Centigrade) versus Time for Combustion Gases Near 

the Fusible Link on the Fire Door. For a Fire with an Initial 1000 kW Heat 

Release Rate, the Fire Door Closing Mechanism Was Disabled. 

0

50

100

150

200

250

300

350

400

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Gas Temperature, 

o

C

 (Top of Fire Door)

Time, s

Fusible Link Activation

 Temperature - 74o

 C

 Window #1 on 

 Exposure 2

Vented at 1300 s

Window #2 on 

Exposure 2

Vented at 1600 s

Rear Door 

Forced 0.46 m

at 1310 s

Open Door

0

100

200

300

400

500

600

700

800

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Gas Temperature, 

o

F

 (Top of Fire Door)

Time, s

Fusible Link Activation

 Temperature - 165o

 F

 Window #1 on 

 Exposure 2

Vented at 1300 s

Window #2 on 

Exposure 2

Vented at 1600 s

Rear Door 

Forced 0.46 m

at 1310 s

Open Door
45

Figure 99. Temperatures (Centigrade) versus Time for Combustion 

Gases Near the Fusible Link on the Fire Door. For a Fire with an 

Initial 2000 kW Heat Release Rate, the Fire Door Closed at 57 s. 

Figure 100. Temperatures (Fahrenheit) versus Time for Combustion 

Gases Near the Fusible Link on the Fire Door. For a Fire with an 

Initial 2000 kW Heat Release Rate, the Fire Door Closed at 57 s. 

0

50

100

150

200

250

300

350

400

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Gas Temperature , 

o

C

(Top of Fire Door)

Time, s

Fusible Link Activation

 Temperature - 74o

 C

Door Closes

 at 57 s Closed Door

0

100

200

300

400

500

600

700

800

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Gas Temperature , 

o

F

(Top of Fire Door)

Time, s

Fusible Link Activation

 Temperature - 165o

 F

Door Closes

 at 57 s Closed Door
46

Figure 102. Temperatures (Fahrenheit) versus Time for Combustion Gases 

Near the Fusible Link on the Fire Door. For a Fire with an Initial 2000 kW 

Heat Release Rate, the Fire Door Closing Mechanism Was Disabled. 

Figure 101. Temperatures (Centigrade) versus Time for Combustion Gases 

Near the Fusible Link on the Fire Door. For a Fire with an Initial 2000 kW 

Heat Release Rate, the Fire Door Closing Mechanism Was Disabled. 

0

50

100

150

200

250

300

350

400

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Gas Temperature, 

o

C

 (Top of Fire Door)

Time, s

Fusible Link Activation

 Temperature - 74o

 C

 Window #1 on 

 Exposure 2

Vented at 1300 s

Window #2 on 

Exposure 2

Vented at 1600 s

Rear Door 

Forced 0.46 m

at 1310 s

Open Door

0

100

200

300

400

500

600

700

800

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Gas Temperature, 

o

F

 (Top of Fire Door)

Time, s

Fusible Link Activation

 Temperature - 165o

 F

 Window #1 on 

 Exposure 2

Vented at 1300 s

Window #2 on 

Exposure 2

Vented at 1600 s

Rear Door 

Forced 0.46 m

at 1310 s

Open Door
47

In the closed door cases, the fires required 375 s, 204 s, and 130 s, to reduce the oxygen 

below 15 % for the 500 kW, 1000 kW, and 2000 kW heat release rates, respectively. In 

the open door cases where the fire had access to additional oxygen in Unit 22, the fires 

required 970 s, 550 s, and 310 s, to reduce the oxygen below 15 % for the 500 kW, 1000 

kW, and 2000 kW heat release rates, respectively. 

While each of the fires depleted the available oxygen, the unburned fuel remained in the 

basement of Unit 20 and 22. If additional oxygen were introduced into the basement, 

mixed with the remaining fuel, and found an ignition source, the fire would rekindle and 

begin to grow as long as it had sufficient fuel and oxygen. In the closed door cases where 

the fire door would have prevented flow from Unit 20 into Unit 22, the additional air may 

have entered through the lower portion of the rear door. Smoke and hot gases would have 

exited through the upper portion of the same rear door. The closed fire door would have 

prevented the movement of smoke or fresh air between Unit 20 and 22. If the fire door 

had closed in the actual fire, the unburned fuels and evaporating solvents may have lead to 

a fuel rich environment where there were high concentrations of fuel, but insufficient 

oxygen to allow combustion in Unit 20. The closed fire door and single door at the rear of 

the basement would not have been conducive for allowing additional air to flow into the 

basement of Unit 20. Sudden venting of Unit 20 could have led to a flammable mixture 

developing in Unit 20 even though the fire door was closed. If this mixture would have 

supported combustion and the mixture found an ignition source, the fuel/air mixture could 

have ignited within Unit 20. 

In the open door cases, the fire door remained open and air or smoke could flow through 

the fire door between Units 20 and 22. Similar to the closed door scenario, fresh air could 

have entered through the lower portion of the rear door and exited through the upper 

portion of the door. But, the basement windows which were opened on exposure #2 would 

have also provided a path for the smoke to exit while the fresh air was being drawn in 

through the rear door. The model simulations for the open door cases indicate that fresh 

air would probably have been drawn in through the rear door while hot smoke and 

combustion products were exiting the basement windows on exposure #2. In the actual 

fire, the unburned fuels and evaporating solvents may have lead to a fuel rich environment 

where there were high concentrations of fuel, but insufficient oxygen to allow combustion 

in Unit 20. However, as the air flowed in the rear door of Unit 20 and out the windows of 

Unit 22, the air would have probably entrained some of the unburned fuel and evaporated 

solvents as it passed through Unit 20. This mixture of fresh air and fuel would have 

flowed into the basement of Unit 22 which would have been less fuel rich since the 

solvents were in Unit 20. If the air/fuel flow into Unit 22 resulted in a flammable mixture 

that would have allowed combustion and the mixture found an ignition source, the fuel/air 

mixture could have ignited. 
48

8. Summary 

This limited set of Fire Dynamics Simulator reconstructions of the Astoria fire provides 

insight into the gas temperature and oxygen concentrations that may have existed in the 

basement of Unit 20 and Unit 22. The closed door recreations indicate that the fusible 

link would probably have seen high enough temperatures to allow the fire door to close in 

less than 130 s for fire sizes between 500 kW and 2000 kW. For comparison, these fire 

simulations also include scenarios where the fire door was not permitted to close. The 

closed door simulations demonstrate peak temperatures along the centerline of Unit 20 in 

excess of 480 °C (896 °F) for the 2000 kW fire. The open door reconstructions indicate 

peak temperatures along the centerline of Unit 20 in excess of 840 °C (1544 °F). The 

oxygen concentration profiles suggest that a 2000 kW fire with the fire door closed could 

have depleted the oxygen in Unit 20 in less than 380 s. A 2000 kW fire with the fire door 

open would have required more time, approximately 650 s, in order to deplete the oxygen 

in Unit 20 and 22. 

The reconstruction cases used a range of 500 kW, 1000 kW, and 2000 kW fires to explore 

the impact of different fire sizes. These simulations assume a specific fire size and do not 

consider the origin or cause of the fire. These simulations focused on the fire growth after 

ignition and up to the explosion, but did not include the explosion itself. If only 4% of the 

organic solvents that appear to have been stored in the basement became involved in the 

fire, then the heat release rate would have exceeded 500 kW. If 18 % of the hydrocarbon 

fuels had been consumed by the fire, the heat release rate is estimated to exceed 2000 kW. 

This range of heat release rates, from 500 kW to 2000 kW, does not include any of the 

other merchandise or combustibles that were located in the basement. 

9. Acknowledgements 

The authors would like to thank the Fire Department of New York and the Bureau of 

Alcohol Tobacco and Firearms (ATF) for their documentation of the structure involved in 

this fire incident. The authors would like to specifically extend their appreciation to Mr. 

Robert Byrnes of FDNY Special Operations Command and Mr. Gerald Haynes of ATF 

Fire Laboratory for their assistance in this reconstruction. The authors would also like to 

thank Mr. Richard Braddee of NIOSH’s Fire Fighter Fatality Investigation and Prevention 

Program for providing additional support for our fire reconstructions/line of duty death 

investigations. Finally we would like to thank Dr. Kevin McGrattan for his continued 

development of the NIST Fire Dynamics Simulator Model, and Dr. Glenn Forney for his 

continued development of SmokeView. 

10. References 

1. NIOSH Report “F2001-23 Hardware Store Explosion Claims the Lives of Three Career 

Fire Fighters- New York”, National Institute for Occupational Safety and Health, Cincinnati, OH, 

February 25, 2003, www.cdc.gov/niosh/firehome.html . 
49

2. Madrzykowski, D.; Vettori, R. L.; “Simulation of the Dynamics of the Fire at 3146 Cherry 

Road NE, Washington, DC, May 30, 1999”, National Institute of Standards and Technology, 

Gaithersburg, MD, NISTIR 6510, April 2000. 

3 . Madrzykowski, D.; Forney, G. P.; Walton, W. D.; “Simulation of the Dynamics of a Fire is 

a Two-Story Duplex, Iowa, December 22, 1999”, National Institute of Standards and Technology, 

Gaithersburg, MD NISTIR 6854, January 2002. 

4. Vettori, R.L.; Madrzykowski, D.; Walton, W.D.; “Simulation of the Dynamics of a Fire in 

a One-Story Restaurant – Texas, February 14, 2000”, National Institute of Standards and 

Technology, Gaithersburg, MD NISTIR 6923, October 2002. 

5. McGrattan, Kevin B.; Baum, Howard R.; Rehm, Ronald G.; Hamins, Anthony; Forney, 

Glenn P.; “Fire Dynamics Simulator – Technical Reference Guide”, National Institute of Standards 

and Technology, Gaithersburg, MD, NISTIR 6467, January 2000. 

6. McGrattan, Kevin B.; Hamins, Anthony; and Stroup, David; “Sprinkler, Smoke & Heat 

Vent, Draft Curtain Interaction – Large Scale Experiments and Model Development”, National 

Institute of Standards and Technology, Gaithersburg, MD, NISTIR 6196-1, September 1998. 

7. McGrattan, Kevin B.; Baum, Howard R.; Rehm, Ronald G.; “Large Eddy Simulations of 

Smoke Movement”, Fire Safety Journal, vol 30 (1998), p 161-178. 

8. McGrattan, Kevin B.; Forney, Glenn P.; “Fire Dynamics Simulator – User’s Manual”, 

National Institute of Standards and Technology, Gaithersburg, MD, NISTIR 6469, January 2000. 

9. Bunker, Merton, W.; Moore, Wayne, D.; “National Fire Alarm Code Handbook”, Third 

Edition, National Fire Protection Association, Quincy, MA, (1999), p 113-340. 

10. McGrattan, Kevin B.; Hamins, Anthony; Stroup, David; “Sprinkler, Smoke & Heat Vent, 

Draft Curtain Interaction—Large Scale Experiments and Model Development”, National Institute 

of Standards and Technology, Gaithersburg, MD, NISTIR 6196-1, September 1998.
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