NISTIR 6750 

Measurement Techniques for Low Heat Flux 

Exposures to Fire Fighters Protective Clothing 

Robert L. Vettori 

William H. Twilley 

David W. Stroup 
NISTIR 6750 

Measurement Techniques for Low Heat Flux 

Exposures to Fire Fighters Protective Clothing 

Robert L. Vettori 

William H. Twilley 

David W. Stroup 

Building and Fire Research Laboratory 

National Institute of Standards and Technology 

Gaithersburg, MD 20899-8641 

June 2001 

U.S. Department of Commerce 

Donald L. Evans, Secretary 

National Institute of Standards and Technology 

Karen H. Brown, Acting Director 
 iii 

Table of Contents 

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

List of Tables ................................................................................................................................. ix 

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

1.0 Introduction............................................................................................................................. 2 

2.0 Sensor Selection...................................................................................................................... 4 

3.0 Experimental Set Up............................................................................................................... 5 

4.0 Experimental Procedure and Data Acquisition....................................................................... 6 

5.0 Data Presentation .................................................................................................................... 7 

6.0 Results..................................................................................................................................... 8 

6.1 Temperature Measurement ................................................................................................. 8 

6.2 Heat Flux Measurement.................................................................................................... 10

7.0 Uncertainty Analysis............................................................................................................. 11 

8.0 Discussion............................................................................................................................. 12 

9.0 Conclusions........................................................................................................................... 16 

10.0 Acknowledgements............................................................................................................... 16 

11.0 References............................................................................................................................. 80 
 iv 

List of Figures 

Figure 1. Copper disk in the exposed position, no substrate. ...................................................... 27 

Figure 2. Copper disk in substrate. .............................................................................................. 27 

Figure 3. 12 thermocouples exposed. .......................................................................................... 28 

Figure 4. 12 thermocouples mounted on substrate. ..................................................................... 28 

Figure 5. Encapsulated type T (Copper versus Copper Nickel) thermocouple exposed. ............ 29 

Figure 6. Encapsulated type T (Copper versus Copper Nickel) thermocouple mounted in 

substrate. .................................................................................................................... 29 

Figure 7. Thin film sensor in the exposed position...................................................................... 30 

Figure 8. Test apparatus. This figure show the protective clothing set between the radiant 

panel and the sensor................................................................................................... 30 

Figure 9. Experimental set up for “Exposed” configuration. Drawing not to scale. .................. 31 

Figure 10. Experimental set up for “Substrate” configuration. Sensor is mounted in the 

substrate such that its surface is flush with the substrate surface. Drawing not to 

scale. .......................................................................................................................... 31 

Figure 11. Experimental set up for " Fabric-Exposed-No Space" configuration. Sensor is 

touching the back of the protective clothing. Drawing not to scale. ........................ 32 

Figure 12. Experimental set up for "Fabric-Exposed-Space" configuration. There is an air 

gap of 6mm (0.25 in) between the sensor and the protective clothing. Drawing 

not to scale. ................................................................................................................ 32

Figure 13. Experimental set up for "Fabric-Substrate-No Space" configuration. Sensor is 

mounted in substrate and surface of sensor and substrate are touching protective 

clothing. Drawing not to scale. ................................................................................. 33 

Figure 14. Experimental set up for "Fabric-Substrate-Space" configuration. Sensor is 

mounted in substrate and there is a 6 mm (0.25 in) air gap between the 

protective clothing and the sensor. Drawing not to scale. ........................................ 33 

Figure 15. Three layers that make up typical fire fighter protective clothing. ............................ 34 

Figure 16. Response of all type J thermocouples, exposed, 1.2 kW/m2

...................................... 34 

Figure 17. Response of all type J thermocouples, exposed, 5.0 kW/m2...................................... 35 

Figure 18. Response of all type K thermocouples, exposed, 1.2 kW/m2

..................................... 35 

Figure 19. Response of all type K thermocouples, exposed, 5.0 kW/m2..................................... 36 

Figure 20. Response of all type T thermocouples, exposed, 1.2 kW/m2. .................................... 36 

Figure 21. Response of all type T thermocouples, exposed, 5.0 kW/m2. .................................... 37 

Figure 22. Response of all type J thermocouples, substrate, 1.2 kW/m2..................................... 37 

Figure 23. Response of all type J thermocouples, substrate, 5.0 kW/m2

..................................... 38 

Figure 24. Response of all type K thermocouples, substrate, 1.2 kW/m2

.................................... 38 

Figure 25. Response of all type K thermocouples, substrate, 5.0 kW/m2

.................................... 39 

Figure 26. Response of all type T thermocouples, substrate, 1.2 kW/m2

.................................... 39 
 v 

Figure 27. Response of all type T thermocouples, substrate, 5.0 kW/m2

.................................... 40 

Figure 28. Response of all type J thermocouples, fabric-exposed-no space, 1.2 kW/m2. ........... 40 

Figure 29. Response of all type J thermocouples, fabric-exposed-no space 5.0 kW/m2

. ............ 41 

Figure 30. Response of all type K thermocouples, fabric-exposed-no space, 1.2 kW/m2........... 41 

Figure 31. Response of all type K thermocouples, fabric-exposed-no space, 5.0 kW/m2........... 42 

Figure 32. Response of all type T thermocouples, fabric-exposed-no space, 1.2 kW/m2. .......... 42 

Figure 33. Response of all type T thermocouples, fabric-exposed-no space, 5.0 kW/m2. .......... 43 

Figure 34. Response of all type J thermocouples, fabric-exposed-space, 1.2 kW/m2

. ................ 43 

Figure 35. Response of all type J thermocouples, fabric-exposed-space, 5.0 kW/m2. ................ 44 

Figure 36. Response of all type K thermocouples, fabric-exposed-space, 1.2 kW/m2................ 44 

Figure 37. Response of all type K thermocouples, fabric-exposed-space, 5.0 kW/m2................ 45 

Figure 38. Response of all type T thermocouples, fabric-exposed-space, 1.2 kW/m2. ............... 45 

Figure 39. Response of all type T thermocouples, fabric-exposed-space, 5.0 kW/m2

. ............... 46 

Figure 40. Response of all type J thermocouples, fabric-substrate-no space, 1.2 kW/m2

........... 46 

Figure 41. Response of 0.13 mm, 0.26 mm, and 0.51 mm type J thermocouples, fabricsubstrate-no space, 5.0 kW/m2

. No data for 0.81 mm type J thermocouple............. 47 

Figure 42. Response of all type K thermocouples, fabric-substrate-no space, 1.2 kW/m2

.......... 47 

Figure 43. Response of all type K thermocouples, fabric-substrate-no space, 5.0 kW/m2.......... 48 

Figure 44. Response of all type T thermocouples, fabric-substrate-no space, 1.2 kW/m2

. ......... 48 

Figure 45. Response of all type T thermocouples, fabric-substrate-no space, 5.0 kW/m2. ......... 49 

Figure 46. Response of all type J thermocouples, fabric-substrate-space, 1.2 kW/m2................ 49 

Figure 47. Response of 0.13 mm, 0.26 mm, and 0.51 mm type J thermocouples, fabricsubstrate-space, 5.0 kW/m2

. No data for 0.81 mm type J thermocouple.................. 50 

Figure 48. Response of all type K thermocouples, fabric-substrate-space, 1.2 kW/m2

............... 50 

Figure 49. Response of all type K thermocouples, fabric-substrate-space, 5.0 kW/m2............... 51 

Figure 50. Response of all type T thermocouples, fabric-substrate-space, 1.2 kW/m2. .............. 51 

Figure 51. Response of all type T thermocouples, fabric-substrate-space, 5.0 kW/m2

. .............. 52 

Figure 52. Response of type J, K, and T thermocouples, 0.13 mm wire diameter, exposed, 

1.2 kW/m2

.................................................................................................................. 52 

Figure 53. Response of type J, K, and T thermocouples, 0.13 mm wire diameter, exposed, 

5.0 kW/m2

.................................................................................................................. 53 

Figure 54. Response of type J, K, and T thermocouples, 0.81 mm wire diameter, exposed, 

1.2 kW/m2.................................................................................................................. 53 

Figure 55. Response of type J, K, and T thermocouples, 0.81 mm wire diameter, exposed, 

5.0 kW/m2.................................................................................................................. 54 

Figure 56. Response of type J, K, and T thermocouples, 0.13 mm wire diameter, substrate, 

1.2 kW/m2.................................................................................................................. 54 

Figure 57. Response of type J, K, and T thermocouples, 0.13 mm wire diameter, substrate, 

5.0 kW/m2.................................................................................................................. 55 
 vi 

Figure 58. Response of type J, K, and T thermocouples, 0.81 mm wire diameter, substrate, 

1.2 kW/m2

.................................................................................................................. 55 

Figure 59. Response of type J, K, and T thermocouples, 0.81 mm wire diameter, substrate 

5.0 kW/m2

.................................................................................................................. 56 

Figure 60. Response of type J, K, and T thermocouples, 0.13 mm wire diameter, fabricexposed-no space, 1.2 kW/m2

.................................................................................... 56 

Figure 61. Response of type J, K, and T thermocouples, 0.13 mm wire diameter, fabricexposed-no space, 5.0 kW/m2

.................................................................................... 57 

Figure 62. Response of type J, K, and T thermocouples, 0.81 mm wire diameter, fabricexposed-no space, 1.2 kW/m2

.................................................................................... 57 

Figure 63. Response of type J, K, and T thermocouples, 0.81 mm wire diameter, fabricexposed-no space, 5.0 kW/m2

.................................................................................... 58 

Figure 64. Response of type J, K, and T thermocouples, 0.13 mm wire diameter, fabricexposed-space, 1.2 kW/m2

......................................................................................... 58 

Figure 65. Response of type J, K, and T thermocouples, 0.13 mm wire diameter, fabricexposed-space, 5.0 kW/m2

......................................................................................... 59 

Figure 66. Response of type J, K, and T thermocouples, 0.81 mm wire diameter, fabricexposed-space, 1.2 kW/m2

......................................................................................... 59 

Figure 67. Response of type J, K, and T thermocouples, 0.81 mm wire diameter, fabricexposed-space, 5.0 kW/m2

......................................................................................... 60 

Figure 68. Response of type J, K, and T thermocouples, 0.13 mm wire diameter, fabricsubstrate-no space, 1,25 kW/m2

................................................................................. 60 

Figure 69. Response of type J, K, and T thermocouples, 0.13 mm wire diameter, fabricsubstrate-no space, 5.0 kW/m2

................................................................................... 61 

Figure 70. Response of type J, K, and T thermocouples, 0.81 mm wire diameter, fabricsubstrate-no space, 1.2 kW/m2

................................................................................... 61 

Figure 71. Response of type K, and T thermocouples, 0.81 mm wire diameter, fabricsubstrate-no space, 5.0 kW/m2

. No data for type J thermocouple............................ 62 

Figure 72. Response of type J, K, and T thermocouples, 0.13 mm wire diameter, fabricsubstrate-space, 1.2 kW/m2

........................................................................................ 62 

Figure 73. Response of type J, K, and T thermocouples, 0.13 mm wire diameter, fabricsubstrate-space, 5.0 kW/m2

........................................................................................ 63 

Figure 74. Response of type J, K, and T thermocouples, 0.81 mm wire diameter, fabricsubstrate-space, 1.2 kW/m2

........................................................................................ 63 

Figure 75. Response of type K, and T thermocouples, 0.81 mm wire diameter, fabricsubstrate-space, 5.0 kW/m2

. No data for type J thermocouple................................. 64 

Figure 76. Response of encapsulated type T thermocouple, exposed, all three heat flux 

levels, with error bars. ............................................................................................... 64 

Figure 77. Response of encapsulated type T thermocouple, substrate, all three heat flux 

levels, with error bars. ............................................................................................... 65 

Figure 78. Response of encapsulated type T thermocouple, fabric-exposed-no space, all 

three heat flux levels, with error bars. ....................................................................... 65 
 vii 

Figure 79. Response of encapsulated type T thermocouple, fabric-exposed-space, all three 

heat flux levels, with error bars. ................................................................................ 66 

Figure 80. Response of encapsulated type T thermocouple, fabric-substrate-no space, all 

three heat flux levels, with error bars. ....................................................................... 66 

Figure 81. Response of encapsulated type T thermocouple, fabric-substrate-space, all three 

heat flux levels, with error bars. ................................................................................ 67 

Figure 82. Response of copper disk with 4 type J thermocouples, exposed, all three heat 

flux levels, with error bars......................................................................................... 67 

Figure 83. Response of copper disk with 4 type J thermocouples, substrate, all three heat 

flux levels, with error bars......................................................................................... 68 

Figure 84. Response of copper disk with 4 type J thermocouples, fabric-exposed-no space, 

all three heat flux levels, with error bars. .................................................................. 68 

Figure 85. Response of copper disk with 4 type J thermocouples, fabric-exposed-space, all 

three heat flux levels, with error bars. ....................................................................... 69 

Figure 86. Response of copper disk with 4 type J thermocouples, fabric-substrate-no space, 

all three heat flux levels, with error bars. .................................................................. 69 

Figure 87. Response of copper disk with 4 type J thermocouples, fabric-substrate-space, all 

three heat flux levels, with error bars. ....................................................................... 70 

Figure 88. Response of copper disk with 1 type J thermocouple, exposed, all three heat flux 

levels, with error bars. ............................................................................................... 70 

Figure 89. Response of copper disk with 1 type J thermocouple, substrate, all three heat flux 

levels, with error bars. ............................................................................................... 71 

Figure 90. Response of thin film heat flux gauge, exposed, all three heat flux levels, with 

error bars.................................................................................................................... 71 

Figure 91. Response of thin film heat flux gauge, substrate, all three heat flux levels, with 

error bars.................................................................................................................... 72 

Figure 92. Response of thin film heat flux gauge, fabric-exposed-no space, all three heat 

flux levels, with error bars......................................................................................... 72 

Figure 93. Response of thin film heat flux gauge, fabric-exposed-space, all three heat flux 

levels, with error bars. ............................................................................................... 73 

Figure 94. Response of thin film heat flux gauge, fabric-substrate-no space, all three heat 

flux levels, with error bars......................................................................................... 73 

Figure 95. Response of thin film heat flux gauge, fabric-substrate-space, all three heat flux 

levels, with error bars. ............................................................................................... 74 

Figure 96. Response of Schmidt-Boelter total heat flux gauge, exposed, all three heat flux 

levels, with error bars. ............................................................................................... 74 

Figure 97. Response of Schmidt-Boelter total heat flux gauge, fabric-exposed-no space- two 

heat flux levels, with error bars. ................................................................................ 75 

Figure 98. Response of Schmidt-Boelter total heat flux gauge, fabric-exposed-space, two 

heat flux levels, with error bars. ................................................................................ 75 

Figure 99. Response of Schmidt-Boelter total heat flux gauge, fabric-substrate-no space, 

two heat flux levels, with error bars. ......................................................................... 76 
 viii 

Figure 100. Response of Schmidt-Boelter total heat flux gauge, fabric-substrate-space, two 

heat flux levels, with error bars. ................................................................................ 76 

Figure 101. Response of sapphire window radiometer, exposed, all three heat flux levels, 

with error bars............................................................................................................ 77 

Figure 102. Response of sapphire window radiometer, fabric-exposed-no space, two heat 

flux levels, with error bars......................................................................................... 77 

Figure 103. Response of sapphire window radiometer, fabric-exposed-space, two heat flux 

levels, with error bars. ............................................................................................... 78 

Figure 104. Response of sapphire window radiometer, fabric-substrate-no space, two heat 

flux levels, with error bars......................................................................................... 78 

Figure 105. Response of sapphire window radiometer, fabric-substrate-space, two heat flux 

levels, with error bars. ............................................................................................... 79 

Figure 106. Response of zinc selenide window radiometer, exposed, all three heat flux 

levels with error bars. ................................................................................................ 79 
 ix 

List of Tables 

Table 1. Description of sensors.................................................................................................... 17 

Table 2. Experimental Configurations......................................................................................... 18 

Table 3. Thermal properties of “Bakelite” substrate material ..................................................... 18 

Table 4. Thermal properties of protective clothing ..................................................................... 19 

Table 5. Thermal conductivity of thermocouple materials.......................................................... 19 

Table 6. Measurement uncertainties of sensors ........................................................................... 19 

Table 7. Response of 0.13 mm (0.005 in) type J thermocouple after 10 min exposure. ............. 20 

Table 8. Response of 0.26 mm (0.010 in) type J thermocouple after 10 min exposure. ............. 20 

Table 9. Response of 0.51 mm (0.020 in) type J thermocouple after 10 min exposure. ............. 20 

Table 10. Response of 0.81 mm (0.032 in) type J thermocouple after 10 min exposure. ........... 21 

Table 11. Response of 0.13 mm (0.005 in) type K thermocouple after 10 min exposure........... 21 

Table 12. Response of 0.26 mm (0.010 in) type K thermocouple after 10 min exposure........... 21 

Table 13. Response of 0.51 mm (0.020 in) type K thermocouple after 10 min exposure........... 22 

Table 14. Response of 0.81 mm (0.032 in) type K thermocouple after 10 min exposure........... 22 

Table 15. Response of 0.13 mm (0.005 in) type T thermocouple after 10 min exposure. .......... 22 

Table 16. Response of 0.26 mm (0.010 in) type T thermocouple after 10 min exposure. .......... 23 

Table 17. Response of 0.51 mm (0.020 in) type T thermocouple after 10 min exposure. .......... 23 

Table 18. Response of 0.81 mm (0.032 in) type T thermocouple after 10 min exposure. .......... 23 

Table 19. Response of encapsulated thermocouple after 10 min exposure. ................................ 24 

Table 20. Response of copper disk with one thermocouple attached after 10 min exposure...... 24 

Table 21. Response of copper disk with four thermocouples attached after 10 min exposure.... 24 

Table 22. Response of thin film heat flux sensor after 10 min exposure..................................... 25 

Table 23. Response of Sapphire window radiometer after 10 min exposure. ............................. 25 

Table 24. Response of Schmidt-Boelter Total Heat Flux Gauge after 10 min exposure............. 25 

Table 25. Response of Zinc Selenide radiometer after 10 min exposure. ................................... 26 
 1 

Measurement Techniques for Low Heat Flux Exposures to Fire Fighters 

Protective Clothing 

Robert L. Vettori 

William H. Twilley 

David W. Stroup 

Abstract 

A series of experiments were conducted to investigate measurement technologies that are 

necessary and appropriate for evaluating the thermal performance of fire fighter protective 

clothing under low heat flux (≤5.0 kW/m2) exposure conditions and for relatively long periods of 

time, up to 10 min. The 19 sensors were tested in six different configurations and exposed to 

three different levels of heat flux from a natural-gas fired radiant panel. The 6 different 

configurations were; (1) the sensor exposed to the radiant panel with no contact with anything 

other than the wires transmitting the sensor output signal, (2) the sensor mounted on a substrate 

such that the surface of the sensor is flush with the surface of the substrate and exposed to the 

radiant panel, (3) a section of fire fighter protective clothing is placed between the sensor and the 

radiant panel, the sensor is touching the back of the material, (4) a section of fire fighter 

protective clothing is placed between the sensor and the radiant panel, the sensor is placed 6 mm 

(0.25 in) behind the material, (5) a section of fire fighter protective clothing is placed between 

the sensor and the radiant panel, the sensor is mounted on the substrate and touching the back of 

the material, (6) a section of fire fighter protective clothing is placed between the sensor and the 

radiant panel, the sensor is mounted on the substrate and placed 6 mm (0.25 in) behind the 

material. The three levels of heat flux were 1.2 kW/m2

, 2.5 kW/m2, and 5.0 kW/m2. For a given 

configuration, there was a significant difference in the recorded measurement of heat flux and 

temperature. All sensors were affected by mounting them on the substrate. Based on the results 

from this experimental series the Schmidt-Boelter total heat flux gauge was deemed the most 

appropriate for measuring incident heat flux. For measuring the surface temperature of a fabric, 

the use of a thermal pad, made of a material with a high thermal conductivity to which is 

attached a thermocouple with lead wires made of a material with a low thermal conductivity, 

may be the most appropriate. 

Keywords: burns, fire fighters, fire research, heat flux, protective clothing, sensors, 

temperature measuring instruments, temperature measurements, test methods 
 2 

The National Institute of Occupational Safety and Health (NIOSH) has been given the task of 

addressing the national problem of increasing occupational fire fighter injuries and fatalities. 

The objectives of the NIOSH program are: to define the magnitude and characteristics of workrelated deaths and severe injuries among fire fighters, to develop recommendations for the 

prevention of these injuries and deaths, and to implement and disseminate prevention efforts. In 

an effort to prevent burn injuries NIOSH has identified the need to understand the thermal 

performance of fire fighter protective clothing under relatively low heat flux exposures, 

≤ 5 kW/m2

 with extended exposure times of up to 10 min. Currently, there are no standardized 

test or measurement protocols that adequately address the performance of fire fighter protective 

clothing under these conditions. 

 

Many workers are exposed to fire hazards in a variety of industrial settings. This is especially 

true for fire fighters that are exposed to many different thermal environments including flashover 

conditions. The protective clothing worn by fire fighters is designed to give them a degree of 

protection from the thermal environment produced by a fire. It allows fire fighters to work 

where they would be otherwise unable to survive. Fire fighters are at great risk in these 

environments and protective clothing worn by fire fighters has limitations in terms of thermal 

protection. The National Fire Protection Association (NFPA) 1971 Standard on Protective 

Ensemble for Structural Fire Fighting [1] gives minimum requirements for thermal insulation of 

protective clothing. While the thermal performance of fire fighter’s protective clothing has been 

a point of interest and discussion for the last several decades, little scientific information is 

available on the technical issues. Much of the data is empirical or based on fire service field 

experience. Although an excellent source of qualitative data, field experience does not provide 

the necessary understanding of how to improve the performance of protective clothing. There is 

still a lack of quantitative data on thermal performance of fire fighter protective clothing. Very 

little research has been conducted to develop methods for predicting the thermal performance of 

protective clothing throughout the range of environments faced by a fire fighter. However, much 

data has been collected in an effort to characterize the thermal environments experienced by fire 

fighters [2,3,4]. The conditions ranged from pre and post flashover fires within burning 

structures to conditions on the fire ground outside of burning structures. Foster and Roberts [3] 

divided this thermal environment into four categories with the associated heat flux exposures that 

a fire fighter would experience as follows: routine up to 1 kW/m2

, hazardous from 1 kW/m2 to 4 

kW/m2, extreme 4 kW/m2 to 10 kW/m2, and critical over 10 kW/m2. Abbott [4], in turn, divides 

the thermal environment into three categories: routine, ordinary, and emergency. The associated 

heat fluxes associated with these divisions are: routine up to 1.7 kW/m2

, ordinary 1.7 kW/m2 to 

12.5 kW/m2, and emergency greater than 12.5 kW/m2. While both Foster et. al. and Abbott 

considered an exposure to a heat flux of 5 kW/m2

 as hazardous, it is considerably less than the 

Thermal Protective Performance Test exposure of 84 kW/m2 described in NFPA 1971. 

In order to predict the extent of injury to a human that would result in a heat exposure it is 

necessary to know the temperature history of the skin’s basal layer. Many investigators have 

examined skin burning and developed criteria to predict the onset of irreversible damage [5,6]. 

1.0 Introduction 
 3 

For damage to occur the growing or basal layer temperature must reach 44 °C (112 °F). At this 

temperature, irreversible damage begins to occur to the basal layer and the longer it is at or above 

this temperature the greater the amount of damage. 

For the temperature at the surface of the skin or a portion within it to be predicted, the heat 

transfer to the surface of the skin needs to be known. Once the heat transfer and its variation 

with location and times is known, a heat transfer model of human skin can be used to estimate 

the damage due to burning. Heat transfer from a heat source into the surface of the skin can be 

modeled as transient heat transfer into a semi-infinite solid [7,8]. For the case of a constant heat 

flux at the surface and constant thermal physical properties, the analytical solution can be shown 

to be: 

( ) 













′′  −













 − 



 





′′

− = t

x erfc k

q x

t

x

k

t

q

T x t T o

o

i

α α

π

α

4 2

exp

2

,

2

2

1

Equation 1 

Where T = temperature K

 Ti = initial temperature K

 o q′′ = incident heat flux 2 m

W

 α = thermal diffusivity 



 





c

k

ρ s

m

2

 ρ = density 3

m

kg

 c = specific heat kgK

J

 t = time s

 k = thermal conductivity mK

W

 x = distance into solid m

 erfc = complimentary error function 

At the surface, i.e. x = 0 this reduces to 

( ) k c

q t T t Ti

π ρ

2 0, − =

Equation 2 
 4 

Physiological burn damage rate models are based on knowledge of the intensity and duration of 

incident heat flux on the skin surface. The purpose of a sensor is either to obtain a direct reading 

of the heat flux or to permit the heat flux to be predicted. 

The objective of this experimental series is to examine the response of various thermal sensors1

, 

in different configurations, exposed to relatively low heat fluxes, ≤ 5 kW/m2, for a period of 10 

min. It will demonstrate that sensors made of various materials, placed in identical 

configurations and exposed to the same radiant heat flux will give different results. Also, that 

sensors made of the same material, placed in identical configurations and exposed to the same 

radiant heat flux will report different results based on the size of the sensor and lead wires that 

carry the sensor signal. Most of the sensors examined in this experimental series have been used 

in past research in a variety of configurations to measure the heat transfer through protective 

clothing. 

The sensors chosen for this experimental series are listed in Table 1. 

The copper disk sensor, Figure 1 and Figure 2, is presently used to measure the applied heat flux 

in the Thermal Protective Performance (TPP) Test as described in NFPA 1971. Type J 

thermocouples, such as those shown in Figure 3 and Figure 4, are used to measure the 

temperature rise of the copper disk used in the TPP test. The encapsulated thermocouple, Figure 

5 and Figure 6, is one type of sensor that is presently used in full-scale experiments utilizing 

mannequins [9]. The encapsulated thermocouple used in these experiments consisted of a type T 

thermocouple buried below the exposed surface of a cast resin plug. Type K thermocouples, 

Figure 3 and Figure 4, and the water cooled Schmidt-Boelter total heat flux gauge have both 

been used for many years in fire research to measure temperatures and heat fluxes respectively 

[10]. For each type of thermocouple, four different wire sizes were tested. Only one 

encapsulated thermocouple was tested. The thin film heat flux sensor, Figure 7, like the watercooled Schmidt-Boelter total heat flux gauge measures the incident heat flux at its surface. The 

thin film sensor measurement is obtained from a thermopile heat flux sensor that occupies most 

of the surface area on the sensor face. Two water-cooled radiometers were also chosen. Both 

are based on the Schmidt-Boelter principle of measuring heat flux. Radiometers are designed to 

measure only the radiative fraction of thermal energy. If radiation and convection are both 

present, the radiometer will only monitor the radiative component. Radiometers typically 

employ a window or lens placed between the heat source and the heat flux sensor. The window 

or lens can be fabricated in such a way as to allow radiation of specific wavelength to pass 

through. In the case of these two radiometers, one had a sapphire lens which had a spectral 

transmittance of 0.15 μm to 5.0 μm and one with a zinc selenide window, which had a spectral 

transmittance of 0.5 μm to 22 μm. 

 

1

 Certain commercial equipment, instruments, or materials are identified in this paper in order to adequately specify 

the experimental procedure. Such identification does not imply recommendation or endorsement by the National 

Institute of Standards and Technology, nor does it imply that the materials or equipment identified are necessarily 

the best available for the purpose. 

2.0 Sensor Selection 
 5 

The test apparatus and its components are the same as the apparatus used in reference 11 and is 

shown in Figure 8. Radiant heat energy for this test is produced by a premixed air natural gas 

fueled radiant panel with a radiating surface measuring 305 mm by 457 mm (12 in by 18 in). 

The radiant panel type is specified in ASTM E162, Standard Test Method for Surface 

Flammability of Materials using a Radiant Heat Energy Source [12]. This radiant panel is 

normally operated at an average surface blackbody temperature of 943 K with variation not to 

exceed ± 4 K. 

A calibrated Schmidt-Boelter total heat flux gauge of the type specified in ASTM E1321, 

Standard Test Method for Determining Material Ignition and Flame Spread Properties [13] was 

used to measure the heat flux level. This water-cooled, thermopile, heat flux transducer has a 

nominal range of 0 kW/m2

 to 10 kW/m2 with a corresponding voltage range of 0 mV to 9 mV. 

The time constant to reach 63 % of final value for this heat flux gauge is not more than 290 ms 

with a corresponding time to reach 95 % of the final output of not more than 1 s. 

Since the radiant panel is always operated at a constant temperature, the incident heat flux is 

adjusted to the desired value by moving a trolley assembly that is attached to the radiant heat 

panel test frame. The sensor is attached to this moveable assembly. The distance from the 

radiant panel needed for each of the three desired heat fluxes was determined by the use of the 

Schmidt-Boelter total heat flux gauge and analytical methods. The energy incident on a surface 

a distance from a specific radiator, such as a radiant panel, may be found by use of the following: 

4

qo

′′ = φεσT

Equation 3 

Where o q′′ = incident heat flux 2

m

W

 φ = configuration factor 

 ε = emissivity of sensor surface 

 σ = Stefan Boltzmann constant (5.67 x 10 -8

2 4

m K

W ) 

 T = temperature of the radiant panel K

The emissivity of the Schmidt-Boelter total heat flux gauge is 0.96. The temperature of the 

radiant panel is 943 K ± 4 K. The configuration factor is used to take into account the 

geometrical relationship between the radiator, in this case the radiant panel, and the receiving 

element. It may be defined as the ratio of the intensity at the receiving element to the intensity of 

the radiator and is a function of the size of the radiating surface, its distance from the receiving 

element, and the relative orientation of the receiving element and radiator. For example, the 

distance from the radiant panel that would produce incident radiation of 2.5 kW/m2

 was 

determined by the use of the Schmidt-Boelter gauge as 0.85 m (33.5 in). By use of Equation 3, 

a configuration factor obtained from McGuire (14), and the range of temperatures for the radiant 

3.0 Experimental Set Up 
 6 

panel, the calculated incident heat flux at 0.85 m (33.5 in) from the radiant panel is in the range 

of 2.43 kW/m2

 to 2.52 kW/m2. 

Each sensor was tested in six different configurations. For each configuration, 10 experiments 

were conducted. The six different configurations are listed in Table 2 

The first configuration, “exposed,” Figure 9, was chosen to measure the response of each sensor 

when exposed to a radiant heat source. The second configuration, “substrate,” Figure 10, was 

chosen to measure the response of each sensor when mounted on a substrate and exposed to a 

radiant heat source. The material used for the substrate was bakelite with dimensions of 100 mm 

by 100 mm by 13 mm (4 in by 4 in by 0.5 in). The thermal properties of the substrate are given 

in Table 3. This was done to simulate the placement of the sensor on a skin simulant or on a 

mannequin to determine what effect this placement has on the sensor response. The third 

configuration, “fabric-exposed-no space,” Figure 11, measures the response of the sensor when 

placed behind protective clothing. This simulates the measurement of the heat transfer through 

protective clothing with the protective clothing touching the wearer’s skin. The fourth 

configuration, “fabric-exposed-space,” Figure 12, adds a space of approximately 6 mm (0.25 in) 

between the sensor and the protective clothing to simulate an air gap between the wearer and the 

protective clothing. The fifth configuration, “fabric-substrate-no space,” Figure 13, again places 

the sensor on a substrate, to simulate the sensor placed on a skin simulant or mannequin to 

determine the impact this placement has on the sensor response. The sixth and last 

configuration, “fabric-substrate-space,” Figure 14, is the same as the fifth configuration with a 

space of 6 mm (0.25 in) added between the sensors and the protective clothing to simulate an air 

gap between the wearer and the protective clothing. 

The piece of protective clothing placed between the sensor and radiant panel was made of 

materials used in the construction of typical fire fighter protective clothing. The individual 

components, an outer shell, a breathable moisture barrier, and a thermal liner, are shown in 

Figure 15 before assembly into a test specimen. The surface dimensions of the protective 

clothing were 305 mm by 355 mm (12 in by 14 in) with the 355 mm (14 in) dimension in the 

vertical direction. For all the experiments conducted in this series, there was no air gap between 

the individual components. Figure 8 shows an experimental set up in which the protective 

clothing assembly is placed between the radiant panel and the sensor. Thermal properties of the 

individual components that make up the protective clothing are listed in Table 4 and came from 

reference 18. The specific heats of these components are not available at this time. 

The gas fired radiant panel was ignited and allowed to preheat for 45 min. This preheat period 

allowed the radiant panel’s temperature to stabilize before calibration was attempted. Using the 

Schmidt-Boelter total heat flux transducer, the moveable assembly was positioned such that the 

incident heat flux was one of the three pre-determined levels. A thermal radiation shield which 

included a water cooled panel was placed between the assembly and the radiant panel. The 

sensor(s) was mounted on the assembly. The data acquisition system was started. After 60 s of 

background data the radiation shield was removed exposing the sensor(s) to the radiant panel. 

4.0 Experimental Procedure and Data Acquisition 
 7 

After a 10 min exposure the radiation shield was put back into place, the sensor(s) allowed to 

cool to ambient temperature and the experiment repeated. A computer controlled data logger 

recorded data at one second intervals. 

Data from the experiments are presented in two formats, tabular and graphical. First, a tabular 

format in which the final temperature increase or heat flux is given after a 10 min exposure along 

with plus and minus two standard deviations. Table 7 through Table 25 gives this information 

for each sensor in each of the six tested configurations. The first column of each table lists the 

six experimental configurations. The second, third, and fourth columns are the reported sensor 

response for the 1.2 kW/m2

, 2.5 kW/m2 and 5.0 kW/m2 exposures, respectively. The graphical 

format presents the sensor response curves versus time for the entire 10 min exposure. Each 

graph has multiple curves. These curves represent the response of more than one sensor to an 

exposure or the response of one sensor to all three heat flux exposures. At a minimum, the 

curves represent the average response of the sensor(s) for the 10 experiments. Many of the 

graphs have error bars that represent plus and minus two standard deviations. The caption for 

each figure will indicate the sensor or sensors reported, the configuration the sensor(s) was in, 

the heat flux exposure, and if the figure contains error bars. If possible, labels were placed on 

the graph indicating which sensor each curve represents. Often the sensor responses were so 

close together that labeling the curves was difficult. In this case the labels were omitted. For 

comparison purposes the figures can be divided into the following categories: 

Figure 16 through Figure 21 Response of one type of thermocouple to an exposure 

based on all four wire sizes in the “exposed” configuration. 

Figure 22 through Figure 27 Response of one type of thermocouple to an exposure 

based on all four wire sizes in the “substrate” configuration. 

Figure 28 through Figure 33 Response of one type of thermocouple to an exposure 

based on all four wire sizes in the “fabric-exposed-no 

space” configuration. 

Figure 34 through Figure 39 Response of one type of thermocouple to an exposure 

based on all four wire sizes in the “fabric-exposed-space” 

configuration. 

Figure 40 through Figure 45 Response of one type of thermocouple to an exposure 

based on all four wire sizes in the “fabric-substrate-no 

space” configuration. 

Figure 46 through Figure 51 Response of one type of thermocouple to an exposure 

based on all four wire sizes in the “fabric-substrate-space” 

configuration. 

Figure 52 through Figure 55 Response of all three thermocouple types to an exposure 

based on one wire size in the “exposed” configuration. 

Figure 56 through Figure 59 Response of all three thermocouple types to an exposure 

based on one wire size in the “substrate” configuration. 

5.0 Data Presentation 
 8 

Figure 60 through Figure 63 Response of all three thermocouple types to an exposure 

based on one wire size in the “fabric-exposed-no space” 

configuration. 

Figure 64 through Figure 67 Response of all three thermocouple types to an exposure 

based on one wire size in the “fabric-exposed-space” 

configuration. 

Figure 68 through Figure 71 Response of all three thermocouple types to an exposure 

based on one wire size in the “fabric-substrate-no space” 

configuration. 

Figure 72 through Figure 75 Response of all three thermocouple types to an exposure 

based on one wire size in the “fabric-substrate-space” 

configuration. 

Figure 76 through Figure 81 Response of encapsulated type T thermocouple. 

Figure 82 through Figure 89 Response of copper disks. 

Figure 90 through Figure 95 Response of thin film heat flux gauge. 

Figure 96 through Figure 100 Response of water-cooled Schmidt-Boelter total heat flux 

gauge. 

Figure 101 through Figure 105 Response of water-cooled sapphire window radiometer. 

Figure 106 Response of water-cooled zinc selenide window 

radiometer. 

6.1 Temperature Measurement 

Final Temperature Increases 

The sensor configuration, thermal properties of the sensor itself, and the incident radiant flux all 

affected the final temperature increases. Sensors in the “substrate” configuration recorded higher 

temperature increases than in the “exposed” configuration. Once the sensors were placed behind 

the protective clothing the effect of mounting the sensors on the substrate was not as significant. 

In these configurations, several sensors recorded less of a temperature increase when placed on 

the substrate. The size and the thermal conductivity of the thermocouple wire influenced the 

temperature increases reported by the twelve thermocouple sensors. Both copper disks, and the 

encapsulated thermocouple monitored greater temperature increases than the twelve 

thermocouple sensors. As would be expected, the 5.0 kW/m2

 value of incident flux produced 

significantly higher temperature increases than did the 2.5 kW/m2 or 1.2 kW/m2

 incident fluxes. 

Thermocouples 

All thermocouples recorded higher temperatures when in the “substrate” configuration then 

when in the “exposed” configuration. For the twelve thermocouples, the final temperature 

increases in the “exposed” configuration ranged from 1.6 °C to 2.7 °C (3 °F to 5 °F) at 

1.2 kW/m2

 to 1.1 °C to 9.0 °C (2 °F to 16 °F) at 5.0 kW/m2. When the thermocouples were 

6.0 Results 
 9 

placed in the “substrate” configuration the temperature increases ranged from 18.6 °C to 31.3 °C 

(33 °F to 56 °F) at 1.2 kW/m2

 to 68.0 °C to 112.0 °C (122 °F to 202 °F) at 5.0 kW/m2. When 

placed behind the protective clothing and having a space of 6 mm (0.25 in) between the sensor 

and the protective clothing, all 12 thermocouples again recorded higher temperature increases 

when placed on the substrate. However, when there is no space between the sensor and the 

protective clothing the effect of mounting the sensor on a substrate is not as clear. In the case of 

the thermocouples some recorded greater temperature increases when placed on the substrate and 

others less of a temperature increase when placed on the substrate. 

The thermal conductivity, emissivity, and diameter of the thermocouple wire did appear to 

impact the increase in temperatures reported by the type J, K, and T thermocouple sensor 

packages. The effect of thermal conductivity is most readily seen in the temperature increases or 

actually the reduced temperature increases of the type T thermocouples in the "substrate" 

configuration as compared to the type J and K thermocouples in the "substrate" configuration. 

For the 0.81 mm (0.032 in) wire diameter and 5.0 kW/m2

 radiant flux, the type T, J and K 

thermocouples recorded temperature increases of 68 °C, 91 °C, and 99.1 °C (122 °F, 164 °F, and 

178 °F), respectively. This would be consistent with the higher thermal conductivity of the type 

T thermocouple wire, see Table 5. The impact of wire diameter is apparent when comparing the 

four different wire diameters within a single type of thermocouple. For the type T thermocouple 

and 5 kW/m2

 of radiant flux the temperature increases for the 0.13 mm, 0.26 mm, 0.51 mm and 

0.81 mm (0.005 in, 0.010 in, 0.020 in, and 0.032 in) wire diameters were 106 °C, 93.9 °C, 77.6 

°C and 68 °C, (191 °F, 169 °F, 140 °F, and 122°F) respectively. As the wire diameter increased 

there was a reduction in the temperature increase. This would be consistent with the larger wire 

conducting more energy away from the thermocouple bead then that for a smaller diameter wire. 

In the “exposed” configuration, all twelve thermocouples responded similarly. When exposed 

and placed 6 mm (0.25 in) behind the protective clothing (“fabric-exposed-space” configuration) 

the twelve thermocouples again responded in similar fashions. In these two configurations, the 

type of thermocouple or the diameter of the thermocouple wire did not appear to have a 

significant effect on the response. When the thermocouples are placed on a substrate the 

differences between type of thermocouple material and diameter of the thermocouple wire 

becomes more significant. In the “substrate” configuration the type J and type K thermocouples 

respond similarly. However, in all cases, the type T thermocouples consistently reported lower 

temperatures than the type J or K thermocouples and the difference becomes greater as the 

diameter of the thermocouple wire increases. The effect of thermal conductivity is not apparent 

at the smallest thermocouple wire size, 0.13 mm (0.005 in). At the two largest wire sizes, 

0.51 mm and 0.81 mm (0.020 in and 0.032 in) the measured increase in temperature follows the 

ranking of the thermocouple wire thermal conductivity. The type K thermocouples, which have 

the lowest thermal conductivity reports the highest temperature increase, while the type T 

thermocouples with the highest thermal conductivity reported the least increase in temperature. 

Copper Disks and Encapsulated Thermocouples 

The two copper disks and the encapsulated thermocouple responded differently to the incident 

flux than the type J, K, and T thermocouples. In the "exposed" configuration, the copper disks 

recorded temperature increases of between 30.8 °C (55 °F) at 1.25 kW/m2

 and 105.3 °C (190 °F) 
 10 

at 5 kW/m2 while the encapsulated sensor reported temperature increases of 28.7 °C to 105.6 °C 

(52 °F to 190 °F). These temperature increases are ten to twenty times higher than for the twelve 

thermocouples in the "exposed" configuration. Of course much of the higher temperature 

increase would be consistent with the greater surface area of the disk and of the cast resin plug 

encapsulating the thermocouple. The larger surface area would allow these sensors to absorb 

more of the incident radiant flux. Mounting the sensor on a substrate did result in the sensor 

reporting higher temperature increases. The changes were in the range of 16 % to 29 % which 

was much less than the factor of ten or twenty observed in the twelve thermocouples. 

The response of the two copper disks were almost identical in both the “exposed” and 

“substrate” configurations. No extra degree of accuracy was obtained by having four 

thermocouples attached to the copper disk. Therefore, for the configurations in which the sensor 

was placed behind the protective clothing only one of the copper disks was tested. 

The copper disk and encapsulated thermocouple, when positioned behind the protective clothing, 

and having a gap between the sensor and the protective clothing, both recorded higher 

temperature increases when mounted on a substrate. However, when there is no space between 

the sensor and protective clothing both sensors recorded less of a temperature increase when 

mounted on the substrate. 

6.2 Heat Flux Measurement 

Table 22 through Table 25 give the final measurement for the four sensors whose output is 

recorded as heat flux. In the “exposed” configuration the response of the water cooled sapphire 

window radiometer is consistently less than that of the water-cooled Schmidt-Boelter total heat 

flux gauge. This is due to the sapphire window excluding some fraction of the spectral energy 

from the gas fired radiant panel. The spectral transmittance of the sapphire window is from 

0.15 μm to 5.0 μm. For the “exposed” configuration the sapphire window radiometer 

measurements of 0.9 kW/m2, 1.82 kW/m2, and 3.8 kW/m2, were respectively 71 %, 72 %, and 

76 % of those recorded by the Schmidt-Boelter total heat flux gauge. This measured response of 

the sapphire window radiometer is reasonable since at 943 K, the average surface blackbody 

temperature of the radiant panel, approximately 70 % of the radiation falls at wavelengths below 

5.8 μm [15]. The remaining radiation is excluded by the sapphire window. 

The zinc selenide window with a spectral transmittance from 0.5 μm to 22 μm allows 

approximately 98 % of the incident radiation to pass through. This is also in line with measured 

values recorded when in the “exposed” configuration. Recorded measurements of the watercooled zinc selenide radiometer of 1.18 kW/m2

, 2.40 kW/m2, and 4.84 kW/m2, were respectively 

93 %, 95 %, and 97 % of those recorded by the water-cooled Schmidt Boelter total heat flux 

gauge. The zinc selenide window radiometer was only tested in the “exposed” configuration. 

When placed behind the protective clothing (“fabric-exposed-space” configuration) the watercooled sapphire window radiometer readings were only 19 % to 22 % of that recorded by the 

water-cooled Schmidt-Boelter total heat flux gauge. With the back of the protective clothing 

being much cooler than the radiant panel, there is not only less radiant energy given off by the 
 11 

protective clothing, but it is also at a higher wavelength and therefore a greater percentage is 

excluded by the sapphire window. In the “fabric-exposed- no-space” configurations the sapphire 

window radiometer measurements were only 9 % of the Schmidt Boelter total heat flux gauge. 

The Schmidt-Boelter total heat flux gauge and the sapphire window radiometer were only placed 

on substrates when tested behind the protective clothing. When there was a space between the 

sensor and the protective clothing the Schmidt-Boelter gauge recorded a higher heat flux when 

mounted on the substrate. When there was no space between the sensor and the protective 

clothing the Schmidt-Boelter gauge recorded a lesser heat flux when mounted on the substrate. 

There was no measurable difference in the values recorded by the sapphire window radiometer 

when placed on a substrate. 

In the “exposed” configuration, the thin film heat flux gauge measurements of 0.9 kW/m2

, 

1.82 kW/m2, and 3.8 kW/m2 were respectively 58 %, 63 %, and 68 % of those recorded by the 

Schmidt-Boelter total heat flux gauge. When placed on a substrate the thin film heat flux gauge 

initially recorded higher heat flux measurements than when in the “exposed” configuration 

(Figure 91), but the recorded output decreased as the experiment continued. This was most 

noticeable at the 5 kW/m2

 exposure. No other total heat flux gauge or radiometer was tested in 

the “substrate” configuration. 

When placed behind the protective clothing sample, the thin film heat flux gauge recorded lower 

heat fluxes than the Schmidt-Boelter gauge ranging from 51 % to 82 % of the values recorded by 

the Schmidt-Bolter gauge. When there was a space between the thin film heat flux gauge and the 

protective clothing there was a slight increase in the reported heat flux when the sensor was 

mounted on the substrate. When there was no space there was no difference in the reported heat 

fluxes. 

There are different components of uncertainty in the temperatures, radiative heat flux, convective 

heat flux, conductive properties of the materials, and positioning of the sensors reported here. 

Uncertainties are grouped into two categories according to the method used to estimate them. 

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

which are evaluated by other means (16). Type B evaluation of standard uncertainty is usually 

based on scientific judgment using all the relevant information available, which may include 

previous measurement data, experience with or general knowledge of the materials or 

instruments, manufactures specifications, calibration data, and uncertainties assigned to reference 

data from handbooks. 

 

Table 6 lists the uncertainties in measurements, obtained from manufacturer’s literature 

associated with each sensor. Actual uncertainty will exceed these values. Information on 

thermal properties of sensors and materials, Table 3 to Table 5, came from manufacturers, 

handbooks, and reports. However, these data did not have uncertainties associated with them. 

7.0 Uncertainty Analysis 
 12 

Each sensor was carefully positioned before the start of an experiment. When in the “exposed” 

and “substrate” configurations the distance from the radiant panel was dictated by the desired 

heat flux. At the 1.2 kW/m2

 setting, the distance between the sensors and the radiant panel is 

1.21 m (47.5 in). A difference of ±0.2 cm (0.1 in) in the placement of the sensor would translate 

into approximately ± 0.3 % in the incident heat flux on the sensor. At the 5.0 kW/m2

 setting the 

distance between the sensor and the radiant panel is 0.57 m (22.5 in). Here a difference of ±0.2 

cm (0.1 in) in the placement of the sensor would translate into approximately ±0.6 % in the 

incident heat flux on the sensor. 

When the sensors are placed behind the protective clothing the protective clothing is positioned 

such that one of the three desired heat fluxes is imposed on the front face of the protective 

clothing, Figure 11 through Figure 14. The sensor is placed 6 mm (0.25 in) behind the protective 

clothing. The protective clothing has now become the radiator or source of heat flux for the 

sensor. Since the sensor is very close to the back side of the protective clothing even a 

difference of ± 0.2 cm would only cause a difference of ± 0.06 % in the incident heat flux on the 

sensor. 

When placing the sensors such that they were touching the protective clothing, whether exposed 

or on the substrate, it was difficult to determine how firmly the sensor was touching the 

protective clothing. Variances in the pressure exerted by a sensor on the protective clothing 

could change the contact area between the sensor and protective clothing and therefore change 

the heat transfer characteristics. This change is caused by what is known as thermal contact 

resistance. The existence of a contact resistance is due principally to surface roughness effects. 

Contact spots between the sensor and the fabric are interspersed with gaps that are, in most 

instances, air filled. Heat transfer is therefore due to conduction across the actual contact area 

and to conduction and or radiation across the gaps. 

It is interesting to note that the thermocouples when exposed and placed behind the protective 

clothing (“fabric-exposed-space” configuration) all reported a higher temperature after the 10 

min exposure than when the thermocouples were in the “exposed” only configuration. This is 

partly due to a convective boundary layer that is formed on the backside of the fabric as it is 

heated. For a vertical surface in a quiescent environment the thickness of this boundary layer 

can by calculated [15]. Given an ambient temperature of 22 °C (72 °F), and a surface 

temperature of 27 °C (81 °F) on the backside of the protective clothing, a convective boundary 

layer would be created that is approximately 35 mm (1.4 in) thick at the sensor. For a surface 

temperature of 125° C (237 °F) on the backside of the protective clothing this boundary layer 

thickness is 23 mm (0.9 in). Since the thermocouples are only 6 mm (0.25 in) from the back 

surface of the fabric they are within this boundary layer. 

When the thermocouples are in the “substrate” configuration, their response is quite similar to 

both of the copper disks and the encapsulated thermocouple in the “exposed” configuration. At 

8.0 Discussion 
 13 

the 5.0 kW/m2

 exposure the 0.13 mm (0.005 in) thermocouples on a substrate reported a 

temperature increase of between 106 °C and 112 °C (223 °F and 234 °F). Both copper disks and 

the encapsulated thermocouple reported a temperature increase of 102 °C to 106 °C (216 °F and 

223 °F) when in the “exposed” configuration. Close agreement is also realized at the 1.2 kW/m2

and 2.5 kW/m2 exposures for the smaller thermocouple wire. This agreement in temperature 

increase is expected since the copper disk with either one or four type J thermocouples attached 

to it has a similar geometry as the thermocouples mounted on a substrate. In this case the copper 

disk is the substrate. In addition, the 0.26 mm (0.010 in) type J thermocouples are used with the 

copper disks. For the encapsulated thermocouple, the substrate is the cast resin plug that the type 

T thermocouple is embedded in. As the size of the thermocouple wire diameter increases the 

reported temperature rise decreases. Again this is most notable in the type T thermocouple. The 

0.81 mm (0.032 in) type T thermocouple reported a temperature increase of 68 °C (154 °F) as 

compared to the 106 °C (223 °F) temperature increase of the smaller 0.13 mm (0.005 in) type T 

thermocouple. 

Using Equation 1 and the properties of the substrate material from Table 3, calculations were 

made to determine the surface temperature of the substrate at the point in time where the semi 

infinite slab assumption would cease to be appropriate. Of the thermocouples, in all cases the 

smallest thermocouple wire sizes came closest to these calculated values, with the type J and K 

thermocouples giving the best results. For all three heat flux levels the increase in temperatures 

recorded by the smallest type J and type K thermocouples came to within 67 % of the calculated 

increase in surface temperatures of the substrate. The type T thermocouple which has the highest 

thermal conductivity of the three thermocouple materials was slightly lower, measuring 62 % of 

the calculated temperature increase for all three heat flux levels. The copper disks came closest 

to the calculated temperature increase. Both of the copper disks had increases in temperature 

that came to within 83 % of the calculated value at 1.2kW/m2, 79 % of the calculated value at 2.5 

kW/m2

 and 76 % of the calculated value at 5.0 kW/m2. The encapsulated thermocouple gave 

results of 73 % of the calculated values for all three heat flux levels. 

When the sensors were placed behind and touching the protective clothing and exposed (“fabricexposed-no-space” configuration) or on a substrate (“fabric-substrate-no-space” configuration) 

the thermal conductivity of the thermocouple wire again becomes a factor. For all the 

thermocouples the increase in temperature reported follows the ranking of their respective 

thermal conductivities. The type K thermocouples with the lowest thermal conductivity reported 

the highest temperature increase while the type T thermocouple with the highest thermal 

conductivity reported the least temperature increase. The temperature increase of the copper 

disk, which has a high thermal conductivity has the highest temperature increase which appears 

inconsistent with what was described above. However, in this configuration the copper disk is 

acting as a heat collecting pad or heat sink to which thermocouple wires with low thermal 

conductivities are attached. This use of a heat sink or thermal pad made of a material with a high 

thermal conductivity is recommended [17] when trying to measure the surface temperature of a 

material with a low thermal conductivity, such as protective clothing. Some typical values for 

thermal conductivity of materials used in fire fighter protective clothing can be found in 

reference [18]. The thermal conductivity of the thermal lining material used in this experimental 

series is 0.035 

m K

W ⋅ . 
 14 

There is no easy method of attaching a thermocouple or any alternate transducer to a surface so 

that it can be guaranteed to indicate the true surface temperature. To do this it would be 

necessary to mount the measuring device so that it could attain, but not affect the surface 

temperature. In most cases, the presence of the thermocouple or any other measuring device will 

cause a perturbation of the temperature distribution at the point of attachment, and thus it only 

will indicate the perturbed temperature. An additional consideration when trying to measure the 

surface temperature of a fabric is the surface contact between the sensor and the fabric. 

Variances in the pressure exerted by a sensor on the protective clothing could change the contact 

resistance between the sensor and protective clothing and therefore change the heat transfer 

characteristics. As discussed earlier this change is caused by what is known as thermal contact 

resistance which is due principally to surface roughness effects. There are many methods 

described in the literature that can be used to attach sensors to materials. However, these often 

describe methods of attaching sensors to metal objects by welding, brazing, clamping, etc. Stoll 

and Hardy [19] investigated several devices used for the measurement of a material’s surface 

temperature. They attempted to measure the surface temperature of an oak tanned leather 

material and noted the difficulty of quantifying the contact pressure of the sensor on the material. 

Lawson and Twilley [11] describe a method of attaching thermocouples to a fabric for the 

purpose of measuring surface temperature. 

When placed behind the protective clothing and with a space of 6 mm (0.25 in) between the 

sensors and the protective clothing (“fabric-exposed-space” configuration or “fabric-substratespace” configuration) all except one sensor measured higher temperatures when on the substrate. 

This one was the copper disk with 4 thermocouples attached and only at the 5.0 kW/m2

 exposure. 

In this configuration there is a convective flow that is due to the back of the fabric heating and a 

convective flow that is caused by the substrate itself. 

The use of thermocouples presents challenges including the ambiguities involved in heat flux 

calculations and skin burn injury estimations. For the purpose of measuring the surface 

temperature of a fabric with a low thermal conductivity, a thermocouple mounted to a heat sink 

that is then attached to the fabric appears to give the best or most representative results. 

Although not specifically designed for this purpose, the copper disk used in these experiments 

emulates this configuration. The copper disk which is a material with a high thermal 

conductivity is placed against the protective clothing and acts as a heat sink. Attached to the 

copper disk are 0.26 mm (0.010 in) type J thermocouples which are measuring the temperature 

of the copper disk. Data from the “Fabric exposed no space” configuration indicates that the 

copper disk reported a greater temperature increase than any of the thermocouples. For an 

imposed heat flux on the front surface of the protective clothing of 5 kW/m2 the copper disk 

recorded a temperature increase of 91 °C (194 °F). For this same heat flux the 0.26 mm (0.010 

in) type J thermocouple when placed directly on the protective clothing recorded a temperature 

increase of 46 °C (83 °F). Reference 17 suggests that the thermocouple attached to the heat sink 

be made from wires that have as low a thermal conductivity as possible. Of the three 

thermocouple materials used in these experiments the type K thermocouple has the lowest 

thermal conductivity. This suggests that if type K thermocouples had been attached to the 

copper disk that the recorded temperature may have been higher. From the thermocouples tested 

in this experimental series the 0.13 mm (0.005 in) type K thermocouple would give the most 
 15 

accurate results. The use of a thermocouple made of such a small diameter wire does not pose a 

problem in small scale laboratory work. However, for large scale testing or field work where 

these thermal pads would be subject to movement the small diameter lead wires may be easily 

broken. In this case a compromise would need to be made between accuracy and ruggedness of 

the measuring device. 

The use of copper disks to determine heat flux by measuring the initial temperature rise of the 

copper disk is a practice that is in use [20]. The following expression may be used to calculate 

the incident heat flux on the copper disk surface. 





 





∆

∆















  =



 





∆

∆ = tT

A

MC

t

T

q C l p

c ρ p &

Equation 4 

Where: c q& = incident heat flux 2

m

kW

 ρ = density of copper 3

m

kg

 Cp = specific heat of copper kg k

kJ ⋅ 

 l = thickness of copper disk m

 ∆T = copper disk temperature rise during exposure to radiant panel, initial linear 

temperature rise k

 ∆t = time period corresponding to ∆T temperature rise s

 M = mass of copper disk kg

 A = cross sectional area of copper disk 2

m

The use of Equation 4 is limited to the initial linear portion of the time-temperature curve that is 

obtained during the copper disk’s exposure to the heat source [20]. Analysis of the data at the 

1.2 kW/m2 exposure indicates that after 30 s the time-temperature curve is no longer linear. 

However, within this time frame and after the initial temperature transient effects were 

eliminated the calculated heat flux by use of Equation 4 was 1.15 kW/ m

2

. At 2.5 kW/m2 and 

5.0 kW/m2 the initial linear portion of the time-temperature curve is over a period of 

approximately 20 s and 15 s, respectively. At exposures to higher heat fluxes the period over 

which this time-temperature curve would be linear becomes smaller. Therefore, for exposures 

and time periods of interest to this experimental series the use of copper disk calorimeter is not 

recommended. 

The manufacturer of the encapsulated thermocouple claims that heat flux can be calculated 

through the temperature rise of the encapsulated thermocouple by use of a proprietary method. 

We did not investigate this capability. 
 16 

A series of experiments was conducted to investigate the response of different thermal sensors to 

three different heat fluxes and in six different configurations. It has been shown that the sensor 

configuration, thermal properties of the sensor itself, and the incident radiant flux all affected the 

final temperature increases or heat flux measurements. 

For measuring the heat flux incident on a surface the water cooled Schmidt-Boelter total heat 

flux gauge yields values closest to what is predicted. The sapphire window radiometer with its 

spectral range on 0.15 μm to 5.5 μm only measured a portion of the radiant heat flux. Both the 

sapphire and zinc selenide window radiometers do not measure the convective portion of heat 

energy that may be present. The copper disk measurement of temperature can be converted into 

a heat flux by use of Equation 4. However this method is only appropriate during the initial 

linear temperature rise of the copper disk. The lowest heat flux of 1.2 kW/m2

 the temperature 

rise of the copper disk was linear for only the first 30 s. Therefore for the purpose of a 10 min 

exposure even at the lowest heat fluxes used in these experiments, the copper disk would be 

inappropriate. Logistically, the water cooled Schmidt-Boelter gauge may be difficult to 

implement when dozens of measurements are required in the field with an instrumented 

mannequin or actual fire fighter. 

For temperature measurements, it has been shown that there is a wide variation in reported 

measurements among sensors, even those made of the same material. For measuring the surface 

temperature of a fabric, it appears that the use of a thermal pad made of a material with a high 

thermal conductivity to which is attached a thermocouple with lead wires made of a material 

with a low thermal conductivity, may be the most appropriate. In this experimental series the 

copper disk emulated this arrangement. The use of small thermal pads for temperature 

measurements should not impose any more difficulty in field use than thermocouples. 

Regardless of the method used for determining surface temperature, a methodology needs to be 

developed that can take this temperature and translate it to potential burn injury. This would be a 

subject for further research. 

This work was funded by the National Institute of Occupational Safety and Health, Center for 

Disease Control, U.S. Department of Health and Human Services. Appreciation is extended to 

Tim Pizatella and Thomas Hodous of NIOSH for their support. To Daniel Madrzykowski and 

David Stroup for providing guidance in the experimental set up and sensor selection. Finally to 

William Twilley who constructed the experimental apparatus up and performed all of the 

experiments. 

9.0 Conclusions 

10.0 Acknowledgements 
 17 

Table 1. Description of sensors. 

Omega Engineering type J (Iron versus Copper Nickel) thermocouple – 0.81 mm (0.032 in) wire 

diameter. Thermocouple bead coated with a paint with an emissivity of 0.96. 

Omega Engineering type J (Iron versus Copper Nickel) thermocouple – 0.51 mm (0.020 in) wire 

diameter. Thermocouple bead coated with a paint with an emissivity of 0.96. 

Omega Engineering type J (Iron versus Copper Nickel) thermocouple – 0.26 mm (0.010 in) wire 

diameter. Thermocouple bead coated with a paint with an emissivity of 0.96. 

Omega Engineering type J (Iron versus Copper Nickel) thermocouple – 0.13 mm (0.005 in) wire 

diameter. Thermocouple bead coated with a paint with an emissivity of 0.96. 

Omega Engineering type K (Nickel-Chromium versus Nickel-Aluminum) thermocouple – 0.81 

mm (0.032 in) wire diameter. Thermocouple bead coated with a paint with an emissivity of 0.96. 

Omega Engineering type K (Nickel-Chromium versus Nickel-Aluminum) thermocouple – 0.51 

mm (0.020 in) wire diameter. Thermocouple bead coated with a paint with an emissivity of 0.96. 

Omega Engineering type K (Nickel-Chromium versus Nickel-Aluminum) thermocouple – 0.26 

mm (0.010 in) wire diameter. Thermocouple bead coated with a paint with an emissivity of 0.96. 

Omega Engineering type K (Nickel-Chromium versus Nickel-Aluminum) thermocouple – 0.13 

mm (0.005 in) wire diameter. Thermocouple bead coated with a paint with an emissivity of 0.96. 

Omega Engineering type T (Copper versus Copper Nickel) thermocouple – 0.81 mm (0.032 in) 

wire diameter. Thermocouple bead coated with a paint with an emissivity of 0.96. 

Omega Engineering type T (Copper versus Copper Nickel) thermocouple – 0.51 mm (0.020 in) 

wire diameter. Thermocouple bead coated with a paint with an emissivity of 0.96. 

Omega Engineering type T (Copper versus Copper Nickel) thermocouple – 0.26 mm (0.010 in) 

wire diameter. Thermocouple bead coated with a paint with an emissivity of 0.96. 

Omega Engineering type T (Copper versus Copper Nickel) thermocouple – 0.13 mm (0.005 in) 

wire diameter. Thermocouple bead coated with a paint with an emissivity of 0.96. 

Copper disk with 4 Omega Engineering type J (Iron versus Copper Nickel) thermocouples, 0.26 

mm (0.010) wire diameter attached. Disk diameter 3.99 cm, Disk thickness 0.162 cm, Disk mass 

0.0174 kg. Disk surface coated with a paint with an emissivity of 0.96. 

Copper disk with 1 Omega Engineering type J (Iron versus Copper Nickel) thermocouple, 0.26 

mm (0.010) wire diameter attached. Disk diameter 3.99 cm, Disk thickness 0.157 cm, Disk mass 

0.0173 kg. Disk surface coated with a paint with an emissivity of 0.96. 

E. I. Du Pont encapsulated type T (Copper versus Copper Nickel) thermocouple 

Medtherm Corporation water cooled Schmidt-Boelter total heat flux transducer. Model number 

64-1T-1R-20898. Nominal range of 0 kW/m2

 to 10 kW/m2 with a corresponding voltage range 

of 0 mV to 9 mV. The time constant to reach 63 % of final value for this heat flux gauge is not 

more than 290 ms with a corresponding time to reach 95 % of the final output of not more than 

1 s. 
 18 

Medtherm Corporation water cooled sapphire window radiometer. Model number 64-10SB20/SW-1C-150. Spectral transmittance of 0.15 μm to 5.0 μm. Nominal range of 0 kW/m2

 to 10 

kW/m2

 with a corresponding voltage range of 0 to 7.5 mV. The time constant to reach 63 % of 

final value is not more than 290 ms with a corresponding time to reach 95 % of the final output 

of not more than 1 s. 

Medtherm Corporation water cooled zinc selenide window radiometer. Model number 64-10SB20/ZnSeW-1C-150. Spectral transmittance of 0.5 μm to 22 μm. Nominal range of 0 kW/m2

 to 

100 kW/m2 with a corresponding voltage range of 0 to 8.6 mV. The time constant to reach 63 % 

of final value is not more than 290 ms with a corresponding time to reach 95 % of the final 

output of not more than 1 s. View angle of 150 °. 

Vatell Corporation thin film heat flux gauge. Model number B02. Dimensions 2.5 cm X 2.5 cm, 

0.4 mm thick. Rise time 60 ms (10 % - 90 % of signal). Emissivity of 0.94. 

Table 2. Experimental Configurations 

Configuration Description 

1. Exposed The sensor is exposed to the radiant panel. 

2. Substrate The sensor is mounted on a substrate such that the surface of 

the sensor is flush with the surface of the substrate and is 

exposed to the radiant panel. 

3. Fabric-exposed-no space A section of fire fighter protective clothing is placed between 

the sensor and the radiant panel. The sensor is not mounted on 

a substrate. The sensor is touching the back of the protective 

clothing material. 

4. Fabric-exposed-space A section of fire fighter protective clothing is placed between 

the sensor and the radiant panel. The sensor is not mounted on 

a substrate. There is an air gap between the sensor and the 

back of the protective clothing of 6 mm (0.25 in). 

5. Fabric-substrate-no space A section of fire fighter protective clothing is placed between 

the sensor and the radiant panel. The sensor is mounted on a 

substrate such that the surface of the sensor is flush with the 

surface of the substrate. The sensor is touching the back of the 

protective clothing material. 

6. Fabric-substrate-space A section of fire fighter protective clothing is placed between 

the sensor and the radiant panel. The sensor is mounted on a 

substrate such that the surface of the sensor is flush with the 

surface of the substrate. There is an air gap between the sensor 

and the back of the protective clothing of 6 mm (0.25 in). 

Table 3. Thermal properties of “Bakelite” substrate material 

Thermal conductivity 

m K

W ⋅

Density 

3

m

kg

Specific Heat 

kg K

J ⋅

Emissivity 

0.24 1277 1465 .96 
 19 

Table 4. Thermal properties of protective clothing 

Material* Thermal 

conductivity 

m K

W ⋅

Density 

3

m

kg

Specific Heat 

kg K

J ⋅

Outer shell- PBITM Kevlar® 

KombatTM 0.048 321.8 N/A 

Moisture barrier- Nomex® E-89 

Crosstech® 0.035 143.1 N/A 

Thermal liner- Aralite® 0.035 74.2 N/A 

* PBITM is a registered trademark of the Celanese Corporation. 

 Nomex® and Kevlar® are registered trademarks of E. I. Du Pont 

 Crosstech® is a registered trademark of W. L. Gore and Associates 

 Aralite® and KombatTM are registered trademarks of Southern Mills 

Table 5. Thermal conductivity of thermocouple materials 

Thermocouple Type Materials 

Thermal Conductivity 

m K

W ⋅

Iron 75 J 

Copper Nickel 21 

Nickel Chromium 19 K Nickel Aluminum 29 

Copper 401 T Copper Nickel 21 

Table 6. Measurement uncertainties of sensors 

Sensor 

Manufacturer’s Stated 

Uncertainty 

(%) 

Repeatability in 

Experiments 

(%) 

Thermocouples ± 1 ± 0.5 

Schmidt-Boelter total heat flux gauge ± 3 ± 8.6 

Sapphire window radiometer ± 3 ± 10.6 

Zinc Selenide window radiometer ± 3 ± 4.7 

Copper disk ± 1 ± 0.3 

Encapsulated thermocouple ± 1 ± 0.3 

Thin Film heat flux gauge. ± 2.5 ± 9.3 
 20 

Table 7. Response of 0.13 mm (0.005 in) type J thermocouple after 10 min exposure. 

Configuration Temperature 

increase at 1.2 

kW/m2

 exposure 

(°C) 

Temperature 

increase at 2.5 

kW/m2 exposure 

(°C) 

Temperature 

increase at 5.0 

kW/m2 exposure 

(°C) 

Exposed 2.4 ± 1.1 4.1 ± 1.6 5.6 ± 1.2 

Substrate 31.3 ± 1.1 60.0 ± 0.9 110.8 ± 3.1 

Fabric-Exposed-No Space 19.5 ± 3.1 32.5 ± 4.4 59.1 ± 4.8 

Fabric-Exposed-Space 2.6 ± 1.4 9.3 ± 5.1 13.6 ± 6.5 

Fabric-Substrate-No Space 17.2 ± 0.6 29.1 ± 0.4 58.6 ± 2.1 

Fabric-Substrate-Space 11.2 ± 0.6 18.2 ± 0.7 31.0 ± 0.9 

Table 8. Response of 0.26 mm (0.010 in) type J thermocouple after 10 min exposure. 

Configuration Temperature 

increase at 1.2 

kW/m2

 exposure 

(°C) 

Temperature 

increase at 2.5 

kW/m2 exposure 

(°C) 

Temperature 

increase at 5.0 

kW/m2 exposure 

(°C) 

Exposed 2.2 ± 0.7 3.5 ± 0.8 6.0 ± 0.8 

Substrate 29.7 ± 1.6 57.0 ± 0.9 106.0 ± 1.5 

Fabric-Exposed-No Space 16.7 ± 2.1 27.1 ± 1.3 45.9 ± 3.0 

Fabric-Exposed-Space 4.1 ± 1.6 9.0 ± 3.1 11.2 ± 3.4 

Fabric-Substrate-No Space 18.6 ± 0.9 31.9 ± 0.5 59.1 ± 1.3 

Fabric-Substrate-Space 11.4 ± 0.5 18.1 ± 0.6 25.4 ± 1.2 

Table 9. Response of 0.51 mm (0.020 in) type J thermocouple after 10 min exposure. 

Configuration Temperature 

increase at 1.2 

kW/m2 exposure 

(°C) 

Temperature 

increase at 2.5 

kW/m2 exposure 

(°C) 

Temperature 

increase at 5.0 

kW/m2 exposure 

(°C) 

Exposed 2.1 ± 0.6 3.5 ± 0.9 6.3 ± 0.8 

Substrate 28.5 ± 1.8 54.5 ± 1.8 102.0 ± 2.2 

Fabric-Exposed-No Space 11.5 ± 1.0 17.6 ± 1.1 32.6 ± 2.4 

Fabric-Exposed-Space 3.7 ± 0.9 6.0 ± 1.3 10.7 ± 1.8 

Fabric-Substrate-No Space 17.3 ± 0.8 29.8 ± 0.5 63.0 ± 1.4 

Fabric-Substrate-Space 10.4 ± 0.5 16.3 ± 0.6 29.0 ± 1.2 
 21 

Table 10. Response of 0.81 mm (0.032 in) type J thermocouple after 10 min exposure. 

Configuration Temperature 

increase at 1.2 

kW/m2

 exposure 

(°C) 

Temperature 

increase at 2.5 

kW/m2 exposure 

(°C) 

Temperature 

increase at 5.0 

kW/m2 exposure 

(°C) 

Exposed 2.2 ± 0.6 4.5 ± 0.7 9.0 ± 1.0 

Substrate 25.4 ± 2.0 48.5 ± 3.0 91.0 ± 4.8 

Fabric-Exposed-No Space 10.3 ± 0.7 16.3 ± 1.9 29.2 ± 2.3 

Fabric-Exposed-Space 3.6 ± 1.2 6.3 ± 0.9 10.2 ± 1.6 

Fabric-Substrate-No Space 16.4 ± 0.7 28.3 ± 0.5 N/A 

Fabric-Substrate-Space 9.0 ± 0.8 13.5 ± 0.6 N/A 

Table 11. Response of 0.13 mm (0.005 in) type K thermocouple after 10 min exposure. 

Configuration Temperature 

increase at 1.2 

kW/m2

 exposure 

(°C) 

Temperature 

increase at 2.5 

kW/m2 exposure 

(°C) 

Temperature 

increase at 5.0 

kW/m2 exposure 

(°C) 

Exposed 2.7 ± 0.8 4.7 ± 1.0 8.3 ± 1.1 

Substrate 30.8 ± 1.5 59.5 ± 2.2 112.0 ± 4.6 

Fabric-Exposed-No Space 23.7 ± 1.1 38.2 ± 2.3 69.5 ± 3.8 

Fabric-Exposed-Space 3.3 ± 3.8 8.7 ± 6.5 20.2 ± 7.3 

Fabric-Substrate-No Space 17.3 ± 0.8 29.8 ± 0.5 59.6 ± 1.1 

Fabric-Substrate-Space 10.4 ± 0.9 15.3 ± 0.7 24.0 ± 1.5 

Table 12. Response of 0.26 mm (0.010 in) type K thermocouple after 10 min exposure. 

Configuration Temperature 

increase at 1.2 

kW/m2 exposure 

(°C) 

Temperature 

increase at 2.5 

kW/m2 exposure 

(°C) 

Temperature 

increase at 5.0 

kW/m2 exposure 

(°C) 

Exposed 2.1 ± 0.8 3.3 ± 0.8 5.5 ± 0.8 

Substrate 29.2 ± 2.2 56.3 ± 2.0 105.3 ± 3.8 

Fabric-Exposed-No Space 20.3 ± 1.4 31.5 ± 2.2 51.1 ± 3.6 

Fabric-Exposed-Space 3.5 ± 2.2 5.8 ± 1.9 12.1 ± 4.8 

Fabric-Substrate-No Space 20.6 ± 0.8 35.6 ± 0.5 71.0 ± 1.2 

Fabric-Substrate-Space 12.0 ± 0.7 18.3 ± 1.0 27.5 ± 2.0 
 22 

Table 13. Response of 0.51 mm (0.020 in) type K thermocouple after 10 min exposure. 

Configuration Temperature 

increase at 1.2 

kW/m2

 exposure 

(°C) 

Temperature 

increase at 2.5 

kW/m2 exposure 

(°C) 

Temperature 

increase at 5.0 

kW/m2 exposure 

(°C) 

Exposed 2.5 ± 0.6 4.3 ± 0.7 7.7 ± 0.6 

Substrate 29.0 ± 1.2 56.0 ± 1.2 105.1 ± 1.2 

Fabric-Exposed-No Space 14.4 ± 1.3 23.2 ± 1.7 35.6 ± 2.3 

Fabric-Exposed-Space 3.9 ± 1.0 7.0 ± 1.7 11.0 ± 1.7 

Fabric-Substrate-No Space 19.0 ± 0.8 32.6 ± 0.5 66.3 ± 1.1 

Fabric-Substrate-Space 11.6 ± 0.6 18.2 ± 0.6 29.3 ± 1.2 

Table 14. Response of 0.81 mm (0.032 in) type K thermocouple after 10 min exposure. 

Configuration Temperature 

increase at 1.2 

kW/m2

 exposure 

(°C) 

Temperature 

increase at 2.5 

kW/m2 exposure 

(°C) 

Temperature 

increase at 5.0 

kW/m2 exposure 

(°C) 

Exposed 2.5 ± 0.6 4.4 ± 0.8 8.3 ± 0.4 

Substrate 27.6 ± 1.1 53.2 ± 1.4 99.1 ± 3.3 

Fabric-Exposed-No Space 6.4 ± 5.6 6.0 ± 3.1 30.3 ± 2.7 

Fabric-Exposed-Space 3.7 ± 1.1 3.7 ± 3.2 11.0 ± 2.1 

Fabric-Substrate-No Space 18.0 ± 0.7 30.9 ± 0.5 61.1 ± 1.1 

Fabric-Substrate-Space 10.9 ± 0.6 17.6 ± 0.6 29.3 ± 0.8 

Table 15. Response of 0.13 mm (0.005 in) type T thermocouple after 10 min exposure. 

Configuration Temperature 

increase at 1.2 

kW/m2 exposure 

(°C) 

Temperature 

increase at 2.5 

kW/m2 exposure 

(°C) 

Temperature 

increase at 5.0 

kW/m2 exposure 

(°C) 

Exposed 1.6 ± 0.6 2.9 ± 1.1 5.1 ± 1.4 

Substrate 29.6 ± 1.1 57.1 ± 1.8 106.0 ± 3.4 

Fabric-Exposed-No Space 17.1 ± 1.1 27.0 ± 3.1 42.6 ± 4.2 

Fabric-Exposed-Space 3.2 ± 3.0 5.5 ± 3.0 11.0 ± 7.5 

Fabric-Substrate-No Space 15.6 ± 0.5 26.8 ± 0.4 55.7 ± 1.3 

Fabric-Substrate-Space 10.4 ± 0.6 16.9 ± 0.5 28.3 ± 0.7 
 23 

Table 16. Response of 0.26 mm (0.010 in) type T thermocouple after 10 min exposure. 

Configuration Temperature 

increase at 1.2 

kW/m2

 exposure 

(°C) 

Temperature 

increase at 2.5 

kW/m2 exposure 

(°C) 

Temperature 

increase at 5.0 

kW/m2 exposure 

(°C) 

Exposed 1.7 ± 0.6 2.8 ± 1.2 4.2 ± 1.0 

Substrate 25.7 ± 1.1 49.9 ± 1.0 93.9 ± 2.5 

Fabric-Exposed-No Space 9.9 ± 1.8 14.9 ± 1.6 29.0 ± 2.0 

Fabric-Exposed-Space 3.0 ± 1.2 5.0 ± 1.5 9.5 ± 2.7 

Fabric-Substrate-No Space 14.6 ± 0.5 25.2 ± 0.4 51.4 ± 1.0 

Fabric-Substrate-Space 9.6 ± 0.6 15.0 ± 0.7 24.2 ± 0.7 

Table 17. Response of 0.51 mm (0.020 in) type T thermocouple after 10 min exposure. 

Configuration Temperature 

increase at 1.2 

kW/m2

 exposure 

(°C) 

Temperature 

increase at 2.5 

kW/m2 exposure 

(°C) 

Temperature 

increase at 5.0 

kW/m2 exposure 

(°C) 

Exposed 1.8 ± 0.6 2.9 ± 0.7 5.6 ± 0.6 

Substrate 21.0 ± 0.8 40.7 ± 1.3 77.6 ± 3.4 

Fabric-Exposed-No Space 7.6 ± 1.0 12.0 ± 0.9 22.1 ± 1.9 

Fabric-Exposed-Space 3.0 ± 0.9 5.3 ± 1.0 8.6 ± 1.6 

Fabric-Substrate-No Space 13.0 ± 0.5 22.0 ± 0.3 44.6 ± 1.1 

Fabric-Substrate-Space 8.1 ± 0.6 12.1 ± 0.7 19.0 ± 0.6 

Table 18. Response of 0.81 mm (0.032 in) type T thermocouple after 10 min exposure. 

Configuration Temperature 

increase at 1.2 

kW/m2 exposure 

(°C) 

Temperature 

increase at 2.5 

kW/m2 exposure 

(°C) 

Temperature 

increase at 5.0 

kW/m2 exposure 

(°C) 

Exposed 2.0 ± 0.7 3.2 ± 0.9 6.5 ± 0.8 

Substrate 18.6 ± 1.0 35.7 ± 1.9 68.0 ± 4.4 

Fabric-Exposed-No Space 6.0 ± 0.7 10.0 ± 1.0 17.1 ± 1.5 

Fabric-Exposed-Space 2.5 ± 0.6 5.0 ± 0.8 8.2 ± 1.2 

Fabric-Substrate-No Space 12.1 ± 0.6 20.2 ± 0.3 41.2 ± 1.2 

Fabric-Substrate-Space 7.1 ± 0.9 10.0 ± 0.6 15.7 ± 0.6 
 24 

Table 19. Response of encapsulated thermocouple after 10 min exposure. 

Configuration Temperature 

increase at 1.2 

kW/m2

 exposure 

(°C) 

Temperature 

increase at 2.5 

kW/m2 exposure 

(°C) 

Temperature 

increase at 5.0 

kW/m2 exposure 

(°C) 

Exposed 28.7 ± 1.1 55.7 ± 1.8 105.6 ± 0.9 

Substrate 34.2 ± 0.7 64.5 ± 1.3 118.5 ± 1.6 

Fabric-Exposed-No Space 23.1 ± 0.9 39.9 ± 0.8 80.7 ± 1.4 

Fabric-Exposed-Space 8.0 ± 0.8 13.0 ± 0.5 25.3 ± 1.1 

Fabric-Substrate-No Space 17.1 ± 0.3 31.7 ± 0.6 64.2 ± 0.7 

Fabric-Substrate-Space 9.0 ± 0.7 15.3 ± 0.5 31.3 ± 1.4 

Table 20. Response of copper disk with one thermocouple attached after 10 min exposure. 

Configuration Temperature 

increase at 1.2 

kW/m2

 exposure 

(°C) 

Temperature 

increase at 2.5 

kW/m2 exposure 

(°C) 

Temperature 

increase at 5.0 

kW/m2 exposure 

(°C) 

Exposed 31.6 ± 0.8 57.9 ± 1.0 105.3 ± 1.5 

Substrate 39.1 ± 0.7 72.1 ± 0.7 129.8 ± 1.2 

Fabric-Exposed-No Space N/A N/A N/A 

Fabric-Exposed-Space N/A N/A N/A 

Fabric-Substrate-No Space N/A N/A N/A 

Fabric-Substrate-Space N/A N/A N/A 

Table 21. Response of copper disk with four thermocouples attached after 10 min exposure. 

Configuration Temperature 

increase at 1.2 

kW/m2 exposure 

(°C) 

Temperature 

increase at 2.5 

kW/m2 exposure 

(°C) 

Temperature 

increase at 5.0 

kW/m2 exposure 

(°C) 

Exposed 30.8 ± 1.1 56.0 ± 1.2 101.8 ± 2.5 

Substrate 38.6 ± 0.6 72.1 ± 1.1 131.5 ± 1.4 

Fabric-Exposed-No Space 25.5 ± 0.5 48.4 ± 1.2 91.3 ± 4.0 

Fabric-Exposed-Space 8.6 ± 0.4 14.8 ± 1.1 37.2 ± 2.3 

Fabric-Substrate-No Space 20.6 ± 0.7 36.0 ± 0.6 69.2 ± 0.8 

Fabric-Substrate-Space 12.4 ± 0.5 20.0 ± 0.8 33.0 ± 1.1 
 25 

Table 22. Response of thin film heat flux sensor after 10 min exposure 

Configuration Measured heat flux 

at 1.2 kW/m2

exposure 

(kW/m2) 

Measured heat flux 

at 2.5 kW/m2

exposure 

(kW/m2) 

Measured heat flux 

at 5.0 kW/m2

exposure 

(kW/m2) 

Exposed 0.74 ± 0.07 1.58 ± 0.16 3.32 ± 0.40 

Substrate 0.78 ± 0.08 1.65 ± 0.11 3.14 ± 0.23 

Fabric-Exposed-No Space 0.40 ± 0.02 0.85 ± 0.07 1.81 ± 0.06 

Fabric-Exposed-Space 0.16 ± 0.03 0.29 ± 0.08 0.54 ± 0.07 

Fabric-Substrate-No Space 0.45 ± 0.01 0.85 ± 0.01 1.82 ± 0.03 

Fabric-Substrate-Space 0.27 ± 0.02 0.44 ± 0.04 0.75 ± 0.11 

Table 23. Response of Sapphire window radiometer after 10 min exposure. 

Configuration Measured heat flux 

at 1.2 kW/m2

exposure 

(kW/m2) 

Measured heat flux 

at 2.5 kW/m2

exposure 

(kW/m2) 

Measured heat flux 

at 5.0 kW/m2

exposure 

(kW/m2) 

Exposed 0.90 ± 0.03 1.82 ± 0.03 3.80 ± 0.10 

Substrate N/A N/A N/A 

Fabric-Exposed-No Space 0.06 ± 0.01 0.11 ± 0.01 N/A 

Fabric-Exposed-Space 0.05 ± 0.01 0.11 ± 0.01 N/A 

Fabric-Substrate-No Space 0.05 ± 0.01 0.10 ± 0.01 N/A 

Fabric-Substrate-Space 0.06 ± 0.01 0.13 ± 0.01 N/A 

Table 24. Response of Schmidt-Boelter Total Heat Flux Gauge after 10 min exposure. 

Configuration Measured heat flux 

at 1.2 kW/m2

exposure 

(kW/m2

) 

Measured heat flux 

at 2.5 kW/m2

exposure 

(kW/m2

) 

Measured heat flux 

at 5.0 kW/m2

exposure 

(kW/m2

) 

Exposed 1.27 ± 0.03 2.52 ± 0.11 5.0 ± 0.09 

Substrate N/A N/A N/A 

Fabric-Exposed-No Space 0.63 ± 0.01 1.17 ± 0.02 N/A 

Fabric-Exposed-Space 0.22 ± 0.07 0.57 ± 0.08 N/A 

Fabric-Substrate-No Space 0.55 ± 0.11 1.03 ± 0.02 N/A 

Fabric-Substrate-Space 0.33 ± 0.03 0.74 ± 0.04 N/A 
 26 

Table 25. Response of Zinc Selenide radiometer after 10 min exposure. 

Configuration Measured heat flux 

at 1.2 kW/m2

exposure 

(kW/m2) 

Measured heat flux 

at 2.5 kW/m2

exposure 

(kW/m2) 

Measured heat flux 

at 5.0 kW/m2

exposure 

(kW/m2) 

Exposed 1.18 ±0.05 2.40±0.03 4.84±0.42 

Substrate N/A N/A N/A 

Fabric-Exposed-No Space N/A N/A N/A 

Fabric-Exposed-Space N/A N/A N/A 

Fabric-Substrate-No Space N/A N/A N/A 

Fabric-Substrate-Space N/A N/A N/A 
 27 

Figure 1. Copper disk in the exposed position, no substrate. 

Figure 2. Copper disk in substrate. 
 28 

Figure 3. 12 thermocouples exposed. 

Figure 4. 12 thermocouples mounted on substrate. 
 29 

Figure 5. Encapsulated type T (Copper versus Copper Nickel) thermocouple exposed. 

Figure 6. Encapsulated type T (Copper versus Copper Nickel) thermocouple mounted in 

substrate. 
 30 

Figure 7. Thin film sensor in the exposed position. 

Figure 8. Test apparatus. This figure show the protective clothing set between the radiant panel 

and the sensor. 

Radiant 

Panel 

Test 

Sensor 

Protective 

Clothing 

Trolley 

Assembly 
 31 

Figure 9. Experimental set up for “Exposed” configuration. Drawing not to scale. 

Figure 10. Experimental set up for “Substrate” configuration. Sensor is mounted in the substrate 

such that its surface is flush with the substrate surface. Drawing not to scale. 

Radiant 

Panel 

Sensor 

Sensor leads 

Radiant 

Panel Substrate 

Sensor 

Sensor leads 
 32 

Figure 11. Experimental set up for " Fabric-Exposed-No Space" configuration. Sensor is 

touching the back of the protective clothing. Drawing not to scale. 

Figure 12. Experimental set up for "Fabric-Exposed-Space" configuration. There is an air gap 

of 6mm (0.25 in) between the sensor and the protective clothing. Drawing not to scale. 

Radiant 

Panel 

Protective 

Clothing 

Sensor leads 

Sensor 

Radiant 

Panel Protective 

Clothing 

Sensor 

Sensor leads 

6 mm air gap between

protective clothing and

sensor 
 33 

Figure 13. Experimental set up for "Fabric-Substrate-No Space" configuration. Sensor is 

mounted in substrate and surface of sensor and substrate are touching protective clothing. 

Drawing not to scale. 

Figure 14. Experimental set up for "Fabric-Substrate-Space" configuration. Sensor is mounted 

in substrate and there is a 6 mm (0.25 in) air gap between the protective clothing and the sensor. 

Drawing not to scale. 

Radiant 

Panel Protective 

Clothing 

Substrate 

Sensor 

Sensor leads 

Radiant 

Panel Protective 

Clothing 

6 mm air gap between

protective clothing and

sensor 

Sensor leads 

Substrate 

Sensor
 34 

Figure 15. Three layers that make up typical fire fighter protective clothing. 

Figure 16. Response of all type J thermocouples, exposed, 1.2 kW/m2

. 

Moisture 

Barrier 

Thermal Liner Outer Shell 

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0.13 mm

0.26 mm

0.51 mm

0.81 mm
 35 

Figure 17. Response of all type J thermocouples, exposed, 5.0 kW/m2

. 

Figure 18. Response of all type K thermocouples, exposed, 1.2 kW/m2

. 

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0.81 mm

0.51 mm

0.26 mm

0.13 mm
 36 

Figure 19. Response of all type K thermocouples, exposed, 5.0 kW/m2

. 

Figure 20. Response of all type T thermocouples, exposed, 1.2 kW/m2

. 

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0.81 mm

0.51 mm

0.26 mm

0.13 mm
 37 

Figure 21. Response of all type T thermocouples, exposed, 5.0 kW/m2

. 

Figure 22. Response of all type J thermocouples, substrate, 1.2 kW/m2

. 

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0.81 mm

0.51 mm

0.26 mm

0.13 mm

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0.81 mm

0.51 mm

0.26 mm

0.13 mm
 38 

Figure 23. Response of all type J thermocouples, substrate, 5.0 kW/m2

. 

Figure 24. Response of all type K thermocouples, substrate, 1.2 kW/m2

. 

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0.81 mm

0.51 mm

0.26 mm

0.13 mm
 39 

Figure 25. Response of all type K thermocouples, substrate, 5.0 kW/m2

. 

Figure 26. Response of all type T thermocouples, substrate, 1.2 kW/m2

. 

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0.81 mm

0.51 mm

0.26 mm

0.13 mm

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0.81 mm

0.51 mm

0.26 mm

0.13 mm
 40 

Figure 27. Response of all type T thermocouples, substrate, 5.0 kW/m2

. 

Figure 28. Response of all type J thermocouples, fabric-exposed-no space, 1.2 kW/m2

. 

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0.81 mm

0.51 mm

0.26 mm

0.13 mm

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0.81 mm

0.51 mm

0.26 mm

0.13 mm
 41 

Figure 29. Response of all type J thermocouples, fabric-exposed-no space 5.0 kW/m2

. 

Figure 30. Response of all type K thermocouples, fabric-exposed-no space, 1.2 kW/m2

. 

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0.81 mm

0.51 mm

0.26 mm

0.13 mm

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0.81 mm

0.51 mm

0.26 mm

0.13 mm
 42 

Figure 31. Response of all type K thermocouples, fabric-exposed-no space, 5.0 kW/m2

. 

Figure 32. Response of all type T thermocouples, fabric-exposed-no space, 1.2 kW/m2

. 

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0.81 mm

0.51 mm

0.26 mm

0.13 mm

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0.81 mm

0.51 mm

0.26 mm

0.13 mm
 43 

Figure 33. Response of all type T thermocouples, fabric-exposed-no space, 5.0 kW/m2

. 

Figure 34. Response of all type J thermocouples, fabric-exposed-space, 1.2 kW/m2

. 

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0.81 mm

0.51 mm

0.26 mm

0.13 mm
 44 

Figure 35. Response of all type J thermocouples, fabric-exposed-space, 5.0 kW/m2

. 

Figure 36. Response of all type K thermocouples, fabric-exposed-space, 1.2 kW/m2

. 

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0.81 mm

0.51 mm

0.26 mm

0.13 mm
 45 

Figure 37. Response of all type K thermocouples, fabric-exposed-space, 5.0 kW/m2

. 

Figure 38. Response of all type T thermocouples, fabric-exposed-space, 1.2 kW/m2

. 

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0.81 mm

0.51 mm

0.26 mm

0.13 mm

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0.13 mm

0.81 mm

0.51 mm

0.26 mm
 46 

Figure 39. Response of all type T thermocouples, fabric-exposed-space, 5.0 kW/m2

. 

Figure 40. Response of all type J thermocouples, fabric-substrate-no space, 1.2 kW/m2

. 

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0.81 mm

0.51 mm

0.26 mm

0.13 mm
 47 

Figure 41. Response of 0.13 mm, 0.26 mm, and 0.51 mm type J thermocouples, fabric-substrateno space, 5.0 kW/m2

. No data for 0.81 mm type J thermocouple. 

Figure 42. Response of all type K thermocouples, fabric-substrate-no space, 1.2 kW/m2

. 

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0.51 mm

0.26 mm

0.13 mm
 48 

Figure 43. Response of all type K thermocouples, fabric-substrate-no space, 5.0 kW/m2

. 

Figure 44. Response of all type T thermocouples, fabric-substrate-no space, 1.2 kW/m2

. 

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0.82 mm

0.51 mm

0.26 mm

0.13 mm
 49 

Figure 45. Response of all type T thermocouples, fabric-substrate-no space, 5.0 kW/m2

. 

Figure 46. Response of all type J thermocouples, fabric-substrate-space, 1.2 kW/m2

. 

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0.81 mm

0.51 mm

0.26 mm

0.13 mm
 50 

Figure 47. Response of 0.13 mm, 0.26 mm, and 0.51 mm type J thermocouples, fabric-substratespace, 5.0 kW/m2

. No data for 0.81 mm type J thermocouple. 

Figure 48. Response of all type K thermocouples, fabric-substrate-space, 1.2 kW/m2

. 

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0.51 mm

0.26 mm

0.13 mm
 51 

Figure 49. Response of all type K thermocouples, fabric-substrate-space, 5.0 kW/m2

. 

Figure 50. Response of all type T thermocouples, fabric-substrate-space, 1.2 kW/m2

. 

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0.13 mm
 52 

Figure 51. Response of all type T thermocouples, fabric-substrate-space, 5.0 kW/m2

. 

Figure 52. Response of type J, K, and T thermocouples, 0.13 mm wire diameter, exposed, 1.2 

kW/m2. 

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

Type J

Type K

Type T

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0.81 mm

0.51 mm

0.26 mm

0.13 mm
 53 

Figure 53. Response of type J, K, and T thermocouples, 0.13 mm wire diameter, exposed, 5.0 

kW/m2

. 

Figure 54. Response of type J, K, and T thermocouples, 0.81 mm wire diameter, exposed, 1.2 

kW/m2

. 

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

Type J

Type K

Type T

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

Type J

Type K

Type T

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)
 54 

Figure 55. Response of type J, K, and T thermocouples, 0.81 mm wire diameter, exposed, 5.0 

kW/m2

. 

Figure 56. Response of type J, K, and T thermocouples, 0.13 mm wire diameter, substrate, 1.2 

kW/m2. 

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

Type J

Type K

Type T
 55 

Figure 57. Response of type J, K, and T thermocouples, 0.13 mm wire diameter, substrate, 5.0 

kW/m2

. 

Figure 58. Response of type J, K, and T thermocouples, 0.81 mm wire diameter, substrate, 1.2 

kW/m2. 

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

Type J

Type K

Type T

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

Type K

Type J

Type T
 56 

Figure 59. Response of type J, K, and T thermocouples, 0.81 mm wire diameter, substrate 5.0 

kW/m2

. 

Figure 60. Response of type J, K, and T thermocouples, 0.13 mm wire diameter, fabric-exposedno space, 1.2 kW/m2

. 

0

5

10

15

20

25

30

35

40

45

50

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

Type J

Type K

Type T

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

Type J

Type K

Type T
 57 

Figure 61. Response of type J, K, and T thermocouples, 0.13 mm wire diameter, fabric-exposedno space, 5.0 kW/m2

. 

Figure 62. Response of type J, K, and T thermocouples, 0.81 mm wire diameter, fabric-exposedno space, 1.2 kW/m2

. 

0

5

10

15

20

25

30

35

40

45

50

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

Type J

Type K

Type T

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

Type J

Type K

Type T
 58 

Figure 63. Response of type J, K, and T thermocouples, 0.81 mm wire diameter, fabric-exposedno space, 5.0 kW/m2

. 

Figure 64. Response of type J, K, and T thermocouples, 0.13 mm wire diameter, fabric-exposedspace, 1.2 kW/m2

. 

0

5

10

15

20

25

30

35

40

45

50

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0

5

10

15

20

25

30

35

40

45

50

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

Type J

Type K

Type T
 59 

Figure 65. Response of type J, K, and T thermocouples, 0.13 mm wire diameter, fabric-exposedspace, 5.0 kW/m2

. 

Figure 66. Response of type J, K, and T thermocouples, 0.81 mm wire diameter, fabric-exposedspace, 1.2 kW/m2

. 

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

Type J

Type K

Type T

0

5

10

15

20

25

30

35

40

45

50

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

Type J

Type K

Type T
 60 

Figure 67. Response of type J, K, and T thermocouples, 0.81 mm wire diameter, fabric-exposedspace, 5.0 kW/m2

. 

Figure 68. Response of type J, K, and T thermocouples, 0.13 mm wire diameter, fabricsubstrate-no space, 1,25 kW/m2

. 

0

5

10

15

20

25

30

35

40

45

50

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

Type T

0

5

10

15

20

25

30

35

40

45

50

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

Type J

Type K

Type T
 61 

Figure 69. Response of type J, K, and T thermocouples, 0.13 mm wire diameter, fabricsubstrate-no space, 5.0 kW/m2

. 

Figure 70. Response of type J, K, and T thermocouples, 0.81 mm wire diameter, fabricsubstrate-no space, 1.2 kW/m2

. 

0

5

10

15

20

25

30

35

40

45

50

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

Type J

Type K

Type T

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

Type T
 62 

Figure 71. Response of type K, and T thermocouples, 0.81 mm wire diameter, fabric-substrateno space, 5.0 kW/m2

. No data for type J thermocouple. 

Figure 72. Response of type J, K, and T thermocouples, 0.13 mm wire diameter, fabricsubstrate-space, 1.2 kW/m2

. 

0

5

10

15

20

25

30

35

40

45

50

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

Type K

Type T
 63 

Figure 73. Response of type J, K, and T thermocouples, 0.13 mm wire diameter, fabricsubstrate-space, 5.0 kW/m2

. 

Figure 74. Response of type J, K, and T thermocouples, 0.81 mm wire diameter, fabricsubstrate-space, 1.2 kW/m2

. 

0

5

10

15

20

25

30

35

40

45

50

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

Type J

Type K

Type T

0

5

10

15

20

25

30

35

40

45

50

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

Type J

Type K

Type T
 64 

Figure 75. Response of type K, and T thermocouples, 0.81 mm wire diameter, fabric-substratespace, 5.0 kW/m2

. No data for type J thermocouple 

Figure 76. Response of encapsulated type T thermocouple, exposed, all three heat flux levels, 

with error bars. 

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

1.2 kW/m2

2.5 kW/m2

5.0 kW/m2

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

Type K

Type T
 65 

Figure 77. Response of encapsulated type T thermocouple, substrate, all three heat flux levels, 

with error bars. 

Figure 78. Response of encapsulated type T thermocouple, fabric-exposed-no space, all three 

heat flux levels, with error bars. 

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

1.2 kW/m2

2.5 kW/m2

5.0 kW/m2

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

1.2 kW/m2

2.5 kW/m2

5.0 kW/m2
 66 

Figure 79. Response of encapsulated type T thermocouple, fabric-exposed-space, all three heat 

flux levels, with error bars. 

Figure 80. Response of encapsulated type T thermocouple, fabric-substrate-no space, all three 

heat flux levels, with error bars. 

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

1.2 kW/m2

2.5 kW/m2

5.0 kW/m2

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

1.2 kW/m2

2.5 kW/m2

5.0 kW/m2
 67 

Figure 81. Response of encapsulated type T thermocouple, fabric-substrate-space, all three heat 

flux levels, with error bars. 

Figure 82. Response of copper disk with 4 type J thermocouples, exposed, all three heat flux 

levels, with error bars. 

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

1.2 kW/m2

2.5 kW/m2

5.0 kW/m2 

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

1.2 kW/m2

2.5 kW/m2

5.0 kW/m2
 68 

Figure 83. Response of copper disk with 4 type J thermocouples, substrate, all three heat flux 

levels, with error bars. 

Figure 84. Response of copper disk with 4 type J thermocouples, fabric-exposed-no space, all 

three heat flux levels, with error bars. 

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

1.2 kW/m2

2.5 kW/m2

5.0 kW/m2 

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

1.2 kW/m2

2.5 kW/m2

5.0 kW/m2 
 69 

Figure 85. Response of copper disk with 4 type J thermocouples, fabric-exposed-space, all three 

heat flux levels, with error bars. 

Figure 86. Response of copper disk with 4 type J thermocouples, fabric-substrate-no space, all 

three heat flux levels, with error bars. 

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

1.2 kW/m2

2.5 kW/m2

5.0 kW/m2

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

1.2 kW/m2

2.5 kW/m2

5.0 kW/m2
 70 

Figure 87. Response of copper disk with 4 type J thermocouples, fabric-substrate-space, all three 

heat flux levels, with error bars. 

Figure 88. Response of copper disk with 1 type J thermocouple, exposed, all three heat flux 

levels, with error bars. 

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

1.2 kW/m2

2.5 kW/m2

5.0 kW/m2

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

1.2 kW/m2

2.5 kW/m2

5.0 kW/m2
 71 

Figure 89. Response of copper disk with 1 type J thermocouple, substrate, all three heat flux 

levels, with error bars. 

Figure 90. Response of thin film heat flux gauge, exposed, all three heat flux levels, with error 

bars. 

0

1

2

3

4

5

6

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Heat Flux (kW/m2

)

1.2 kW/m2

2.5 kW/m2

5.0 kW/m2

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Temperature Increase (oC)

1.2 kW/m2

2.5 kW/m2

5.0 kW/m2
 72 

Figure 91. Response of thin film heat flux gauge, substrate, all three heat flux levels, with error 

bars. 

Figure 92. Response of thin film heat flux gauge, fabric-exposed-no space, all three heat flux 

levels, with error bars. 

0

1

2

3

4

5

6

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Heat Flux (kW/m2

)

1.2 kW/m2

2.5 kW/m2

5.0 kW/m2

0

1

2

3

4

5

6

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Heat Flux (kW/m2

)

1.2 kW/m2

2.5 kW/m2

5.0 kW/m2
 73 

Figure 93. Response of thin film heat flux gauge, fabric-exposed-space, all three heat flux 

levels, with error bars. 

Figure 94. Response of thin film heat flux gauge, fabric-substrate-no space, all three heat flux 

levels, with error bars. 

0

1

2

3

4

5

6

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Heat Flux (kW/m2

)

1.2 kW/m2

2.5 kW/m2

5.0 kW/m2

0

1

2

3

4

5

6

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Heat Flux (kW/m2

)

1.2 kW/m2

2.5 kW/m2

5.0 kW/m2
 74 

Figure 95. Response of thin film heat flux gauge, fabric-substrate-space, all three heat flux 

levels, with error bars. 

Figure 96. Response of Schmidt-Boelter total heat flux gauge, exposed, all three heat flux levels, 

with error bars. 

0

1

2

3

4

5

6

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Heat Flux (kW/m2

)

1.2 kW/m2

2.5 kW/m2

5.0 kW/m2

0

1

2

3

4

5

6

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Heat Flux (kW/m2

)

1.2 kW/m2

2.5 kW/m2

5.0 kW/m2
 75 

Figure 97. Response of Schmidt-Boelter total heat flux gauge, fabric-exposed-no space- two 

heat flux levels, with error bars. 

Figure 98. Response of Schmidt-Boelter total heat flux gauge, fabric-exposed-space, two heat 

flux levels, with error bars. 

0

1

2

3

4

5

6

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Heat Flux (kW/m2

)

1.2 kW/m2

2.5 kW/m2

0

1

2

3

4

5

6

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Heat Flux (kW/m2

)

1.2 kW/m2

2.5 kW/m2
 76 

Figure 99. Response of Schmidt-Boelter total heat flux gauge, fabric-substrate-no space, two 

heat flux levels, with error bars. 

Figure 100. Response of Schmidt-Boelter total heat flux gauge, fabric-substrate-space, two heat 

flux levels, with error bars. 

0

1

2

3

4

5

6

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Heat Flux (kW/m2

)

1.2 kW/m2

2.5 kW/m2

0

1

2

3

4

5

6

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Heat Flux (kW/m2

)

1.2 kW/m2

2.5 kW/m2
 77 

Figure 101. Response of sapphire window radiometer, exposed, all three heat flux levels, with 

error bars. 

Figure 102. Response of sapphire window radiometer, fabric-exposed-no space, two heat flux 

levels, with error bars. 

0

1

2

3

4

5

6

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Heat Flux (kW/m2

)

1.2 kW/m2

2.5 kw/m2

0

1

2

3

4

5

6

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Heat Flux (kW/m2

)

1.2 kW/m2

2.5 kW/m2

5.0 kW/m2
 78 

Figure 103. Response of sapphire window radiometer, fabric-exposed-space, two heat flux 

levels, with error bars. 

Figure 104. Response of sapphire window radiometer, fabric-substrate-no space, two heat flux 

levels, with error bars. 

0

1

2

3

4

5

6

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Heat Flux (kW/m2

)

1.2 kW/m2

2.5 kW/m2

0

1

2

3

4

5

6

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Heat Flux (kW/m2

)

1.2 kW/m2

2.5 kW/m2
 79 

Figure 105. Response of sapphire window radiometer, fabric-substrate-space, two heat flux 

levels, with error bars. 

Figure 106. Response of zinc selenide window radiometer, exposed, all three heat flux levels 

with error bars. 

0

1

2

3

4

5

6

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Heat Flux (kW/m2

)

1.2 kW/m2

2.5 kW/m2

5.0 kW/m2

0

1

2

3

4

5

6

0 60 120 180 240 300 360 420 480 540 600 660

Time (s)

Heat Flux (kW/m2

)

1.2 kW/m2

2.5 kW/m2
 80 

 

1 National Fire Protection Association, “National Fire Protection Association 1971 Standard on 

Protective Ensemble for Structural Fire Fighting,” 2000 Edition, National Fire Protection 

Association, Quincy, MA 02269. 

2 Lawson, R. L., “Fire Fighter’s Protective Clothing and Thermal Environments of Structural 

Fire Fighting,” NISTIR 5804. National Institute of Standards and Technology, 

Gaithersburg, MD, August 1996. 

3 Foster, J. A., and Roberts, G. V., “Measurements of the Firefighting Environment – Summary 

Report,” Fire Engineers Journal. Vol. 55, No. 178, September 1995, pp 30-34. 

4 Abbott, N. J., and Schulman, S., “Protection from Fire: Non Flammable Fabrics and 

Coatings,” Fire Retardants: Proceedings of 1976 International Symposium on 

Flammability and Fire Retardants, May 6-7, 1976, pp 64-80. 

5 Henriques, F.C., and Moritz, A. R., “Studies of Thermal Injury: I. The Conduction of Heat to 

and Through Skin and the Temperatures Attained Therein. A Theoretical and an 

Experimental Investigation,” American Journal of Pathology, Vol. 23, p. 531, 1947. 

6 Stoll, A. M., and Greene, L.C., “Relationship Between Pain and Tissue Damage Due to 

Thermal Radiation,” Journal of Applied Physiology, Vol. 14, pp 373, 1959. 

7 Chianta, B. A., and Stoll, A. M., “Heat Transfer in Protection From Flames,” Aerospace 

Medicine, Vol. 34, p 7-11, January 1964. 

8 Barker, R. L., Hamouda, H., Shalev, I., and Johnson, J., “Review and Evaluation of Thermal 

Sensors for use in Testing Fire Fighters Protective Clothing,” NIST GCR 99-773, 

National Institute of Standards and Technology, Gaithersburg, MD 20899, March 1999. 

9 Dale, J. D., Crown, E. M., Ackerman, M. Y., Leung, E., Rigakis, K. B., “Instrumented 

Mannequin Evaluation of Thermal Protective Clothing,” Performance of Protective 

Clothing: Fourth Volume, ASTM STP 1133, ASTM Philadelphia 1992. 

10 Vettori, R. L., “Effect of an Obstructed Ceiling on the Activation Time of a Residential 

Sprinkler,” NISTIR 6253, National Institute of Standards and Technology, Gaithersburg, 

MD 20899, November 1998. 

11 Lawson, J. R., and Twilley, W. H., “Development of an Apparatus for Measuring the 

Thermal Performance of Fire Fighter’s Protective Clothing,” NISTIR 6400, National 

Institute of Standards and Technology, Gaithersburg, MD 20899, October 1999. 

12 American Society for Testing and Materials, “E162 Standard Test Method for Surface 

Flammability of Materials Using a Radiant Heat Energy Source,” Annual Book of ASTM 

Standards, Vol. 04.07, West Conshohocken, PA, 1997. 

13 American Society for Testing and Materials, “E1321 Standard Test Method for Determining 

Material Ignition and Flame Spread Properties,” Annual Book of ASTM Standards, Vol. 

04.07, West Conshohocken, PA, 1997. 

14 McGuire, J., H., “Heat Transfer by Radiation,” Department of Scientific and Industrial 

Research and Fire Offices Committee, London, 1953. 

15 Incropera, F. P., and Dewitt, D. P., “Fundamentals of Heat and Mass Transfer Fourth 

Edition,” John Wiley and Sons, New York, NY, 1996. 

11.0 References 
 81 

 

16 Taylor, B.N., Kuyatt, C. E., “Guidelines for Evaluating and Expressing the Uncertainty of 

NIST Measurements Results,” NIST Technical Note 1291, National Institute of 

Standards and Technology, Gaithersburg, MD 20899, 1994. 

17 American Society for Testing and Materials “Manual on the Use of Thermocouples in 

Temperature Measurement Fourth Edition,” ASTM, 1916 Race Street, Philadelphia, PA 

19103, 1993. 

18 Lawson, J. R., Pinder, T. A., “Estimates of Thermal Conductivity for Materials used in Fire 

Fighter’s Protective Clothing,” NISTIR 6512, National Institute of Standards and 

Technology, Gaithersburg, MD 20899, May 2000. 

19 Stoll, A. M., and Hardy, J. D., “Direct Experimental Comparison of Several Surface 

Temperature Measuring Devices,” Review of Scientific Instruments, Vol. 20 No. 9 

September 1949. 

20 American Society for Testing and Materials, “E-457 Standard Test Method for Measuring 

Heat Transfer Rate Using a Thermal Capacitance (Slug) Calorimeter,” Annual Book of 

ASTM Standards, Vol. 04.07, West Conshohocken, PA, 1997.