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User’s Guide for Fire Calorimetry Database (FCD)

Revised 10/23/2020, M. Bundy

1) Overview the Fire Calorimetry Database (FCD)

The Fire Calorimetry Database (FCD) contains compilation of fire experiments conducted at the 

NIST National Fire Research Laboratory (NFRL). The FCD contains a summary data page for 

each fire experiment. The basic test information is given in Table 1. If available, a time 

compressed video of the fire with heat release rate data overlay is provided. The time series data 

collected during the test is provided in comma separated values (.csv) files at 1 second time 

intervals. Table 2 of the experiment data page shows a summary of test measurement results. 

Table 3 provides a summary of input parameters used in the calorimetry calculations. Time 

series plots of the heat release rate and combustion products species are shown for each test and 

include markers for annotated events during the test. A snapshot image from the test video is 

provided for each event. Each test has a minimum of two events for “ignition” and “fire out”. 

The database is organized into projects and can searched by keywords or sorted by selected 

fields such as fuel type or total heat release.

2) Guide for referencing the FCD data

There are multiple citations for experiments contained in this database. Each project has at least 

one report or journal article that describes the test methods, results and conclusions of the study. 

This reference should be cited when referring to experiments from a single project. The NIST 

Technical Note 2077 [1] should be cited when referencing the calorimetry methods or 

uncertainty analysis in this database. Finally, the NIST Fire Calorimetry Database [2] should be 

cited when using video, images, or data files or summary calculations found here.

3) Description of FCD calculations

The generation rates of energy and combustion products are calculated over the time period from 

ignition (tign) to fire out (tout). These two events are marked electronically in the data file and are 

required in order to generate the standard report. The total amount of heat generated by the fire 

is:

Total Heat Release (THR) = ∑ Q̇

oc(t) ∆t

tout

t=tign

where Q̇

oc(t) is the heat release rate (HRR) determined by oxygen consumption calorimetry at 

time t and defined by Equation 2 in TN2077 [1]. The total amounts of product species and the 

total amount of oxygen consumed are given by:

Total CO2 =

MCO2

Mair

∑ [XCO2

(t) − XCO2

o

]

tout

t=tign

ṁ e ∆t
2

Total CO =

MCO

Mair

∑ [XCO(t) − XCO

o

]

tout

t=tign

ṁ e ∆t

Total O2 =

MO2

Mair

∑ [XO2

o − XO2

(t)]

tout

t=tign

ṁ e ∆t

where

ṁ e = mass flow rate in exhaust duct, kg/s

Mi = molecular weight of gas i, kg/kmole

Xi = volume fraction of exhaust gas i, L/L

Xi

o = volume fraction of ambient gas i, L/L

The mass of fuel consumed by the fire, ∆mfuel, can be estimated by two different methods: (1) a

load cell measures the mass of the specimen before, mfuel,i, and after, mfuel,f, the test; or (2) the 

measured total heat release (THR) is divided by an assumed (i.e. literature value) fuel heat of 

combustion. If both fuel consumption measurements are available, the value used to calculate

species yields is the one with lower uncertainty. If the load cell measurement of fuel mass loss is 

available, the heat of combustion can be estimated as follows:

Net Effective Heat of Combustion = HOCfuel,eff =

THR

∆mfuel

The species yields are given by the following expressions:

CO2 Yield = yCO2 =

Total CO2

∆mfuel

CO Yield = yCO =

Total CO

∆mfuel

O2 Yield = yO2 =

Total O2

∆mfuel

The smoke particulate generated by the fire is measured via the light extinction of a HeNe laser 

beam across the center of the exhaust duct. The measurement method is described by 

Mulholland et al [3]. The intensity of the signal of the Si photodiode detector at time t is given 

by I(t). The background intensity, I

o

, is the mean intensity over a 60 s period before ignition.

The light extinction coefficient, K, is defined:
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K(t) =

1

Deff

ln

I

o

I(t)

where Deff is the effective duct diameter. The total amount of particulate (i.e. soot) matter 

generated by the fire is:

Total Soot =

A

σs

∑ K(t) Veff(t) ∆t

tout

t=tign

where A is the cross sectional area of the duct, Veff(t) is the effective velocity of the effluent, 

and σsis the specific extinction coefficient, which is assumed to be 8700 m2/kg unless otherwise 

specified. The soot yield of the fire, averaged over the entire burn, is:

Soot Yield = ysoot =

Total Soot

∆mfuel

The uncertainty values given in Table 2 are based on a propagation of uncertainty from the input 

parameters in Table 3 and uncertainty estimates determined as described in TN 2077. Figure 15 

of TN 2077 provides the results of a linear regression of the data for expanded relative 

uncertainty of the heat release rate measurement. Uncertainty estimates are computed using

empirical formulas such as the one below (Q̇

OC = [MW]), an example case of the 3 MW hood 

with a generic combustible fuel.

UQ̇OC(t)

Q̇

OC(t)

= 0.0683 Q̇

OC(t)

−0.028

Estimates of uncertainty of the burner heat release rate are computed from the results of the 

linear regression provided in Figure 18 of TN 2077.

Total heat released is a summation of measurements made by the same instrument, therefore 

each measurement, Q̇

OC(t), is correlated. The uncertainty of a summation of correlated 

measurements is the summation of the uncertainties, whenever the correlation coefficient is 

unity, r(i,j) = 1.0. Therefore, the uncertainty of the total heat release is given as:

UTHR = ∑ UQ̇OC(t)

tout

t=tign

∆t

The standard deviation of each of the measurement components was calculated for the 

background measurement period of 60 s during ambient air conditions before the fire was 

ignited. If the measured values were less than 10 times the background standard deviation the 

background standard deviation was added to the uncertainty to provide a conservative estimate. 

This is necessary because the regression analysis in Figure 15 does not include low values of 

heat release. The same method is applied to the calculation of combustion species yields. 
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Not all measurements are performed for each test. Missing values are shown as “Not measured” 

in the summary of test results table. If the measurement value in table 2 is less than 3 times the 

standard measurement uncertainty the value is displays as “below detection limit”. 

References

[1] Bryant, R. and Bundy, M. The NIST 20 MW Calorimetry Measurement System for 

Large-Fire Research, Technical Note (NIST TN) 2077, 2019 

https://doi.org/10.6028/NIST.TN.2077

[2] NIST Fire Calorimetry Database https://doi.org/10.18434/mds2-2314

[3] Mulholland, G, Johnsson, E, Fernandez, M, Shear, D (2000) Design and Testing of a 

New Smoke Concentration. Fire and Materials. 24, 231-243