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Engineering Laboratory / Fire Research Division

National Fire Research Laboratory

Test_33

Table 1. Test Information
Name
Test_33
Date
Description

Low voltage switchgear cabinet w/ 100kW natural gas burner below the left breaker. Water cooled camera pointed at burner.
Specimen
Box Burner
Ignition
pilot flame
Project ID (s)
NRC Electrical Cabinet Experiments
Test Director
McGrattan

Timelapse Video with Heat Release Rate Plot

Table 2. Summary of Test Results
Measurement Value Uc Unit
Peak Heat Release Rate, PHRR
349
19
kW
Time to Peak Heat Release Rate
10.93
0.07
min
Total Heat Released, THR
460
29
MJ
Gas Burner Total Heat Released, NGTHR
52.19
0.74
MJ
Heat Release Quality Confirmation, HRQC
 Not measured -
MJ/MJ
Net Specimen Mass (gravimetric), NM = Mi-Mf
 Not measured -
kg
Total Fuel Mass Burned, TFM = THR / HOCf
9.19
0.65
kg
Net Effective Heat of Combustion = THR / NM
 Not measured -
MJ/kg
O2 Yield = O2 Consumed / TFM
3.80
0.29
kg/kg
CO2 Yield = CO2 Generated / TFM
3.82
0.30
kg/kg
CO Yield = CO Generated / TFM
0.237
0.019
kg/kg
Soot Yield = Soot Generated / TFM
0.105
0.021
kg/kg
Baseline Hood Exhaust Flow
12.91
0.39
kg/s
Test Duration = Time(Fire Out) - Time(Ignition)
78.58
0.03
min

Uc = Combined Expanded Uncertainty with 95% confidence level

Table 3. Summary of Test Input Parameters
Parameter Value Uc Unit
Fuel Type
Natural Gas
 - -
Hood Size
6
 -
m
Effective Duct Diameter
1.975
0.005
m
Exhaust Flow Correction Factor
1.055
0.034
 -
Net Heat of Combustion (per unit mass O2), Ef
12.54
0.50
MJ/kg
Net Heat of Combustion(per unit mass fuel), HOCf
50.00
1.50
MJ/kg
Initial Specimen Mass, Mi (gravimetric)
 Not measured -
kg
Final Specimen Mass, Mf (gravimetric)
 Not measured -
kg
Plot of Fire Heat Release Rate with event markers. Uncertainty bar shown at peak value.
Figure 1. Plot of Heat Release Rate data with event markers and error bars shown at peak.
Table 4. Summary of Observed Test Events
Event Time (min) Description Video Snapshot Image
1
0.00
Ignition
Ignition
2
9.33
100 kW to 50 kW
100 kW to 50 kW
3
10.62
Gas Burner OFF
Gas Burner OFF
peak
10.93
Peak HRR
Peak HRR
4
17.20
Hood Flow: from 12 kg/s to 20 kg/s
Hood Flow: from 12 kg/s to 20 kg/s
5
17.88
spread to upper cabinet
spread to upper cabinet
6
38.47
upper right panel melted
upper right panel melted
7
75.00
clock failure
clock failure
8
75.63
water suppression
water suppression
9
78.58
Fire Out
Fire Out

Table 5. Supplemental Data Plots

Plot of Oxygen Dry Volume Fraction in hood exhaust stream.
Plot of Oxygen Dry Volume Fraction in hood exhaust stream.
Plot of Carbon Dioxide Dry Volume Fraction in hood exhaust stream.
Plot of Carbon Dioxide Dry Volume Fraction in hood exhaust stream.
Plot of Carbon Monoxide Dry Volume Fraction in hood exhaust stream.
Plot of Carbon Monoxide Dry Volume Fraction in hood exhaust stream.
Plot of Radiant Heat Flux data with event markers. r= radial distance from center of hood, h=height above floor.
Plot of Radiant Heat Flux data with event markers. r= radial distance from center of hood, h=height above floor.
Plot of Smoke Laser Extinction Coefficient in hood exhaust stream.
Plot of Smoke Laser Extinction Coefficient in hood exhaust stream.
Plot of Exhaust Duct Mass Flow Rate.
Plot of Exhaust Duct Mass Flow Rate.

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

NIST Fire Calorimetry Database (FCD)
https://doi.org/10.18434/mds2-2314

Report Process Script Version
NFRL_Report_8.5.9
Last Updated January 17, 2025