FPEeXTRA Issue 63

The NIST Fire Calorimetry Database: A Resource for Fire Protection Engineers

By Matthew Bundy, PhD

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Fire size, growth rate and smoke production rate resulting from real burning materials is important to practicing fire protection engineers and scientists. The size of a fire, quantified as the heat release rate (HRR), is usually measured in kilowatts (kW). There are many ways to determine fire size, but one versatile and accurate method is to capture all of the products of combustion from a fire using a canopy style exhaust hood and measure the amount of oxygen the fire consumes. This method is based on the observation that for a wide range of combustible materials, the thermal energy produced by a fire is proportional to the mass of oxygen it consumes [1]. Oxygen consumption calorimetry is now widely adopted as a tool for studying fires and developing materials with improved fire performance [2]. Bench scale devices such as the cone calorimeter (ASTM 1354 and ISO 5660) and large open-canopy calorimeters (ASTM 2067, ISO 9705 and ISO 24473) use this methodology.

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     Figure 1: Schematic drawing of large-scale oxygen consumption calorimeter [4].

The National Fire Research Laboratory (NFRL) located at the National Institute of Standards and Technology (NIST) in Gaithersburg, MD [3] has four fire calorimeters and can conduct calorimetry measurements for fires up to 20,000 kW and study the effects of fire on multi-story structures. The laboratory, exhaust hoods, instrumentation, measurement methods and uncertainty analysis are described in detail by Bryant and Bundy [4].

The NIST Fire Calorimetry Database (FCD) [5], launched in December of 2020, is an online public resource containing the results of fire experiments conducted at the NFRL. The FCD contains experiments ranging in scale from small single items to fully furnished rooms. Each experiment contains detailed documentation about methodology and uncertainty as described in a peer reviewed report. The initial published data set consists of data augmented video, images, plots and tabulated data from more than 180 experiments.  An additional 200 experiments from ongoing projects are ready for publication pending review and the database is expected to grow each year. Each experiment is described with metadata, and time dependent calculations based on dozens of measurement sensors and input parameters each with quantified uncertainty.

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Figure 2: Snapshot from a video in the database showing the flashover of a furnished room 6 minutes after ignition [6].

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Figure 3. Sample data plots for room flashover test with annotated event markers.  1-Ignition, 2-Flashover, 3-Start water hose suppression 4-Fire Out 5-Room cleared [6].

The NIST FCD has several potential uses. In addition to the heat release rate, the database provides other fire properties such as the yields of soot and carbon monoxide. It can be used to select “design fires” as input for advanced predictive models or simple engineering calculations. Computational field models or zone models may require prescribed burning rates for a given application, and there is limited data available on real burning items. This data can be used to develop materials with improved fire performance. The NIST FCD has proven a useful tool for researchers in planning future experiments and sharing results with stakeholders.

The database contains several unique features.  The user can sort and browse through a list of projects and experiments or use the search box to find experiments based on a description of the fuel type, specimen, or test description. Each experiment can be viewed in a time-compressed high-resolution video augmented with data and time stamps. The video playback is compressed for easy viewing, typically less than 1 min in length. At the peak heat release rate, each video is shown in real time for a prescribed period, usually 5 s to 10 s.  Each event during an experiment is marked with a timestamp and a video image snapshot is provided in a table. All video, plots images, event snapshot images, and comma separated value (CSV) data files are available for download.  

Figure 4.  Snapshot from video of confirmation experiment with natural gas tube burner, showing the agreement between two independent methods (fuel consumption and oxygen consumption) of determining heat release rate. [5]

The research conducted at the NFRL has a wide range of objectives. These include the study of fire performance of materials, validation of predictive models, post fire investigations, development of new fire metrology, development of fire codes or standards, or studying structural fire resistance. The results of these studies reach the project stakeholders; however, they may also have value beyond the intended objective and audience.  For example, someone may be interested in the relationship between flame height and burning rate for a wide range of fuels and configurations available from unrelated projects.  

Open access data is becoming more prevalent and some journals are encouraging authors to publish raw data to support research articles.  Heat release rate data available to the public is limited [7,8] and can be difficult to discover and access. The NIST FCD can serve as a model for other institutions to make valuable fire data available to the fire safety community. 

Matthew Bundy, PhD is with NIST

 

REFERENCES:

  1. Huggett C. Estimation of Rate of Heat Release by Means of Oxygen Consumption Measurements. Fire Mater 4:61–65 (1980) https://doi.org/10.1002/fam.810040202
  2. Beyler, C., Croce, P., Dubay, C. et al. Oxygen consumption calorimetry, William Parker: 2016 DiNenno Prize. Fire Sci Rev 6, 1 (2017). https://doi.org/10.1186/s40038-016-0016-z
  3. Bundy, M., Hamins, A., Gross, J., Grosshandler, W., Choe, L., Structural Fire Experimental Capabilities at the NIST National Fire Research Laboratory. Fire Tech. 52. (2016) https://doi.org/10.1007/s10694-015-0544-4
  4. Bryant, R. and Bundy, M. The NIST 20 MW Calorimetry Measurement System for Large-Fire Research, NIST Technical Note 2077, (2019) https://doi.org/10.6028/NIST.TN.2077
  5. NIST Fire Calorimetry Database (2021) https://doi.org/10.18434/mds2-2314
  6. M. Zammarano, MS. Hoehler, JR. Shields, AL. Thompson, I. Kim, IT. Leventon and MF. Bundy, Full-Scale Experiments to Demonstrate Flammability Risk of Residential Upholstered Furniture and Mitigation Using Barrier Fabric, NIST Technical Note 2129, (2020) https://doi.org/10.6028/NIST.TN.2129
  7. University of Maryland Burning Item Database http://www.firebid.umd.edu/burning-item-database.php
  8. Babrauskas, Heat Release Rates pp.799-904. SFPE Handbook of Fire Protection Engineering, fifth edition (2016) https://doi.org/10.1007/978-1-4939-2565-0_26

Matthew Bundy is with NIST