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FIRE TESTING
BG&S regularly employs fire testing of various products and assemblies to develop needed modeling data. In some cases, if merited, we will perform full scale fire tests of the involved compartment or fuel array packages as a means of exploring the viability of various theories put forth in any particular case. We frequently also perform small, medium and large scale fire testing to assist in failure analysis or for purposes of fire research. Fire testing can provide critically important data to the fire scientist and fire investigator that cannot be derived in any other way. Testing also provides a platform for meaningful material behavior analyses where variables such as fuel package configurations and arrays, ventilation conditions, and thermal inertia effects are of interest.
Small scale testing, also referred to as bench scale testing, can show how a small-sized material specimen reacts to various failure modes and/or incipient fire situations. Flammability and fire retardancy on a comparative basis may be of interest, or conformance with specific ASTM testing requirements. Medium and large scale testing, however, may be warranted for data development. With the use of sophisticated data acquisition systems and equipment involving radiometers, thermocouples, infrared thermal imaging cameras, oxygen depletion sensors, Intermediate Scale Calorimeters (ICAL) and other similar devices, BG&S can provide the needed foundational basis for applying the scientific method in the investigative process as called for by NFPA 921.
Large scale and full scale fire testing typically involves recreating an entire section of the subject occupancy or involved structure – sometimes one room (compartment) will suffice or sometimes it may be necessary to recreate an entire commercial kitchen or residential house. This process depends on the extent to which pre-fire conditions can be established, such as materials of construction, construction details, ventilation provisions, furnishings, interior finish details, etc. Large scale testing may also involve entire pieces of heavy equipment, automobiles, aircraft, watercraft, or other motorized or non-motorized pieces of machinery. Large-scale testing may employ an established ASTM test method, such as ASTM E-84, the Example of Thermal Imaging (Thermography) of a Slipping Pulley Belt (BG&S).
Steiner Tunnel Test for evaluating surface flame spread, or ASTM E-119, the standard test method used to rate fire-resistive assemblies, such as 1hour and 2 hour fire walls, by exposing the test assembly to predetermined thermal impact based on a standard fire time-temperature fire curve.
Compartment and room fire testing is typically completed under a large calorimeter hood where the effluent from the burning assembly is collected and analyzed while fire progress is documented with video and photographs. The heat release data collected can then be used as input data for a computer fire modeling. Use of mass loss techniques for calculating heat release rates can also be employed during fire testing under the calorimeter hood and/or at large outdoor test facilities. BG&S has successfully built and tested entire homes and/or portions of large structures inside a fire test laboratory. In all cases the test compartments are fitted with identical or substantially similar materials and furnishings as were present in the subject structure under investigation. After construction, the test compartments are outfitted with a variety of data collection equipment and video cameras along with other case specific sensing equipment. In this manner it is possible to explore numerous hypotheses using the same test structure after slight remodeling following each fire test.
In past BG&S cases, fire testing has provided conclusive visual evidence to support or refute percipient witness testimony, to illustrate specific fire behavior under defined conditions, to corroborate or rebut alleged fire pattern analyses, and substantiate or disprove conclusions based on vector analysis and char-depth determinations. Fire test results can be used for making a compelling comparison analysis with evidence from the actual fire scene and the output from computer simulations. Further, video footage and still photographs provide powerful tools for courtroom presentations and provide the jury with an understandable comparison to actual scene photographs taken by witnesses, fire departments, police departments, and other fire investigators.
BG&S works with a variety of certified laboratories, such as Western Fire Center, Inc., to conduct fire testing. Dean Bundy sits on the ASTM E-5 fire test committee and has an active role in participating in standards development and revision. BG&S experts are available to assist you with analyzing your specific fire or explosion incident and aid you in determining if fire testing of any scale may provide you with important information necessary for proper analysis of origin, cause, and contributory damages issues, and to ensure the best presentation of your case before the jury.
Further information on Fire Modeling, Fire Testing, and how they relate to fire investigation may be found at the National Institute’s (NIST) Fire Research homepage: http://www.fire.nist.gov
Examples of the application of the Fire Dynamics Simulator (FDS) model and its capability can be found at: http://www.fire.nist.gov/fds/index.html
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