Analysis of Post-Fire Characteristics of Portable Oil Filled Room Heaters

Analysis of Post-Fire Characteristics of Portable Oil Filled Room Heaters to Determine Pre-Fire Orientation

K. Scott Barnhill, PE
Investigative Forensic Specialists, PLLC

Presented at the International Symposium on Fire Investigation Science and Technology, 2014

ABSTRACT
A portable oil filled room heater is a steel vessel typically with 5 to 8 fins containing approximately 3 to 4 liters of mineral oil. The mineral oil acts as the heat transfer fluid that is heated by an immersed electric heating element. The outward appearance of an oil filled heater is that of an old steam radiator.

An oil filled heater (OFH) exposed to full room involvement conditions will commonly display fire effects to include: rupture of the vessel’s spot welds, localized wavy deformations to the fins in the unwetted regions of the vessel, and differential deformation of the vessel’s fins. This study addresses the post-fire characteristics of oil filled heaters exposed to full room involvement conditions in two burn cells. A primary focus of the study is to determine if the pre-fire orientation of the oil filled heater can be determined by analysis of the post-fire appearance. A description of the dynamics that occur between the wetted and unwetted surfaces when the vessel is exposed to full room involvement conditions is discussed.

Analysis of an OFHs’ post-fire characteristics, to include vessel dimensions and wavy deformations, compared to the burn cell experiment results, allows an investigator to accurately interpret the normal reaction of an OFH to full room involvement as well as to determine its pre-fire orientation (upright or otherwise).

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Distinguishing Between Arcing and Melting Damage

DISTINGUISHING BETWEEN ARCING AND MELTING DAMAGE IN ELECTRICAL RECEPTACLES

Matthew Benfer and Daniel Gottuk
Hughes Associates Inc., USA

Presented at International Symposium on Fire Investigation, 2014

ABSTRACT

The majority of fire-investigation related literature on electrical arcing focuses on copper wiring, both stranded and solid, with some attention paid to steel (i.e., conduit), and relatively little mention of brass. This is despite the relatively equal presence of copper, steel, and brass in receptacles and similar electrical devices. Changes to NFPA 921 in the 2014 edition of the guide expand upon the characteristic traits which can be used to assess whether arcing or melting is present in a conductor. However, most of the characteristic traits of arcing and melting are qualitative and not well defined in NFPA 921, which leads to more subjective evaluations. In addition, a myopic examination of evidence with respect to the presence of one or two characteristic traits can lead to a false indication of arcing. In cases such as this, other evidence of melting (i.e., in close proximity to the area in question) could preclude confirmation of arcing.

The purpose of this work was to determine which characteristic traits are effective in assessing potential arcing damage on receptacle components and wiring. A total of 86 receptacles were evaluated in this study. Thirty-nine receptacles failed as a result of an overheating connection resulting in arcing damage; this included 95 individual conductors. Forty-seven receptacles with fire-induced arcing were also evaluated; this included 87 individual conductors. All of the evaluated receptacles with fire-induced arcing were energized or energized with a load during testing. In contrast, thirty-seven non-energized receptacles with fire induced melting were evaluated with 57 individual conductors.

The characteristic arcing traits which were evaluated include: corresponding damage on the opposing conductor; localized point of contact with a sharp line of demarcation between undamaged and damaged areas; round, smooth shape; resolidification waves; tooling marks visible outside the area of damage; internal porosity; spatter deposits; and small beads and divots over a limited area. The characteristic traits of melting which were evaluated include: visible effects of gravity; gradual necking of the conductor; and pitting, thinning, and presence of holes in the conductor. These traits were taken from the literature (e.g., NFPA 921) and from observations made during the forensic examinations of receptacles and wiring conducted as part of this work. For each characteristic, there were three possible outcomes: Yes, No, and Possible. Yes indicated that the characteristic was judged to be present on the particular conductor; no indicated that the characteristic was judged not to be present on the conductor. Possible indicated that confirmation could not be made either for or against the presence of the characteristic. All of the evaluations were conducted by the same person.

Corresponding damage on the opposing conductor, localized damage with a sharp line of demarcation, and tooling marks outside of the area of damage were observed on significant portions of arc damaged conductors and small numbers of conductors with melting damage; these characteristics were found to be strong indicators of arcing.

Using multiple characteristic traits and contextual information for determination of arcing vs. fire-melting provides greater confidence in the evaluation of damage. In addition, visual examinations were found to be reliable indicators of both arcing and fire-melting for most conductors. However, there are some cases which would benefit from more advanced examination techniques including SEM/EDS examinations, X-ray, CT scanning (X-ray computed tomography), cross-sectioning and polishing, or other metallurgical methods.

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Anatomy of a Wrongful Arson Conviction

ANATOMY OF A WRONGFUL ARSON CONVICTION: SENTINEL EVENT ANALYSIS IN FIRE INVESTIGATION

Paul Bieber, CFEI, B.S., M.L.S. The Arson Research Project

Presented at International Symposium on Fire Investigation, 2014

ABSTRACT

Anatomy of a Wrongful Arson Conviction will discuss the first comprehensive review of U.S. arson exonerations and the first application of sentinel-event and root-cause analysis to the field of fire investigation. Its purpose is to expose and explain the common factors that contribute to wrongful arson convictions.

Sentinel-event analysis has been embraced by several industries as an objective method of identifying and explaining the root causes of errors that have led to harmful outcomes. By reviewing dozens of arson cases, the Arson Research Project has documented the common errors at the heart of many fire investigations where accidental, natural or undetermined fires have been misidentified as arson.

This paper will also highlight the presence and impact of various forms of cognitive bias in each case study and emphasize the importance of objectivity and independence in the reliable application of the scientific method.

The 27 cases being reviewed include 19 exonerations, 7 cases where charges were dropped or a jury returned a not- guilty verdict, and one case that resulted in an execution. Together they represent over 200 years of combined incarceration and several life sentences. Even in the cases where the defendant was acquitted or the charges were dropped, the financial cost and emotional toll to the wrongfully accused were enormous. It is only through a clear examination and better understanding of these common errors that we may hope to avoid similar errors. This case- study review will attempt to shed some light on the problem in an ongoing effort to improve the practice of fire investigation and avoid future wrongful arson convictions.

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Plasma Ashing as a Fire Investigative Tool

Mark Goodson PE
Lee Green PE
Michael Shuttlesworth PE
Goodson Engineering
Denton, Texas USA

Presented at International Symposium on Fire Investigation, 2014

ABSTRACT
One of the difficulties that has faced engineers who examine electrical or mechanical items and / or devices after a fire is that of cleaning the item. The key adage in cleaning is essentially a medical command – primum non nocere, or “do no harm.” The cleaning technique will preferably cause no damage to the artefact being examined. Successful cleaning allows for both microscopic, visual, and SEM / EDX analysis.

In a fire, it is not uncommon for fire artefacts (wires, as an example) to require cleaning. Historical cleaning techniques have relied upon ultrasonic cleaning as a means for debris removal. Ultrasonic cleaning makes use of mechanical (sonic) energy to cause debris to dislodge from artefacts. How successful this technique is depends (in part) upon the energy imparted, the solvent used, and the interface between the wire and the debris. In the case of partially pyrolyzed PVC insulation, there are conditions that occur (depending upon the state or extent of pyrolysis) where no amount of mechanical agitation will remove the fire debris.

Oxides can be removed from wires by the use of surfactants or cleaners, some of which can have an etching effect on the metal. Treatments such as Alconox  or Simple Green  sometimes work sufficiently, while a more aggressive oxide remover (Branson OR)  relies on citric acid to help clean the wires. With more aggressive reagents, the user runs the risk of etching the metal and ruining the surface finish.

The writers describe a technique for removing fire debris from metal objects (wire, CSST) for use in removing fire debris. The technique is referred to as plasma ashing . In plasma ashing, a vacuum is created around the artefact, and a carrier gas is introduced (such as O2). An RF field (13.56 MHz) is applied, and the oxygen takes on a monatomic state. Essentially, a plasma i s created, and the monatomic O is free to react with organics associated with the fire debris. This process is also referred to as a glow discharge . The end result is that organics are removed from the artefact, and the ashing takes place at low temperatures – sufficiently low such that grain structure of the metal is not changed. This technique is essentially what is used in one of the manufacturing steps for making integrated circuits (ICs). As such, it imparts sufficiently low energy such that crystalline semiconductor structures are not damaged.

We compare and contrast plasma ashing with other modalities of cleaning. More particularly, we note (through visual microscopy) the efficacy of ashing and ultrasonic cleaning, as well as material removal rates. We show that despite its relative expensive capital costs, ashing represents a cleaning technique that does what other modalities fail to do – consistent removal of organic debris with no damage to the underlying substrate.

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The Application and Use of Digital Multimedia Evidence in Fire Investigations

 

James H. Shanley, Jr., PE, CFEI, CFI, MIFireE
Travelers Engineering Laboratory
and
James T. Noll
Travelers Engineering Laboratory

Presented at International Symposium on Fire Investigation, 2014

ABSTRACT

Digital multimedia is created in many forms and with increasing frequency with digital security systems, monitoring cameras, smart phones and other devices. Digital equipment and media obtained from these investigations should be handled in a specific way to preserve its integrity as potential evidence. In addition, Digital Multimedia may contain embedded data that can be clarified or analyzed to increase its value in a fire investigation.

The paper will review best practices with respect to handling digital equipment and multimedia in the context of a fire investigation. It will describe recovery and retrieval techniques and will aid the fire investigator in properly utilizing this growing resource of evidence.

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On-Scene Characterization of Flammable Liquid Vapors

ON-SCENE CHARACTERIZATION OF FLAMMABLE LIQUID VAPORS USING GC/MS AND SPME SAMPLING

J.D. DeHaan, Ph.D Fire-Ex Forensics Inc. USA
David A. Matthew, M.A. International Association of Fire Chiefs, USA
and
Gareth S. Dobson. Ph.D. Smiths Detection Inc. USA

Presented at International Symposium on Fire Investigation, 2014

ABSTRACT
There has not been a significant advancement in on-scene forensic fire debris analysis in over a decade. The ability to identify an accelerant at the fire scene would provide the fire investigator useful data, increasing efficiency and effectiveness. This research project was intended to establish if the identification of ignitable liquids can be achieved at the fire scene. Three testing sites in Utah, Texas and California provided data that the hand portable Gas Chromatography Mass Spectrometry (GC/MS) with Solid Phase Microextraction (SPME) fiber sampling technique is able to confirm the identity of ignitable liquid vapors at the fire scene consistent with fire debris analysis techniques. Post flashover testing was conducted at three sites in California and one in Utah providing replicable data confirming ignitable liquid vapor identification at low part per billion (ppb) and part per million (ppm) concentrations in real-world fires. The evidentiary samples taken at the testing sites in California were sent to a certified lab to confirm the results from the field data. The GUARDION ® GC/MS produced by Smiths Detection was used for field testing. A limiting factor in the field application of GC/MS was determined when the data produced had to be analyzed by a GC/MS specialist to confirm the identification of the ignitable liquid, similar to current laboratory techniques. It is recommended that a fire debris analysis method be developed to increase the field application of GC/MS.

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A Study of Calcination of Gypsum Wallboard

Christopher L. Mealy
Daniel T. Gottuk
Hughes Associates, Inc.

Presented at International Symposium on Fire Investigation, 2012

ABSTRACT

The prevalence of gypsum wallboard in fire scenes makes it a potentially valuable source of information to fire investigators when assessing a fire scene. The exposure of gypsum wallboard to heat from a fire can result in calcination, which in turn can theoretically be correlated to the total heat exposure to that area. Therefore, if properly characterized, a calcination depth profile of a given enclosure could provide fire investigators with a detailed history of the total heat exposure to the walls and ceiling of the space. This history, when combined with other findings, could provide valuable insight as to where the area of origin was located or how the fire developed. The approach taken in this work incorporated small- and full-scale testing to accomplish several goals: 1) develop an objective method for measuring the calcination depth of gypsum wallboard, 2) assess the utility of the calcination depth surveys in full-scale fires, and 3) characterize the impact of suppression water on calcination depth measurements. In this work a probing pressure of 0.86 kg/mm2  (1175 psi) was identified as providing accurate calcination depth measurements. The benefit of calcination depth surveys in full-scale enclosure fire scenarios was realized primarily for cases where visual patterns were not obvious. The application of water to calcined GWB was found to alter the measured depth of calcination by an average 18 percent, when collected 24 hours after heating/water application and less than five percent after 30 days. This data suggests that if measurements are to be collected in areas that have been wetted by suppression activities for any extended period of time, it would be advisable to delay measurements until the water has been removed.

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Scientific Method-Use, Application, and Gap Analysis for Origin Determination

 

Gregory E. Gorbett, MScFPE, CFEI, IAAI-CFI, CFII, CFPS
Eastern Kentucky University, USA
and
Wayne Chapdelaine, CFEI, IAAI-CFI, CFII
Metro-Rural Fire Forensics

Presented at International Symposium on Fire Investigation, 2014

ABSTRACT
The fire investigation industry is considered to be lagging behind the rest of the forensic science fields in its assessment of the performance of methodological approaches and conclusions drawn by practitioners within the field. Despite the best efforts of certifying bodies and industry members, there are still many unknowns within the profession. This paper will present practical uses of the scientific method as it relates to Origin Determination. Several recommended practices have been identified and formatted to reflect the scientific method as utilized in NFPA 921. In addition, where practical, a gap analysis has been conducted on these processes with recommendations provided.

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Fires Originating in Branch-Circuit NM Cables Due to Installation Damage

Vytenis (Vyto) Babrauskas, Ph.D.
Fire Science and Technology Inc., Issaquah WA

Presented at International Symposium on Fire Investigation, 2014

ABSTRACT
A significant fraction of US structure fires originate in electrical wiring, and there is also reason to believe that these numbers may be systematically undercounted. The role of voltage surges and damaged insulation in creating the potential for fire is discussed. That damaged electrical insulation may lead to fire has been known for a century, yet details of the mechanisms by which this occurs have not been extensively studied. UL recently published a study on damage due to poor workmanship in stapling of cables, specifically cases where the insulation is damaged but the conductors are not split. This study establishes that damage which may not appear visually striking may result in dielectric failure; such failures can be a direct cause of fire. Case histories are presented illustrating how mechanical damage associated with stapling of NM cables can result in serious fires. Two preventive measures are described: (a) installation by use of staplers and not hammers, and (b) testing the dielectric withstand voltage of branch circuits after installation and prior to energizing. Both of these measures, if implemented, should reduce the prevalence of electrical fires. However, given the immense amount of fixed wiring installed in buildings, fires due to damaged insulation do not imply that current wiring methods are a low-reliability technology. Only when serious installation defects are present does fire become a foreseeable event.

Keywords : dielectric strength of cables; electrical fires; forensic failure analysis; electrical installation defects; NM cables; voltage surges.

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Industrial Incident Investigation Techniques

Thomas V. Rodante, P.E., CFEI, CFII
Baker Engineering and Risk Consultants Inc., USA

Presented at International Symposium on Fire Investigation, 2012

ABSTRACT
NFPA 921 provides an excellent framework for individuals charged with the responsibility of investigating fire and explosion incidents. NFPA 921 establishes systematic investigative and analytical scientific techniques around the core principle of scientific methodology. Guidance is provided in NFPA 921 to show and explain the process of evidence collection, analysis, hypotheses formulation, forensic hypotheses testing, hypothesis correction and re-testing, and final cause determination. This presentation provides case study examples, not offered within NFPA 921, of forensic scientific methodology as applied to industrial petrochemical processing incidents.

Specific potential industrial evidence types are discussed and examples provided. The use of a timeline spreadsheet beyond that explained in NFPA 921 is shown with examples of how to correlate process data to witness statements. A case study scenario supposition and hypothesis spreadsheet is provided to show an example method for organizing observations, list related hypotheses, determine forensic test criteria, and document results. The provided example includes scientific forensic use of flame and vapor dispersion modeling, and metallurgical analysis. Finally, an example fault tree is shown as an alternative analytical method for cases in which the existence of physical evidence may be limited.

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