A variety of physical and chemical testing methods have been proposed for differentiating between an arc bead that caused a fire versus one that was caused by the fire itself. This is very useful information in determining the origin of fire due to electrical arcing and the spread of the fire. During the fire investigation process, arc beads are frequently encountered because electricity is available in most buildings undergoing a fire. Large enough fires will burn wiring to the extent that short circuits occur and numerous arc beads will be created. These type beads are termed the “victim” beads because they occurred after the fire started and were not the direct cause of the fire. Conversely, the beads that occur in wiring that produces the initial arc to set the fire are termed “cause” beads.

Methods for determining whether the arc bead is a cause or victim bead include examining the physical property of the bead. Some of these include examining the glossiness of the bead, color, shape, surface features, and size. These physical methods can be relied on for arc bead differentiation, however instrumental analysis techniques can also be used. These include, but are not limited to, microscopy, Raman spectroscopy, X-ray microanalysis, Auger electron spectroscopy (AES), and secondary ion mass spectrometry (SIMS).

Though it has not been scientifically proven, researchers have postulated that an arc bead formed without a pre-existing fire would be formed in an oxidizing atmosphere, while one that occurred after a fire was ongoing would be formed in a reducing atmosphere. Thus, profiles of the oxygen concentration, as a function of depth below the surface of the bead, would enable identification to be made. Moreover, the atmosphere surrounding a victim bead will contain material that originated from decomposing solids nearby, while that around a cause bead will not. Adequate amounts of this material, such as carbon, will be found in the victim bead. Techniques to measure the oxygen and carbon concentration have been used, including auger electron spectroscopy (AES).

There are limitations to this theory, however, because “cause” arc beads can occur in environments where the insulation has substantially degraded, and also a short-circuit due to molten wire can occur during a fire in a protected environment where there are no combustion products and minimum pyrolysis.

RWFE, LLC is not responsible for damages of any kind arising out of use, reference to, or reliance on any information contained within these articles. While the information contained with the articles is periodically updated, no guarantee is given that the information provided is correct, complete, and up-to-date. Although these articles may include links providing direct access to other Internet resources, RWFE, LLC is not responsible for the accuracy or content of information contained in these resources.

The CPSC is participating in a study in order to develop safety-related performance requirements for treestand and treestand harnesses. The voluntary standards establish the procedures and requirements for testing treestand load capacity, static stability, and repetitive loading capacity. They also establish the test methods for dynamically evaluating fall arrest systems (harnesses). The CPSC is continuing to study ways to identify and eliminate potential strangulation risks that may be associated with harnesses, and improve the safety of harnesses and self-rescue measures.

CPSC Staff Reports, Memoranda and Contracts:

• Briefing Package on Petition CP-02-3 regarding Hunting Tree Stands, Part 1
• Briefing Package on Petition CP-02-3 regarding Hunting Tree Stands, Part 2

Safety Alerts:

• Hunting Treestands and Harnesses, CPSC Publication #5200

RWFE, LLC is not responsible for damages of any kind arising out of use, reference to, or reliance on any information contained within these articles. While the information contained with the articles is periodically updated, no guarantee is given that the information provided is correct, complete, and up-to-date. Although these articles may include links providing direct access to other Internet resources, RWFE, LLC is not responsible for the accuracy or content of information contained in these resources.

Ford was also investigating 2003 model-year F-Series Super Duty pickup trucks equipped with the 6.0 liter diesel engines due to various engine performance issues, and also recalled 78,675 Super Duty pickups and chassis cab vehicles from the 2005 model year because their fuel line may separate from the main fuel bundle. Fuel line separation can cause engine stalling or leakage, possibly resulting in a fire. The agency identified the trucks affected by the recall as F-250, F-350, F-450 and F-550 Super Duty pickups with 5.4 or 6.8 liter gasoline engines.

Several class action lawsuits have been filed against the Ford Motor Company, Inc. by owners and lessees of Ford F250 / F350 Super Duty trucks and Excursion vehicles have alleged that the Ford 6L Power Stroke Diesel Engines suffer from serious manufacturing and design defects. RWFE, LLC specializes in investigating vehicle fires or accidents due to these types of recalls and have investigated recalled vehicle components such as gas tanks, fuel lines, engines, cooling systems, and electrical and wiring.

RWFE, LLC is not responsible for damages of any kind arising out of use, reference to, or reliance on any information contained within these articles. While the information contained with the articles is periodically updated, no guarantee is given that the information provided is correct, complete, and up-to-date. Although these articles may include links providing direct access to other Internet resources, RWFE, LLC is not responsible for the accuracy or content of information contained in these resources.

Metal halide bulbs produce light by making an electric arc in a mixture of gases. The compact arc tube contains a high pressure mixture of argon, mercury, and a variety of metal halides. The argon gas within the bulb is easily ionized, and facilitates striking the arc across two electrodes within the lamp once voltage is applied. The heat generated by the arc vaporizes the mercury and metal halides, which in turn produce light as the temperature and pressure increases.

All metal halide bulbs will fail over time because the tube that holds the arc deteriorates in strength because of various factors, such as chemical attack, thermal stresses, mechanical vibration, and sometimes manufacturing or design defects.

Because metal halides contain gases at a very high pressure, failure of the arc tube will cause a very violent event, launching hot fragments and sometimes breaking the outer bulb. The hot pieces of debris are likely to fall down onto people and property below the bulb, causing injury or damage such as a structure fire if flammable materials are present.

RWFE, LLC has recently done case work on metal halide failure and we are very knowledgable on fires that may have been caused by metal halide bulb failures. Structural fires are very common due to these halide bulbs and should be investigated by a Certified Fire Investigator (CFEI) as well as a Mechanical and Electrical Engineer, all of which we have on staff.

RWFE, LLC is not responsible for damages of any kind arising out of use, reference to, or reliance on any information contained within these articles. While the information contained with the articles is periodically updated, no guarantee is given that the information provided is correct, complete, and up-to-date. Although these articles may include links providing direct access to other Internet resources, RWFE, LLC is not responsible for the accuracy or content of information contained in these resources.

http://www.tmastands.com/recalls.php

http://www.cpsc.gov/cpscpub/prerel/prhtml10/10036.html

http://www.consumerwatch.com/hunting-tree-stands/recall.php

RWFE, LLC is not responsible for damages of any kind arising out of use, reference to, or reliance on any information contained within these articles. While the information contained with the articles is periodically updated, no guarantee is given that the information provided is correct, complete, and up-to-date. Although these articles may include links providing direct access to other Internet resources, RWFE, LLC is not responsible for the accuracy or content of information contained in these resources.

Heat transfer is defined as the transport of heat energy from one point to another caused by a temperature difference between those two points. Unless work is being done on the system by outside forces, heat is naturally transferred from a higher temperature mass to a lower temperature mass. The three heat transfer are conduction, convection, and radiation.

Conduction is a form of heat transfer that takes place within solids when one portion of an object is heated. Energy is transferred from the heated area to the unheated area at a rate dependent on the difference in temperature and the thermal conductivity of the material.

Convection is the transfer of heat energy by the movement of heated liquids or gases from the source of heat to a cooler part of the environment. In the early part of a fire, convection plays a major role in heating the surfaces exposed to gases heated by the fire.

Radiation is the transfer of heat energy from one hot surface or gas, the radiator, to a cooler material by electromagnetic waves without the need of an intervening medium. Radiation explains flashover.

RWFE, LLC is not responsible for damages of any kind arising out of use, reference to, or reliance on any information contained within these articles. While the information contained with the articles is periodically updated, no guarantee is given that the information provided is correct, complete, and up-to-date. Although these articles may include links providing direct access to other Internet resources, RWFE, LLC is not responsible for the accuracy or content of information contained in these resources.

A fuel is any substance that can undergo combustion. It is generally organic and can be a solid, liquid, or gas. However, fuels can only be consumed in the vapor state. Therefore, combustion of liquid fuels and most solid fuels takes place above the fuel surface in a region of vapors created by heating the fuel surface. Gaseous fuels, however, do not require vaporization or pyrolysis before combustion can occur and only proper mixture with an oxidizer and an ignition source are needed.

Heat can come from ambient conditions, from an ignition source, or from exposure to an existing fire. Heat produces fuel vapors, causes ignition, and promotes fire growth and flame spread by maintaining a continuous cycle of fuel production and ignition. The heat energy must be above the minimum level necessary to release fuel vapors and cause ignition.

The oxidizing agent is generally oxygen found in the earth’s atmosphere, but can be a chemical oxidizer as well, such as ammonium nitrate fertilizer. The fuel to air ratio has an optimum ratio at which combustion will be most efficient.

The oxidation reaction, or burning, must produce enough heat to maintain burning. Combustion is a complex set of chemical reactions that results in the rapid oxidation of a fuel, producing heat, light, and a variety of chemical by-products. If this complex chain reaction is uninhibited, a fire will sustain itself and most likely spread.

RWFE, LLC is not responsible for damages of any kind arising out of use, reference to, or reliance on any information contained within these articles. While the information contained with the articles is periodically updated, no guarantee is given that the information provided is correct, complete, and up-to-date. Although these articles may include links providing direct access to other Internet resources, RWFE, LLC is not responsible for the accuracy or content of information contained in these resources.

A design flaw was clearly the major factor in the disaster, however routine inspections of bridges never required an inspection of gusset plates. Bridge capacity, or load rating, was never considered to be effected by gusset plates until this disaster. It was assumed that gusset plates were properly sized to be stronger than the members they connect. In order to assist with the process of analyzing gusset plate strength, guidance was sought in order to “load rate” gusset plates.

Because there was little information on the failure modes of gusset plates, The Federal Highway Administration (FHWA) along with the National Institution of Standards and Technology (NIST), began building full-scale models of bridge gusset plate joints and pulling them apart using a hydraulic test machine. There was a need to measure how the gusset plates failed, which brought about a technology that has been used forever – Photogrammetry. Through the use of photographic measurement of paint specks, digital images allows engineers to watch the failure of key bridge components in great detail.

Click here to view the embedded video.

There is a lot to gain from correlating the digital image method to the FHWA actual measurement methods. First, it tells the FHWA the normal ranges of stress in which the plates can handle and will spring back into their original shape. Second, the method really shows what happens past the normal stress point – when the plate starts to permanently deform and eventually fails. With this new technology, the FHWA has learned a lot about how to predict what loads will cause gusset plates to fail.

The FHWA is working to translate the findings into a language that can be adopted into the Bridge Design Specification and Manual for Bridge Evaluation, two documents that are used in the US for designing and load rating bridges.

See Article: http://www.asminternational.org/portal/site/www/NewsItem/?vgnextoid=49ab76a8253d4310VgnVCM100000621e010aRCRD

RWFE, LLC is not responsible for damages of any kind arising out of use, reference to, or reliance on any information contained within these articles. While the information contained with the articles is periodically updated, no guarantee is given that the information provided is correct, complete, and up-to-date. Although these articles may include links providing direct access to other Internet resources, RWFE, LLC is not responsible for the accuracy or content of information contained in these resources.

The origin and cause of the fire should be determined by using the scientific method. Thus, the investigator should recognize the need, define the problem, collect data, analyze the data, develop a hypothesis, test the hypothesis, and most importantly, avoid presumption, expectation bias, and confirmation bias. All investigations should be approached without any presumptions, and investigators should never reach a premature conclusion without having examined or considered all relevant data. Also, the investigator should never try to prove the hypothesis is right, and testing should be done to disprove the hypothesis.

After a fire or explosion incident occurs, the investigator should be notified of what his or her role will be in the investigation. The investigator should prepare for the investigation by estimating which tools, equipment, and personnel will be needed. The actual investigation may include different steps and procedures, which will be determined by the purpose of the assignment. The goal is to arrive at accurate determinations related to origin, cause, fire spread, and responsibility for the incident. Evidence should be documented properly and preserved for testing and courtroom presentation. Once data is collected, it should be analyzed using the scientific method. Conclusions are drawn as a result of testing the hypothesis.

The four causes of fire highlighted by the National Fire Protection Association’s National Fire Code NFPA 921 are natural, accidental, intentional, and undetermined. Often the local fire department has an investigation team who determined the origin and cause of the fire. However, consulting and litigation firms such as RWFE can be hired to investigate the fire as well by insurance companies or the private sector. The ATF comes in for drastic events or where criminal activity may be present.

Fire investigation is inherently a multidisciplinary activity. Therefore, special expertise from different fields would facilitate the investigation to reach a reasonable conclusion with sound evidence. Experts include many types of engineers including electrical engineers, chemical engineers, and mechanical engineers. An electrical engineer understands how electricity can be converted to heat and light and energy. A chemical engineer understands fires involving chemicals in the ignition, cause, or spread of the fire. A mechanical engineer can help investigate machine parts, such as bearing or other sources of friction. Moreover, a forensic scientist understands fire chemistry as well as the elements of arson.

The levels of certainty in a fire investigation are important because they describe how strongly someone holds an opinion or conclusion. These levels are determined by assessing the investigators confidence in the data, analyses of the data, and testing of the hypotheses. The level may determine the practical application of the opinion such as in legal proceedings. The two levels commonly used are “probable” and “possible”. Probable is described when a statement is more likely true than not (>50%), whereas possible is described when a hypothesis is demonstrated to be feasible but not declared probable. If two or more hypotheses are equally likely, then the level of certainty must be “possible”. If the level of certainty is “suspected”, the opinion does not qualify as an expert opinion.

Lastly, there are review procedures for all fire investigation reports. An administrative review is a review that is typically carried out within an organization to ensure that the investigators work product meets the quality assurance requirements. A technical review is a review by someone qualified and familiar with all aspects of proper fire investigation and should, at a minimum, have access to all of the documentation available to the investigator. A peer review is a review by someone who has no interest in the outcome of the review, thus the reviewer should not be a coworker or supervisor. All three types of reviews are important to the report and should be carried out if possible.

RWFE, LLC is not responsible for damages of any kind arising out of use, reference to, or reliance on any information contained within these articles. While the information contained with the articles is periodically updated, no guarantee is given that the information provided is correct, complete, and up-to-date. Although these articles may include links providing direct access to other Internet resources, RWFE, LLC is not responsible for the accuracy or content of information contained in these resources.

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RWFE, LLC is not responsible for damages of any kind arising out of use, reference to, or reliance on any information contained within these articles. While the information contained with the articles is periodically updated, no guarantee is given that the information provided is correct, complete, and up-to-date. Although these articles may include links providing direct access to other Internet resources, RWFE, LLC is not responsible for the accuracy or content of information contained in these resources.