NAFI Blog

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).

Download the complete paper here

There has been a lot of debate in fire investigation industry recently regarding Arc Mapping.  NAFI’s mission is to increase the knowledge and improve the skills of persons engaged in the investigation and analysis of fires, explosions and arsons, or the litigation that ensues from such investigations. The opinions expressed in this paper do not necessarily reflect the opinion and beliefs of NAFI. Over the next three weeks, we will be sharing different views on Arc Mapping with our members and the industry – it is up to you to draw your own conclusions.

Week 1 – Arc Mapping: New Science or New Myth?
Week 2 – Arc Mapping as a Tool for Fire Investigations

ATF Fire Research Laboratory Technical Bulletin
Arc Mapping as a Tool for Fire Investigations

ABSTRACT
The purpose of this Technical Bulletin is to address statements that are contained in Arc Mapping: New Science or New Myth?, which was presented at the Fire and Materials Conference in February 2017. The paper’s interpretations and analysis of the published literature, the limitations it places on the process of arc mapping, and the conclusion that arc mapping is applicable to less than 1% of fire scene investigations are misleading. This bulletin addresses some of these issues.

Download the entire technical bulletin here.

There has been a lot of debate in fire investigation industry recently regarding Arc Mapping.  NAFI’s mission is to increase the knowledge and improve the skills of persons engaged in the investigation and analysis of fires, explosions and arsons, or the litigation that ensues from such investigations. The opinions expressed in this paper do not necessarily reflect the opinion and beliefs of NAFI. Over the next three weeks, we will be sharing different views on Arc Mapping with our members and the industry – it is up to you to draw your own conclusions.

Week 1 – Arc Mapping: New Science or New Myth?
Week 2 – Arc Mapping as a Tool for Fire Investigations
Week 3 – Arc Mapping: A Review of Findings

Vytenis Babrauskas
Fire Science and Technology Inc., San Diego, CA
Dept. of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA

ABSTRACT
Arc mapping was first introduced in the 2001 edition of NFPA 921 and was subsequently expanded so that in the recent editions it constitutes one of the four main methods for determining the origin of a fire. Careful consideration of engineering principles and large-scale experimental studies on the subject indicates that the relevance and prominence of arc mapping as a leading indicator of fire origin is greatly overstated. The technique is valid and applicable only in some very limited scenarios. Yet it has seen very extensive use in recent years by investigators preparing fire reports. In many cases, such attempted use of arc mapping is based on incorrect and invalid hypotheses, which are often implicitly assumed to be true instead of being explicitly stated. The following are myths: (i) An abundance of arc beads at a given locale means that fire originated in that area, while a paucity of arc beads indicates that it did not. (ii) When multiple arcs are present on a circuit, the direction of arcing will necessarily proceed upstream towards the power source. (iii) If an appliance is the victim of a fire, internal arcing will be primarily near the exterior of the unit, while arcing deep inside indicates a fire origin at that place. NFPA is urged to revise NFPA 921 to eliminate arc mapping as one of the four main methods for establishing fire origin, and to subsume it under the more general category of “fire patterns.” In addition, it is important that NFPA 921 reduce the implied general utility of the method and provide more explicit information on its interpretation and its limitations and on the circumstances under which it may be a valid method for assisting in the determination of the fire origin.

Download the complete paper here

The St. John’s School fire was a deadly fire that occurred on the morning of October 28, 1915, at the St. John’s School on Chestnut Street in the downtown area of Peabody, Massachusetts. Twenty-one girls between the ages of 7 and 17 were burned or crushed to death while attempting to escape the fire.

More than 600 children were in the building when the fire began in the basement of the school building. There were no fire escapes on the outside of the building, but instead those inside were forced to use wide stairways at either end of the interior which led down to the front exit. Mother Superior Aldegon, who led the Sisters who taught in the Catholic school, sounded a fire alarm and began the routine fire drill procedure.

This procedure should have led to the children and teachers leaving the building through the stairways to and out of a rear exit. However, as smoke thickened and the fire came closer, they ran for the front door instead, and became jammed in the vestibule. The fire broke through to the vestibule from directly under the front entrance and the vestibule, now crowded with pupils, was enveloped in flames. The fire rapidly swept through the three-story brick and wooden building, fully engulfing it in less than five minutes.

With their exit blocked, many of the children escaped through first-floor windows or jumped from those on the second and third floors. Not all were able to escape, however; the bodies of the 21 victims were found after the fire subsided, huddled together and burned beyond recognition, on the inside of the school entrance. The Sisters of Notre Dame who taught at St. John’s aided the children trying to escape, some by dropping the students into coats and blankets being used as life nets. These actions were credited in saving many lives. Two of the nuns were injured, one suffering serious burns; however, none of the adults were killed.

As a result of this fire, Peabody became the first city to pass a law that said all doors (in public buildings and school) must push out.

Source: Wikipedia

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.

Download the complete paper here.

More than 1,000 people taking a pleasure trip on New York City’s East River are drowned or burned to death when a fire sweeps through the boat. The General Slocum disaster was the New York area’s worst disaster in terms of loss of life until the September 11, 2001 attacks. It is the worst maritime disaster in the city’s history, and the second worst maritime disaster on United States waterways.

The riverboat-style steamer General Slocum was built in 1890 and used mostly as a vehicle for taking large groups on day outings. On June 15, the St. Mark’s German Lutheran Church assembled a group of 1,360 people, mostly children and teachers, for their annual Sunday School picnic. The picnic was to take place at Locust Point in the Bronx after a cruise up the East River on the General Slocum.

At about 9 a.m., the dangerously overcrowded boat left its dock in Manhattan with Captain William Van Schaik in charge. As the boat passed 83rd Street, accounts indicate that a child spotted a fire in a storeroom and reported it to Captain Van Schaik. Reportedly the captain responded, “Shut up and mind your own business.” But as the smoke became more obvious, crew members were sent to investigate. By this time, the storeroom, filled with a combination of oil and excelsior (wood shavings used for packing), was blazing out of control. The onboard fire hose, which had never been used, tested or inspected, did not work.

Captain Van Schaik made a fateful decision at this time. Instead of directing the boat to the nearest dock where firefighters could engage the fire, he pointed the boat toward a small island in the East River. He later told investigators that he did not want to risk spreading the fire to the dock and the rest of the city, but the strategy proved deadly for the passengers. Instead of grounding the boat on the sand, the boat crashed onto the rocks of the island’s shore.

At this point, other factors also combined to exacerbate the situation. The lifeboats were so firmly tied to the steamer that they could not be released. The life preservers had not been filled with cork, but a non-buoyant material that made them weighty. The children who used them sank to the bottom of the river. Other children were trampled to death in the panic. More people were killed when the raging fire collapsed some of the decks, plunging them into the fire.

In all, 630 bodies were recovered and another 401 were missing and presumed dead. A cannon was brought to the scene and fired over the river the next day to loosen bodies from the river mud. The boat’s crew, and officers in the Knickerbocker Company, owner and operator of the General Slocum, were charged with criminal negligence. However, only Captain Van Schaik received a prison sentence. He was supposed to serve 10 years, but was pardoned due to old age in 1908. President Theodore Roosevelt fired the chief inspector of the U. S. Steamboat Inspection Service in the aftermath of the accident; wholesale changes in the industry followed. A mass grave was set up in Queens for the victims and a yearly memorial was held to honor their memory.

Source: History.com
Image: The Library of Congress – shows the mass of burned timbers and ruined metal, showing broken paddle wheels shaft.

A fire in an overcrowded Honduras prison kills 103 people on May 17, 1994. An overheated refrigerator motor sparked the horrible blaze that raced through the outdated jail. Only a year earlier, a gang fight at the same prison had left nearly 70 people dead.

The prison, in San Pedro Sula, 100 miles north of the Honduran capital of Tegucigalpa, was largely devoted to housing gang members arrested in a recent crackdown. This new emphasis on jailing gang members resulted in a prison population of nearly 2,000, although the structure was built to accommodate only 800. The fire and explosion took place in a cell block that housed 186 prisoners belonging to the Mara Salvatrucha gang, also known as MS-13. The fire started in one of two small refrigerators located in the cell block at about 1:30 a.m. Prisoner Jose Lopez reported, “Everything happened fast. We woke up with our clothes and our beds in flames.” Guards reported that they had to fire their guns in the air in order to keep the prisoners from attacking the firefighters and escaping. Inmates claimed that the guards were preventing the prisoners from fleeing the fire.

As news of the fire became public, relatives of the prisoners began gathering outside the prison. Officials then placed the bodies of the dead in rows on the ground for identification, which was often made through their elaborate gang-related tattoos, before refrigerated trucks transported them to a morgue.

The Honduran government continued its anti-gang activity in the wake of the tragedy, but also took steps to prevent prison overcrowding.

Source: History.com

On this day in 1937, the German airship Hindenburg, the largest dirigible ever built, explodes as it arrives in Lakehurst, New Jersey. Thirty-six people died in the fiery accident that has since become iconic, in part because of the live radio broadcast of the disaster.

The dirigible was built to be the fastest, largest and most luxurious flying vessel of its time. It was more than 800 feet long, had a range of 8,000 miles, could carry 97 passengers and had a state-of-the-art Mercedes-Benz engine. It was filled with 7 million cubic feet of hydrogen, even though helium was known to be far safer, because it made the flying ship more maneuverable.

The Hindenburg had made 10 successful ocean crossings the year before and was held up by Germany’s Nazi government as a symbol of national pride. Flying at a speed of 85 miles per hour, the Hindenburg was scheduled to arrive in New Jersey at 5 a.m. on May 6. However, weather conditions pushed the arrival back to the late afternoon and then rain further delayed the docking at Lakehurst. When the dirigible was finally cleared to dock, Captain Max Pruss brought the ship in too fast and had to order a reverse engine thrust. At 7:20 p.m., a gas leak was noticed. Within minutes, the tail blew up, sending flames hundreds of feet in the air and as far down as the ground below.

A chain reaction caused the entire vessel to burn instantly. The nearly 1,000 spectators awaiting the Hindenburg‘s arrival felt the heat from a mile away. Some on the blimp attempted to jump for the landing cables at the docking station but most died when they missed. Others waited to jump until the blimp was closer to the ground as it fell. Those who were not critically injured from burns often suffered broken bones from the jump. Fifty-six people managed to survive.

On WLS radio, announcer Herbert Morrison gave an unforgettably harrowing live account of the disaster, “Oh, oh, oh. It’s burst into flames. Get out of the way, please . . . this is terrible . . . it’s burning, bursting into flames, and is falling . . . Oh! This is one of the worst . . . it’s a terrific sight . . .oh, the humanity.”

Source: History.com