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

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.

Download the complete paper here

1984, Feb 25:  Explosion kills hundreds in Brazil

On February 25, 1984, a huge explosion destroys a shantytown in Brazil, killing at least 500 people, mostly young children. An investigation into the disaster later revealed that the true death count was impossible to know because so many bodies had in effect been cremated in the intense blaze.

The shantytown in Cubatao, 30 miles southeast of Sao Paulo, was known as the Vila Soco favela. Approximately 9,000 people had set up makeshift homes on land that was owned by Petrobas, the state-run oil monopoly. Gas pipelines operated by Petrobas ran next to the slum. When workers opened the wrong pipeline on February 24, highly combustible octane gas poured into the ditches of Vila Soco. Soon after midnight, an explosion was sparked, and a fireball ripped through the favela. Some homes were literally thrown hundreds of feet into the air; others were instantly incinerated. The temperature at the heart of the fireball was estimated at 1,800 degrees Fahrenheit.

A day later, only 86 bodies had been recovered. None of the remains were of children below the age of seven, though investigators later found that more than 300 children aged three to six had been enrolled in a local school prior to the explosion and that only 60 were known to be alive. Coroner Affonso Figueiredo reported, “Since whole families were killed, there was no one to report the children’s death or disappearance.” It is believed that more than 500 people in all were killed.


1967, Jan 27: Astronauts die in launch pad fire

A launch pad fire during Apollo program tests at Cape Canaveral, Florida, kills astronauts Virgil “Gus” Grissom, Edward H. White II, and Roger B. Chafee. An investigation indicated that a faulty electrical wire inside the Apollo 1 command module was the probable cause of the fire. The astronauts, the first Americans to die in a spacecraft, had been participating in a simulation of the Apollo 1 launch scheduled for the next month.

The Apollo program was initiated by the National Aeronautics and Space Administration (NASA) following President John F. Kennedy’s 1961 declaration of the goal of landing men on the moon and bringing them safely back to Earth by the end of the decade. The so-called “moon shot” was the largest scientific and technological undertaking in history. In December 1968, Apollo 8 was the first manned spacecraft to travel to the moon, and on July 20, 1969, astronauts Neil A. Armstrong and Edwin “Buzz” Aldrin Jr. walked on the lunar surface. In all, there were 17 Apollo missions and six lunar landings.


The Application and Use of Digital Multimedia Evidence in Fire Investigations


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

Presented at International Symposium on Fire Investigation, 2014


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.

Download the complete paper here

1969, Jan 14:  Explosion rocks USS Enterprise

An explosion aboard the aircraft carrier USS Enterprise kills 27 people in Pearl Harbor, Hawaii, on this day in 1969. A rocket accidentally detonated, destroying 15 planes and injuring more than 300 people.

The Enterprise was the first-ever nuclear-powered aircraft carrier when it was launched in 1960. It has eight nuclear reactors, six more than all subsequent nuclear carriers. The massive ship is over 1,100 feet long and carries 4,600 crew members.

At 8:19 a.m. on January 14, a MK-32 Zuni rocket that was loaded on an F-4 Phantom jet overheated due to the exhaust from another vehicle. The rocket blew up, setting off a chain reaction of explosions. Fires broke out across the deck of the ship, and when jet fuel flowed into the carrier’s interior, other fires were sparked. Many of the Enterprise’s fire-protection features failed to work properly, but the crew worked heroically and tirelessly to extinguish the fire.

In all, 27 sailors lost their lives and another 314 were seriously injured. Although 15 aircraft (out of the 32 stationed on the Enterprise at the time) were destroyed by the explosions and fire, the Enterprise itself was never threatened.

The USS Enterprise was repaired over several months at Pearl Harbor and returned to action later in the year.


Fire breaks out on Queen Elizabeth

On January 8 in 1972, the ship Seawise University (formerly the RMS Queen Elizabeth) sinks in Hong Kong Harbor despite a massive firefighting effort over two days.

The Queen Elizabeth, named after the wife of King George VI, was launched on September 27, 1938; at the time, it was the largest passenger steamship ever constructed. When World War II began, the Queen Elizabeth was sent to New York to protect it from German bombs. There, it was docked next to the Normandie and the Queen Mary, the other two largest passenger ships of the time.

Later, the Queen Elizabeth was called into service as a troop transport ship, carrying nearly 1 million soldiers during the war. Following the war, the ship returned to commercial service and became one of the dominant transatlantic carriers, hauling thousands of people back and forth between England and the United States. In 1968, the ship’s owner, the Cunard Steamship Company, sold the Queen Elizabeth to a company that sought to turn it into a tourist attraction and hotel in Philadelphia. However, the aging ship was deemed a fire hazard and two years later it was sold to Hong Kong businessman C.Y. Tung, who wanted to use the ship as a floating college. It was renamed Seawise University and sent to Hong Kong Harbor for refitting.

On January 8, fire broke out on the ship and virtually the entire Hong Kong firefighting force turned out to try to save it. Despite heroic efforts over two days, the old ship turned on its side and sank to the bottom of the harbor. Fortunately, no one was killed. Two years later, the wreck served as the backdrop for a key scene in The Man With the Golden Gun, a 1974 film starring Roger Moore as James Bond.


On-Scene Characterization of Flammable Liquid Vapors


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

Presented at International Symposium on Fire Investigation, 2014

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.

Download the complete paper here


Fire Investigator Qualifications Standard Approved for OSAC Registry

NAFI has endorsed National Fire Protection Association (NFPA) 921 Guide for Fire and Explosion Investigations since the first edition was released in 1992. NFPA 921 has been a key source of technical information concerning the investigation of Fires and Explosions.  NAFI has also utilized and supported NFPA 1033 Professional Qualifications for Fire Investigators as this document provides guidance concerning the knowledge and competencies that a Fire and Explosion Investigator must have to effectively complete and investigation. Having these two documents selected and approved to be included in the Organization of Scientific Area Committees (OSAC) for Forensic Science registry which serves as a trusted repository of high-quality, science-based standards and guidelines for forensic practice is testimony that these documents are truly authoritative. Both of these documents have been key elements in the development and continuation of the NAFI Certified Fire and Explosion Investigator (CFEI) and Certified Vehicle Fire and Explosion Investigator (CVFI) programs. – Ron Hopkins, President, NAFI

The Organization of Scientific Area Committees (OSAC) for Forensic Science has approved the National Fire Protection Association (NFPA) Standard for Professional Qualifications for Fire Investigator for inclusion on the OSAC Registry, which serves as a trusted repository of high-quality, science-based standards and guidelines for forensic practice. This is the first personnel qualification standard and the second NFPA document to be included on the OSAC Registry.

OSAC, which is administered by the National Institute of Standards and Technology (NIST), is working to strengthen forensic science by facilitating the development of discipline-specific, science-based standards and guidelines for a broad array of forensic disciplines. To be posted to the OSAC Registry, standards and guidelines must have been developed using a consensus-based process and must pass a review of technical merit by forensic practitioners, academic researchers, statisticians and measurement scientists. Continue Reading…


1906, Dec 6th:  Monongah coal mine disaster

In West Virginia’s Marion County, an explosion in a network of mines owned by the Fairmont Coal Company in Monongah kills 361 coal miners. It was the worst mining disaster in American history.

In 1883, the creation of the Norfolk and Western Railway opened a gateway to the untapped coalfields of southwestern West Virginia. New towns sprung up in the region virtually overnight as European immigrants and African Americans from the south poured into southern West Virginia in pursuit of a livelihood from the new industry.

By the late 19th century, West Virginia, now a national leader in the production of coal, fell far behind other major coal-producing states in regulating mining conditions. In addition to poor economic conditions, West Virginia had a higher mine death rate than any other state. Nationwide, a total of 3,242 Americans were killed in mine accidents in 1907. In ensuing decades, the United Mine Workers of America labor union and sympathetic legislators forced safety regulations that brought a steady decline in death rates in West Virginia and elsewhere.


A Study of Calcination of Gypsum Wallboard

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

Presented at International Symposium on Fire Investigation, 2012


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.

Download the complete paper here