Posts Tagged ‘Fire Investigation’

by: Jason A. Sutula

Hello and welcome to the Fire Science Blog! For those of you who are new visitors to this site, the genre of this blog is anything and everything related to fire and fire science. As a fire scientist, I consider it my mission to educate and inform on all topics related to fire, fire investigation, and fire protection. By education, I am a fire protection engineer with degrees from the University of Maryland and the University of Edinburgh in Scotland. By experience, I have been fortunate to research how fire behaves and the best method of putting it out (my favorite project was learning how fire operates in outer space!). By training, I am a Certified Fire and Explosion Investigator and have been conducting forensic analyses of fire and explosion incidents for over 16 years.

Today’s post is an opportunity like no other. The Fire Science Blog was selected for hosting Samarra Khaja (SK), author of her new book Sew Adorkable: 15 DIY Projects to Keep You Out of Trouble (C&T Publishing, $26.95) on her book blog tour.


Gifted and schooled in the fine arts, Samarra Khaja is a designer, photographer, art director, and illustrator. Her work can be found in The New York Times, The Guggenheim, Time magazine, and Cirque du Soleil to name a few.

SK came to the Fire Science Blog with many questions from herself and her main audience regarding the fire safety and flammability of various fabrics and materials used in fabric design, sewing, and the equipment used. It is my great honor to present SK as the host of this question and answer session.

Jason Sutula (JS), thanks so much for fielding my fire-related questions. As you know, aside from my book being filled with fun projects, it’s also full of fun facts. So on this blog tour I thought it only appropriate to continue to provide my audience with fun facts and you, JS, are my living, breathing anthropomorphized fun fact section for this event. Sound good? Great, let’s get to it!

 SK- Sewing, crafting and DIY projects are really hot right now. That said, should I fear that my book will spontaneously combust? What’s the real world risk of that?

JS- One of the first books I remember reading in high school was Fahrenheit 451 by Ray Bradbury. The premise was a dystopian society where books were outlawed and burned by “Firemen.” 451 degrees Fahrenheit was the temperature that Mr. Bradbury decided on for the ignition temperature of paper in his story. I learned over my schooling and career that the type of paper, whether it is tissue, newsprint, glossy, or engineering paper, determines the fundamental material properties of the paper that control the ignition temperature. Mr. Bradbury was not far off though, as “book” paper has an establish ignition range between 437 °F and 464 °F. The good news then is that a single one of your books sitting out on a coffee table has no chance of spontaneously bursting into flame.

SK- The materials for the projects have been left to the discretion of the maker. From a fire-safety stand point, what are the safest and least safe fabrics to use?

 JS- When scanning the internet, I came across a great article in the Fall 2011 edition of On Track! magazine, which you may have some familiarity with. The article is titled, “Safe Batting Choices for Baby and Invalid Quilts,” by Beth Kurzava. The article does a great job of demonstrating how easy or hard it is to spread flame over different batting materials. Cotton, wool, silk, cotton-poly blends, polyester, bamboo-cotton blends, cotton-corn blends, and fire retardant cotton fabrics were all tested following an ad hoc procedure based on the code of federal regulations (CFR) clothing fabric flammability test. The test was simple, expose an 8” square of each fabric on a 45 degree incline to a three second fire exposure at the corner of the sample, then sit back and observe the fire spread. Pictures were provided in the article and show that wool and fire resistant cotton are the best performers and polyester is the worst performer. These results are very consistent with the science of fabric flammability. Natural fibers will burn or smolder, but are naturally resistant to rapid fire spread over a surface. Polyester, on the other hand, is a petroleum-based, plastic synthetic fiber. Like all petroleum-based plastic products, it tends to melt and liquefy upon heating, but once ignition has occurred, it will sustain vigorous flame spread over a surface.

SK- In terms of fire risk, what tool(s) used to make my projects are the most dangerous?

JS- Every year, the National Fire Protection Association (NFPA) compiles statistics gathered by fire departments for the U.S. Fire Administration on the suspected cause of ignition of a fire. The one that jumped out at me from your book is the use of a clothes iron for your projects. Most recently produced clothes irons have built-in safety features such as automatic timers for shutoff and, on some models, automatic shutoff if the iron is tipped on its side or soleplate for longer than one minute. Even with these safety features, an average of 318 clothes iron fires occur every year, resulting in over $10 million in damages. My recommendation, then, is to continue to follow safe practice by never leaving unattended a clothes iron that is on.

SK- Finally, would you mind going through my book’s projects and pointing out some fun fire facts relating to them?

11114, Khaja,FA15

JS- I would love to! Since I have yet to conduct a fire scene investigation in a lighthouse, your Lighthouse Dress project inspired me to research famous lighthouse fires. Some of the first lighthouses were built with a “core” of brick and concrete. Wood was used to build up the exterior of the lighthouse and provide for a means to access the top of the lighthouse where the light was located. One of these lighthouses was built on Eddystone Rocks, south of England. This particular lighthouse was named Rudyard’s lighthouse, which was actually the second lighthouse built as the first was washed away in a large storm. The second lighthouse was constructed in 1709 and lasted until 1755 when the lantern at the top caught fire and spread through the wooden walls of the structure. The three keepers of the lighthouse fought the fire with buckets of water, but were unsuccessful at saving the structure. Luckily, they were rescued by boat and survived the fire.

11114, Khaja,FA15

Your typewriter project was of interest as well, as I have yet to come across a fire investigation case where a typewriter was deemed to be the cause. The best I could come up with was this video I found on Youtube:


I am still not completely certain as to why you would ever want to burn a typewriter.

11114, Khaja,FA15

I couldn’t help but notice your references to the classic movie, Office Space, in your red Swingline stapler project. Swingline staplers are made from plastic and can burn, but a single stapler on your desk or in your home office is not considered a great fire hazard due to the significant amount of metal in the construction and when loaded full with staples. If we stored 1,000’s of them in a warehouse… well that is a different story. While we are on the topic of Office Space and if you are interested, the machine that gets taken to a field and destroyed by the office employees would burn nicely (i.e., it is made from plastic) whether you believe it was a fax machine, printer, or fax machine/printer combo.

11114, Khaja, FA15

My children have always been interested in learning about dinosaurs, maybe even more so than when I was their age. Your prehistoric portrait project begs the question that my children would ask. Did the dinosaurs have to worry about fire? The answer is a resounding yes, and, unfortunately, they were not well prepared to fight fire. Dinosaurs would have had to deal with fires as a result of volcanic activity, lightning, and earthquakes. Any of those mechanisms would have had the potential to initiate wildfires in the prehistoric world. Dinosaur skin may have been slightly more resistant to burn injury than our skin, but without advanced warning of an approaching wildfire, the dinosaurs were at a distinct disadvantage.

11114, Khaja, FA15

My final thought was about your 8-bit bird project. Believe it or not, one of the world’s most renowned arsonists was a bird. I came across the story of this bird a few years into my career. According to the story, a bird was accused of bringing a smoldering cigarette back to her nest, which just so happened to be in the post of a wooden front porch of a house. The cigarette started a smoldering fire in the straw of the nest, which broke out into the connecting space between the porch and the house. Fortunately, the house had minimal damage, and no one was hurt. What happened to the arsonist bird you ask? Well, she remains unidentified and is still at large to this day. Hopefully, she has learned not to use materials that can start a fire to build her nest!

SK- Well, my brain is officially smoldering from all this amazingness that you’ve now fueled it with. I have to say, you really do know how to set a blog post ablaze with flare. Plus, I know these were hot topics that I was simply burning to ask, so I’m thoroughly stoked that you’ve taken this time to shed some much needed light on the situation. You have really sparked some great ideas here. Really and truly, you’ve made my tour more scintillating. Searing perspective. It’s really warmed my hearth. I’m sure you’re scorched from all my puns. Am I getting hot yet? No rapid fire response needed, I’ll stop with the third degree. And also the puns. Maybe. Okay, never.

JS- Thank you for the opportunity to answer your and your audience’s questions SK. It has been a great pleasure having you on the Fire Science Blog.

And, now for the contest! The rules are simple. To be entered into the random drawing to win a copy of SK’s new book for yourself or as an awesome gift for friend or family, simply answer this question in the comment section of this post: What fire hazards related to sewing and fabrics do you experience in your home or place of work? (If we did not touch on it in this interview, it could be the topic of a future post.)

Fine Print: Only one entry will be given for each individual so please only submit one comment per person. One book per winner. Open internationally, however if winner lives outside of the US, they will receive a promo code to purchase the ebook version free of charge. US winner will receive a hard copy. Winner will be chosen from all entries at the close of the tour on Monday, October 26, 2015.

Good luck in the contest and please check out the rest of the blogs on the Sew Adorkable book blog tour!

9/14/15 C&T Blog
9/16/15 Generation Q Magazine
9/18/15 Sew Timeless
9/21/15 Fire Science Blog (Thank you for visiting!)
9/23/15 Art School Dropout
9/25/15 Craft Buds
9/28/15 Pellon
9/30/15 Crafty Planner
10/2/15 Modern Handcraft
10/5/15 Imagine Gnats
10/7/15 May Chappell
10/9/15 Nancy Zieman
10/12/15 Dritz
10/14/15 Spoonflower
10/16/15 Sew Sweetness
10/19/15 Aurifil
10/21/15 Accuquilt
10/23/15 Schmancy Toys
10/26/15 Samarra Khaja


by: Jason A. Sutula


According to the 2014 Edition of NFPA 921 – Guide for Fire and Explosion Investigations, “The boiling liquid expanding vapor explosion (BLEVE) is the type of mechanical explosion that will be encountered most frequently by the fire investigator.” NPFA 921 provides a good basic description of how a BLEVE occurs. In general, a BLEVE event will begin when a container that is filled with a liquid undergoes an insult that results in the rupture of the container. The rupture can be caused either thermally or mechanically. In the thermal case, the heating of the container is responsible for the mode of failure. In the mechanical case, the container rupture is due to an impact or other event that causes a portion of the container to be breached. When the container is breached, the vapor of the liquid expands while the liquid becomes superheated. The superheating of the liquid results in the boiling of the liquid. Additionally, a pressure wave will be generated at the time of rupture and release, which can lead to the fragmentation of the container and the production of missiles. If the liquid in the container is flammable, a premixed system of fuel and air will develop and result in a fireball [Abbasi and Abbasi, 2007]. The Youtube video shown above is one that I show to my students to demonstrate the awesome power of the BLEVE.

One of the most famous BLEVE events took place in Crescent City, Illinois on Father’s Day, June 21, 1970. A freight train with 109 cars derailed. Ten of the rail cars were tank storage cars each carrying 34,000 gallons of liquefied propane gas. At the start of the derailment, one of the liquefied propane gas cars collided with another, tearing a large rupture into one of the other tanks. The result was a large initial fireball and subsequent sustained fire. Five of the liquefied propane gas cars achieved a BLEVE in the first four hours.

According to an excellent article by Robert Burke that was published by Firehouse in 2010 (, twenty-five homes and sixteen businesses were destroyed by fire. Three homes were destroyed by “flying” tank cars and numerous other homes received damage. More than $2 million in property damage occurred as a result of the derailment, fires and explosions along with six fire trucks [Burke, 2010].

It can be hard to put into perspective this amount of damage and how massive the fire and fireballs from the explosion were. After digging around on Youtube, I found the following video that shows actual footage of the Crescent City event. This particular video is narrated in Russian, but still clearly shows the magnitude of the event and the dangers of a BLEVE to both citizens and fire service personnel.



Abbasi and S. Abbasi, “The boiling liquid expanding vapour explosion (BLEVE): Mechanism, consequence assessment, management,” Journal of Hazardous Materials, no. 141, pp. 489-519, 2007.

Burke, 2010,

by: Jason A. Sutula

The (cliché?) saying, “It’s not what you know, it’s who you know,” comes to mind as I write this short blog post. Mostly because I have the good fortune to know Samarra Khaja. Besides being family and a friend of mine, she is a highly talented and creative individual. While having her husband and family over for a visit recently, she spent some time working with me on a new branding image for the blog. The final result is below. If anyone who reads this blog has a need for logo & branding work, illustration, or photography (and several other creative services), I hope you will consider contacting SK. You can check out her work at

And now, the reveal:

Logo low res

Feel free to chime in on the design in the comment section. If there is enough interest, maybe I will make up some t-shirts and give them away in a contest!

by: Jason A. Sutula

This past Friday, Sara Caton presented an excellent take on the potential electrocution risk to fire service personnel when encountering a roof-mounted solar array during an active fire event. Her post raises several good points that must be accounted for in both the training of firefighting personnel as well as understanding the interaction between a solar panel installation and the building construction elements below it.

As a follow up to her post, I received a comment from Professor James (Jim) Milke, Chair of the Department of Fire Protection Engineering at the University of Maryland. Professor Milke reminded me that Rosalie Wills led a group of students that put together a report for the Fire Protection Research Foundation (FPRF) on the hazard assessment of commercial installations of roof-mounted solar panels. The report highlighted a range of environmental exposures in addition to the more common discussion of the performance of the array when involved in fire.

Structural loading, wind loading, hail, snow, debris accumulation, seismic activity, and the hazards of fire are all addressed within the report. A common theme among many of the hazards that were assessed was the idea that the weight of the solar array is not negligible. A photovoltaic array is commonly mounted on to a typical roof assembly that was not originally designed to account for the additional loading of the array. While the roof assembly can support the loading of the array in normal conditions, wind loading, snow loading, and loading from other debris accumulation can cause stresses within the roof assembly over time.

When fire is added to the equation, the increased structural loading on the roof assembly can cause more rapid failure and collapse, especially if an interior fire exposes the roof members directly below the area where the solar array is mounted. Destruction of the supporting building construction under the solar array will cause damage to the electrical distribution system from the array to the structure leading to the development of the electrical hazards to firefighters as discussed in the previous post.

The model building codes have developed new provisions that address some of the hazards analyzed in the FPRF report. The 2012 edition of the International Building Code (IBC) requires a solar array system to have the same fire class rating as the roof assembly. Additionally, Underwriters Laboratory (UL) Standard 1703 (Standard for Flat-Plate Photovoltaic Modules and Panels) was updated with additional testing methods to be able to account for a roof mounted photovoltaic fire class assembly rating. Finally, NFPA 70, the National Electric Code (NEC), has included many provisions within the latest edition to limit the potential of an electrical failure of a photovoltaic system. Progress in the fire safety and minimization of the hazards of these systems continues to be made.

If interested in more information, take the time to watch today’s embedded YouTube video. This was created by the NFPA, and Ken Willette does a good job of pointing out the resources available for fire safe installations of photovoltaic systems.

by: Sara Caton

Sustainability, green technology, and clean energy are all trends that are found at the forefront of engineering and design in today’s world. Because of society’s focus on sustainability, photovoltaic (PV) panels, which use sunlight to generate electricity, are increasingly popular renewable energy systems. In 2013, PV installations in the twenty-four countries that make up the International Energy Agency (IEA) Photovoltaic Power Systems (PVPS) Program combined with non-IEA PVPS countries totaled approximately thirty-nine to forty gigawatts. This total is the highest installation value ever for PV, with a growth of about 35%. (Photovoltaic Power Systems Program, 2014) Although the installation of PV systems increased in 2013, the total investments in renewable energy actually decreased. This can be attributed to the cost reductions of solar PV installations. (Global Trends in Renewable Energy Investment, 2014) The IEA PVPS Program findings and the decreased installation costs emphasize that the use of PV panel systems is a global trend that will continue to grow.

I am completely on board with these PV installation trends, because I believe it is an easy way for people to incorporate the use of solar energy in their lives. PV systems provide great benefits to the environment, which is why the installation of them is so popular; however, these systems can pose great dangers and threats, especially during a fire event. A building that has a PV system installed on the roof may experience increased building loss during a fire compared to a building without a PV system, and the emergency responders are faced with new and different dangers during a structure fire that has a PV panel system. These are concerns that fire protection engineers need to be aware of in order to better protect buildings and people from fires that involve buildings with PV installations.

Lessons can be learned from fire incidents that involve PV panel systems. A fire occurred in a chemical manufacturing facility in West Berlin, NJ that, according to officials, was caused by propane tanks igniting and causing multiple small explosions inside the facility. (Glover, 2014) Dozens of rows of PV panels were installed on the roof of the building, making matters worse. When water was sprayed onto the roof from above, it collapsed. “Firefighters were forced to knock down an outer wall of the facility to expose the collapsed solar panels as well as to fight flare-ups.” (Glover, 2014)

From this example, it is illustrated that building loss and damages can be severely increased during a fire in a structure that has a PV system installed on the roof. The PV system adds a dead load to the roof and can be affected by other external loads caused by the elements. These added loads could be part of the reason the roof was not able to withstand the water jets. Since the PV panels posed an electrocution threat to the firefighters, they had to find alternative options to approaching the fire, which resulted in this example by taking down an exterior wall. This action also increased the amount of damage to the building.

I think it is important to investigate and ask questions about fire incidents that involve PV panel systems to learn how to avoid these dangerous fires and how to protect the emergency responders from these new threats. The two main dangers that these fire pose to emergency responders are electric shock due to direct contact with energized components and electric shock from water-based fire suppression. If energized components are exposed because the protective covering of the panels break due to the fire or fire fighting techniques, the fire fighter can receive an electric shock from direct contact. Because it is impossible to fully de-energize the components of the PV systems and water is conductive, using water for suppression without the threat of electric shock becomes difficult.

There has been research done that suggests safe distances for water application and nozzle spray types, appropriate insulated gloves for firefighters, and the use of tarps to help de-energize PV components. In my personal opinion, more research needs to be done to develop adequately safe fire boots that will help the firefighters avoid electric shock. The table below shows that tests conducted at UL found that aged boots do not perform well in response to shock. Firefighters’ boots generally have conductive metal toe and sole plates to protect the foot, but this conductivity can be a danger when dealing with energized electrical components (Backstrom, 2011). In order to not negate the benefits PV systems provide for the environment, it is vital for fire protection engineers to ensure the safety of firefighters who may be faced with fighting PV system fire incidents.


Backstrom, 2011: Robert Backstrom and David Dini, Fire fighter Safety and Photovoltaic Installations Research Project, Underwriters Laboratories, Inc., November 29.

Global Trends in Renewable Energy Investment, 2014: Global Trends in Renewable Energy Investment, Frankfurt School of Finance and Management, 2014.

Glover, 2014: Sarah Glover and Vince Lattanzio, “Fire Destroys NJ Chemical Manufacturer’s Facility,” NBC News, May, 2014.

Photovoltaic Power Systems Program, 2014: Photovoltaic Power Systems Program, “Trends in Photovoltaic Application 2014,” International Energy Agency, 2014.

by: Adam Dodson

aviation fire investigationThis past summer I had the good fortune of being able to intern at Boeing Commercial Aircraft in Seattle, Washington. In addition to falling in love with the Pacific Northwest and landing a full time job as a MP&P Flammability Engineer after graduation, I was able to learn much about past aviation fire incidents. More specifically, I learned about how these accidents shaped the current state of aviation fire safety.

On July 17th 1996, a Boeing 747-131 Trans World Airlines flight 800 crashed into the Atlantic Ocean off the coast of New York. All 230 people on board were killed in the crash. There was an explosion in the plane’s center wing fuel tank, which caused an in-flight break up of the plane. The energy that caused the ignition of the fuel was determined to most likely have come from a short circuit in the wiring in the fuel quantity indication system. The center wing fuel tank was expected to have flammable liquid inside, but it was also expected to have no ignition sources. As a result of this accident, the FAA imposed additional regulations on fuel tanks. This included a requirement for inert gas systems in fuel tanks to reduce the flammability of possible fuel vapor/oxygen mixtures. Injecting inert gases such as Argon into fuel tanks was shown to reduce the flammability of the vapor mixtures.

On June 2nd 1983, a McDonnell Douglas DC-9-32 Air Canada flight 797 experienced a lavatory fire while on its way from Dallas to Toronto. The lavatory circuit breakers had tripped, but were reset by the pilot, who thought nothing of it because this happened from time to time and was not considered an emergency. This resulted in an electrical fire breaking out near the lavatory. The flight crew attempted to flood the lavatory with a carbon dioxide extinguisher and thought the fire may have even been put out due to the lack of flames. The fire, however, was not extinguished and continued to grow and breach into the cabin. The plane made an emergency landing, but reached flashover conditions less than 90 seconds after the start of the evacuation. It is likely that incoming oxygen from opening the doors for escape helped the fire grow exponentially. 23 of the 41 passengers died from smoke inhalation and burns from the fire. Notable recommendations to the National Transportation Safety Board after the incident included expediting actions to require smoke detectors in lavatories, using advanced suppression agents such as Halon, emergency track lighting to the exits, and changing crew procedures to more aggressively pursue potential fires.

On August 19th 1980, a Lockheed L-1011-200 Tristar experienced a cargo fire shortly after takeoff from an unidentified source. It took the passengers who smelled smoke four minutes to warn the crew and pilot who then turned the plane around for an emergency landing. Emergency personnel did not board the aircraft for 23 minutes after the engines had been shut down because they had a difficult time getting the doors open. When emergency services did open the doors, they found that everyone on board had died of toxic smoke inhalation. It was assumed that most passengers were incapacitated on landing as all the main cabin doors were still shut and the aircraft was still pressurized. As a way to increase the time between flame ignition and evacuation of the airplane, new flammability tests were required as a result of this accident. The Oil Burner test, which tests flame and heat penetration through the cargo liner walls, is one such flammability test.

Finally, On May 11th 1996, a ValuJet Airlines DC-9-32 crashed into the everglades after departing from Miami airport. There was a fire that originated from an improperly contained chemical oxygen generator. This was stored in a class D cargo compartment that was not required to have fire detection or suppression. Rather, it relied on flame resistant materials and being airtight to minimize risk. Unfortunately, the chemical reaction in the oxygen generators was exothermic, meaning it produced oxygen and heat, which was enough to cause a fire that could burn through into other compartments. The fire grew and disabled the control cables in the back of the aircraft, giving the pilots no control. All 210 people on board died in the ensuing crash. Swampy conditions made it difficult for rescuers and the clean up crew to enter the area because of the water and threats like crocodiles and disease. This accident led to increased FAA regulations that required all class D cargo compartments to be upgraded to class C, meaning they were required to have fire detection and suppression systems installed, ventilation control, and a means to exclude smoke, flames, and extinguishing agent from crew areas.

As tragic as these events are, they allowed aircraft manufactures the opportunity to learn how to make aircraft more fire safe. Significant progress has been made in making aircraft more adequately protected from fire, which continues to this day. I am excited to be working toward continuing this trend when I graduate and get the opportunity to use my fire protection engineering degree to make aircraft even more fire safe.

by: Jason A. Sutula

Last week, I enjoyed an excellent presentation by a colleague on the explosive power of combustible dust. The presentation started off with several case studies throughout history that all told a similar tale. One of the most interesting cases was also one of the earliest on record: “The Account of a Violent Explosion which Happened in a Flour-Warehouse, at Turin, December the 14th, 1785, to which are added some Observations of Spontaneous Inflammations.” (Printed in its entirety in Eckhoff, 2003) Even more interesting was that this incident was investigated by a local official, Count Morozzo, who took the time to do as scientific of an investigation as was possible for his time. He even wrote an account of his findings.

According to Count Morozzo, at about 6:00 p.m. an explosion took place in the house of Mr. Giacomelli, a Baker in the city of Turin. The explosion was powerful enough to blow out the windows and window frames of the building, and produced a noise that was as loud as a “large cracker.” At the moment of the explosion, Count Morozzo reported that a very bright flame was observed that only lasted for a few seconds. Further investigation revealed that the “inflammation” had started in the flour warehouse, which was located in the rear of the structure over top of the bakery shop. A boy was stirring flour in this area while using the light from a lamp. As a result of the fire, the boy sustained burns to his face and hands, and his hair had been burned off.

Without the benefit of chemistry and modern fire and explosion dynamics, Count Morozzo was able to use logical arguments to piece together many of the components that led to the incident. He correctly deduced that the flour needed to be in the air (dust suspended in air), that atmospheric air was mixed with the flour (oxidizer), that the event was confined within a small room in the bakery (confinement of the dust cloud), and that the ignition occurred from the light next to the boy (heat source for ignition). These are four of the five components necessary for a dust explosion to occur. The remaining component is the dust itself (the fuel). Count Morozzo was unable to link this component to the event because fuel chemistry was not understood at the time, and he believed that “inflammable air” was confined within the flour and could be released without changing the makeup of the flour itself.

The good news is that the boy recovered from his injuries within a fortnight (14 days). The bad news is that even with Count Morozzo’s account, the process industry did not learn from these types of case studies until more recently in the modern era. It can also be argued that there is still plenty of work left to do today.

In an effort to demonstrate what that poor boy in Mr. Giacomelli’s Bakery must have experienced, take the time to watch the above YouTube video. Mythbusters produced this non-dairy creamer cannon demonstration for Season 07, Episode 03. It is the perfect visual for understanding the power of a dust explosion.

Eckhoff, Rolf, Dust Explosions in the Process Industries, Third Edition, Boston, Gulf Professional Publishing, 2003.