by: Elizabeth Keller


Everyone is aware of the benefits of professional licensing for Fire Protection Engineers; however, few people consider the cost (time and money) for maintaining licensure.  Although the benefits far outweigh the costs, there is an opportunity for improvement in the licensing system that would greatly streamline license maintenance.

A professional engineer must meet the engineering licensure requirements in each state in which the professional engineer seeks to practice.  Most states allow licensure by comity if a professional engineer is already licensed in another state with requirements at least equal to those in the state in which licensure is being sought.  Fire Protection Engineers are always in demand and are increasingly crossing state lines and finding the need to be licensed not just in one state, but in many.  Sounds great, doesn’t it?

The issue is that most states require continuing education prior to the renewal of an engineering license.  Continuing education requirements are not uniform across the states and unlike the more streamlined comity application process, very few recognize the requirements for continuing education via comity.  Renewal periods range from annual to triennial, and the number of continuing education hours ranges from zero to thirty-six (36) or more per renewal period.  It is up to the licensee to keep track of their continuing education hours (also called professional development hours in some states) and to present a log of activities to the licensing board upon request.

Imagine being licensed in more than ten states.  No two of your licenses expire in the same month and different requirements must be satisfied for each.  How do you balance that?  Do you fulfill the requirements of the most demanding state and know that the others are then taken care of?  Unfortunately, it’s not that simple.

Not only do different states have different hour requirements, they also have specialty requirements, such as the need for “live” training, multiple categories for activities with specific limits on each category, and requirements for state specific courses in ethics and rules and regulations.  You could complete all of the continuing education activities required for one state, and still only be halfway to completion in another state.

So why are all of the requirements different?  Well, the simple answer is that’s just the way it is.  Professional licensing boards are all made up of representatives from the state they represent.  They are empowered by the laws of their state and they research, propose, and vote on amendments to their regulations on a state board basis.  Although one state may look at another’s process, there is no real crossover.

What about NCEES you ask?  The National Council of Examiners for Engineering and Surveying (NCEES) published model Continuing Professional Competency (CPC) Guidelines in 2008 for the use of state licensure boards in developing state specific requirements for continuing education.  Many pieces of the NCEES CPC guidelines can be found in state laws and regulation across the country, but boards can pick and choose the pieces that ultimately become incorporated.  If all states used the NCEES CPC guidelines, it would even the playing field and make complying with continuing education requirements a much simpler process.

One idea that could easily streamline this process is a national licensing board for engineers.  Currently, NCEES plays a large role in the licensing of engineers for every state and every prospective engineer generally follows the same four major steps:

  1. Earn a degree from an ABET accredited engineering program.
  2. Pass the Fundamentals of Engineering (FE) exam.
  3. Gain acceptable work experience (typically a minimum of four years).
  4. Pass the Professional Engineer (PE) exam in the appropriate discipline.

What is the benefit to having each state manage application approval when a national council is really managing the application process?  Perhaps the benefit is in the details, but this is not certain.  This is a debate that has many sides and deserves more research.

Overall, the professional engineering licensure system could be well served by a reset and reboot.  As more states adopt continuing education requirements and more engineers cross state lines in the name of business, a better and better case can be made for the development of national guidelines and somewhere in the future, perhaps even a national licensure board.

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: Nathan Pascale


When analyzing the effect of toxicants, there are a few trains of thought that we must consider. First, there are the biological effects. How does the human body process the harmful byproducts that are be produced during a fire and how effectively can it do so? This perspective looks exclusively from an organic point of view, only taking into account functions within the body. The second consideration is for behavioral influences. At a micro scale level, this could be linked to the biological effects as far as how the toxicants can debilitate the brain’s capacity to function normally. However, in taking a big picture point of view this can simply be defined as changes in an individual’s decision making and the actions they take as a result of the toxicants. Finally, in the grand scheme of a fire scenario, we can look at how these biological and behavioral variations can affect the overall tenability analysis of a particular building.

As mentioned previously, the main concerns when determining the tenability of the building are the time to impair one’s ability to escape in a timely manner and the time to incapacitation. The time to impair can be correlated to the behavioral consequences of toxicants in a fire. While the panic theory has been largely debunked, a normal individual is still expected to require time to perceive, recognize, respond, and move to a safe area, and this is all without the effect of toxicants. When we introduce that extra layer of complexity, the question of how much time is enough time becomes much harder to answer. There are many factors that vary on an individual basis that can affect the way they react to the problem at hand, one of them being age.

While irritant gases are important to consider in any fire scenario, their effect is very difficult to quantify due to differing opinions in the field and overall lack of data. Thus, for the sake of this argument, I will focus on narcotic gases. Unlike irritant gases, the lethal and incapacitating effects of narcotic gases are much more accessible and quantifiable through research on animal exposure as well as posthumous studies of fatal fires. Narcotic gases act primarily by attacking the nervous system and to a lesser extent the cardiovascular system. The result is a lethargic state, coupled with headache, nausea, or poor physical coordination, followed quickly by incapacitation or death once the body can no longer compensate for the lack of oxygen being supplied to the brain.

Carbon monoxide (CO) is a toxicant present as a byproduct of all fires. Many deaths have occurred due to CO inhalation where the victims are asleep or inactive for a duration of time before becoming aware of the danger. A model developed by Professor David Purser in 2008 showed that active subjects with greater respiratory minute volume (RMV) rates were much more susceptible to the effects of CO than subjects at rest. When an individual is remote from a room of origin that has undergone flashover, toxicants are inhaled while in a sedentary state until the danger is recognized. At this moment, the exposed individual tries to escape, at which point the effects of the increased respirations an environment laden with CO begin to cause severe impairment or incapacitation.

Elderly individuals are also more likely than the average adult or child to have conditions such as asthma or coronary artery disease. A study conducted by the EPA in 2000 determined that the tenability limit of carboxyhemoglobin (the amount of CO in your blood) for an individual with coronary artery disease is only 5%, while the limit for an average adult is 30% (Purser 2008) and 25% for a child (Klees 1985). Additionally, according to an SEFS report, elderly individuals are expected to spend more time in their bedroom then adults and children. The fact that elderly people are more vulnerable due to physical condition, preexisting health concerns, and that they spend more time in the bedroom environment when exposed to fire conditions, we can conclude that elderly individuals comprise the age group at the greatest risk of death and injury when faced with narcotic gases.

In conclusion, there is evidence to prove a correlation between the effects of toxicity and age, but not enough to reliably quantify what those effects are. Preexisting illnesses, physical conditions, familiarity with the building, and susceptibility to toxicants are just a few of the factors that have to be taken into account during a tenability analysis. Unfortunately, due to the harmful nature of toxicants, experimental studies on humans are considered unethical and there is not a large pool of data to analyze for effects on past fire victims. Thus, with the information currently available, the elderly population can be considered most at-risk in a toxicant exposure event, followed by children, and then adults. Consequently, it is my hope that code committees and the fire protection community as a whole takes a closer look at these factors and evaluates the possibility of increasing the required safe egress time, whether it be by decreasing the walking speed, increasing recognition time, or otherwise, for those occupancies and buildings that shelter a large number of elderly people or children.


Purser, D.A., “The Effects of Fire Products on Escape Capability in Primates and Human Fire Victims,” International Association for Fire Safety Science, 2008.

Klees, M., Heremans, M., and Dougan, S. “Psychological sequelae to carbon monoxide intoxication in the child,” Sci. Tot. Environ., 1985.

Gann, R.G., J.D. Averill, K.M. Butler, W.W. Jones, G.W. Mulholland, J.L. Neviaser, T.J. Ohlemiller, R.D. Peacock, P.A. Reneke, and J.R. Hall Jr., “International Study of the Sublethal Effects of Fire Smoke on Survivability and Health (SEFS): Phase I Final Report,” National Institute of Standards and Technology, August 2001.

by: Michael Harris

There are many methods that fire protection engineers can use to calculate egress time. One popular method taught is hand calculations that are based off of fluid dynamics (these can be done on a computer also). Unfortunately, this method does not take into account human behavior. There are many factors in a fire that can affect human behavior and egress time. One big factor is the toxic smoke produced by a fire.

Tadahisa Jin and Tokiyoshi Yamada (Jin and Yamada, conducted an experiment in Tokyo, Japan on the effects of human behavior in smoked filled corridors. This study attempted to produce as accurate results as possible by using 31 human subjects, aged 20 to 51, as oppose to animal subjects that previous smoke inhalation studies had used. The experiment was done in a straight corridor that was 11 m long, 2.5 m wide, and 1.2 m high. Certain stopping points were arranged in the corridor where the occupants were meant to stop and answer a simple arithmetic question. While in the corridor, the subjects were exposed to different levels of smoke and radiated heat. The inside of the corridor was also illuminated with fluorescent lamps.

To protect the subjects, a 16 layered towel was positioned on their nose and mouth. This provided a filtration of approximately 90% of the smoke from the environment. Additionally, the subjects had no prior knowledge of the corridor before, but were told it was a straight corridor with an end and that they could turn around at any point.

The study resulted in 17 of the subjects reaching the end of the corridor. Fourteen of the subjects had to turn around before reaching the end. An additional finding was that the subjects answered the arithmetic question incorrectly at a higher rate when the smoke density was higher. This correlation was almost linear. Finally, the subjects’ correct answer rate increased as they walked farther into the corridor. The experimenters concluded that this effect was due to the subjects becoming more emotionally stable as they acclimated to the controlled environment.

Jin and Yamada’s study resulted in valuable information that helped to better understand human behavior in a toxic gas environment. Close to half of the occupants decided the emotional toll was too high and decided to reverse direction and retreat out of the smoke filled corridor. It is worth noting that none of the subjects were exposed to a true fire scenario, considering that they only had to walk through a straight corridor and were protected from the toxicity of the smoke. A reasonable inference would be to assume that more of the subjects would have turned around in the corridor if they experienced pain due to breathing in the toxic smoke.

One of the most important findings of the study is that occupants will change their path due to the presence of smoke. This action of changing path can greatly increase egress time, and put the occupants at higher risk of injury or even fatality. Furthermore, the subjects’ cognitive ability decreased with heavier smoke. This decrease was strictly due to the emotional stress of the scenario. In an actual fire, occupants of the structure may lose cognitive ability to the point of not being able to find a safe path out.

The silver lining in this experiment is that the subjects’ cognitive ability was found to increase over time as they acclimated to the environmental conditions. Unfortunately, this observation may be inaccurate due to the limitations of the experiment. The possibility exists in an actual fire that the occupants will be exposed to an increasing dose of toxicants. Furthermore, in many structures, an occupant will not have as direct of an egress path as utilized in the experiment.

It is clear from the Jin and Yamada study that simply using fluid dynamics to calculate the egress time is not enough. Fortunately, many fire protection engineers will add a safety factor to help account for limitations such as human behavior. My hope is that future research will eventually give our community better insight into human behavior in fire, and allow for a more quantitative approach to the design of fire safe egress.

Jin, Tadahisa, and Tokiyoshi Yamada, “Experimental Study of Human Behavior in Smoke Filled Corridors.” Fire Safety Science-Proceedings of The Second International Symposium, pp. 511-519, 1989.

by: Jason A. Sutula

Most people do not think about metals burning when they think about combustion and fire. Yet, metals can combust, especially when the metals are being used within an industrial process or themselves being processed at higher temperatures. Fortunately for the process safety, mining, and other industries, much research on metal combustion has been done over the years. One of the first studies on the burning of metal dusts was published in 1955 by Titman (Titman, 1955).

Titman examined small metal particles and the influence they had on the explosive mixtures of gases. Additionally, the metal dusts themselves were determined to have explosive properties. The hazards of metal dust combustion are similar in nature to those of organic dusts, which were discussed in a previous post of mine (The Creamer Canon). Since metals have a high affinity for oxygen and have the material property of high heats of oxidation, they are capable of producing high temperatures and the liberation of energy in very rapid fashion.

Another seminal, systematic study was conducted by Harrison and Yoffe in 1961 and published in the Proceedings of the Royal Society of London (Harrison and Yoffe, 1961). Harrison and Yoffe conducted their experiments using wires of various metals. These metals included aluminum, iron, magnesium, molybdenum, titanium, and zirconium.

Harrison and Yoffe demonstrated that the process of metal combustion was much more difficult to initiate when the metal was in wire form as opposed to dust. Their results indicated that the explosive hazard associated with the metal dusts were not as much of a concern with larger chunks of metal. Additionally, Harrison and Yoffe discovered that the mode of burning for each metal was determined by the relative melting and boiling points of the metal and the metal oxides (which is formed as the product of the combustion reaction).

Today’s embedded YouTube video selection demonstrates the energetic reaction produced by titanium powder burning. The reaction of the individuals involved is eerily similar to that of the Mythbusters crew as seen in the Creamer Canon video. In addition to providing a means to educate us through videos on the internet, combustible metals do have many other useful purposes. One such is the use of metal dusts to ensure a specific color in commercial firework displays. Titanium, Aluminum, and Magnesium powders are used to make a vibrant white color in the pyrotechnic stars. With that in mind, an argument can be made that the Chinese were actually the first researchers who began walking the path of understanding metal combustion. Have a happy and fire safe 4th of July!

Titman, H., Trans. Inst. Min. Engrs., Lond., 115, 1955.

Harrison, P.L., and Yoffe, A.D., “The Burning of Metals,” Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences, Vol. 261, No. 1306, pp. 357-370, 1961.

by: Raquel Hakes

Wildfires. I want you to stop and think a moment. When I say that word – wildfires – what comes to mind? Maybe if you live in the United States, you think of the West. Maybe the word “wildfires” is synonymous with California or Arizona or Colorado. Maybe you are from Australia and mentally translate “wildfire” to “bushfire.” Perhaps you have watched news stories covering major fires or you took your kids to see the Planes: Fire & Rescue movie and that is really your only familiarity with the idea of wildfires.

I have lived in the East for over a decade and a half now, but I still go back to Arizona to visit my father’s family. They live far down south, close to the border with Mexico, near a mountain range. One year, I arrived, and the mountains were black. Everything along the side of the roads was black. I had followed the news on the wildfire closely from across the country, but seeing the devastation first hand was another matter. The Mexican restaurant that had stood a few miles down the road from my cousin’s house for several decades was gone. They planned to rebuild, but never managed it. We woke up to go hiking one morning, but the park we wanted to visit was closed. There was too much damage; downed trees, burned vegetation, blocked roads, and erosion. My cousin’s house was safe, but when I left, I could not help but wonder if the house would still be standing if the fire had been closer.

Even something as relatively small as a house fire probably seems far from manageable. You have your smoke alarms and maybe sprinklers. You try to clear paper away from your fireplace. You hope you remember to turn off the stove when you leave the house, and you extinguish your candles before going to bed. There are little things you can do, but once a fire starts, the task of extinguishing it can be overwhelming and most likely impossible for you. You have to leave it up to the firefighters and hope.

What about when a fire is so much bigger? What about when the forest or grassland around your house is on fire? Or you go to sleep, and it looks like the mountains are burning? And what if none of this has happened to you yet? Maybe you know that it is possible – not just out West, but many places – for a wildfire to occur.

Many people are not sure what to do if they live in a place with wildfires (for those in the U.S., these places do include Maryland, Florida, Massachusetts… it is not just the West). Perhaps they do not know the risk or, if they do, they do not know what effect their actions could have. If that is you and you are wondering, I have some good news: there are things you can do to keep your house safer, all of which are easily manageable.

Here 6 ways you can prepare for a wildfire:

  1. Find out your risk– This is a combination of how often wildfires occur in your area, how severe they can be, and how protected your house is or is not.
  2. Clean your gutters– This is a major way fires can start at your house from a wildfire! Firebrands, basically embers or coals, can fly out from the fire and land in your gutter or other places around your house. If you have a bunch of stuff in your gutter, it might catch fire and spread to the rest of your house.
  3. Rake your leaves– This follows along from point #2. Move the dry leaves (very flammable) away from your house. Even if you only rake them a few feet away, this can make a huge difference.
  4. Do not put your woodpile (or mulch pile) right next to your house or under your deck– Imagine the biggest bonfire you have been to. Would you want that next to your house? Probably not, so move it out further in your yard or into your shed.
  5. Plant smart– Some plants are more flammable than others. For example, plants that produce a lot of dead branches can catch on fire more easily. Junipers, hollies, and other coniferous plants are fairly flammable. Plant things that will not burn as easily, such as deciduous plants. If you are not sure what plants burn, a quick internet search gives a myriad of helpful results.
  6. Educate yourself– There are tons of resources out there for you, put out by the NFPA, Ready, Set, Go!, local fire departments, departments of natural resources, and more. Start looking and keep yourself safe!

What does the word “wildfire” mean to you? Maybe it still means a faraway place and maybe it means close to home. Maybe it reminds you of friends or family that have experienced a wildfire. Whatever the answer is, I hope you now understand that you have some control over what happens if a wildfire ever becomes more personal. A few little actions will go a long way to keeping your home safe from a wildfire. Wishing you good weather for raking and cleaning!

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.