Posts Tagged ‘Fire Safety Engineering’

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.

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by: Matthew Gentzel

Mass Notification by Gentzel

Having spent my first semester of college at the United States Air Force Academy, I have been exposed to a lot of mass notification during drills. In general, by using the same systems to communicate information for fire evacuations, as well as other events, organizations have the opportunity to save money, streamline reaction times, and to frequently check that their emergency systems work. On the other hand, they also face the risks of causing confusion if alarms are not paired with specific information and direction (e.g., at the Academy there were many different alarm sounds for different types of threats, but not everyone knew the difference between the tones). Despite these and other possible problems, integrated mass notification systems are likely to be very beneficial, especially when paired with voice notification.

Although technological developments and improvements have affected mass notification systems, much of their implementation has been primarily affected by historical incidents and trends:

“The motivation to expand NFPA 72 to include mass notification and emergency communications systems beyond just fire events was driven by a number of fatal events such as the Khobar Towers bombing in 1996 and the Virginia Tech massacre in 2007. The Department of Defense (DOD), through the United States Air Force, first petitioned NFPA to develop a standard on mass notification in 2003.” [1]

With increases in the trending frequency of mass shooting in the recent years [2], a corresponding increase in mass notification is likely to continue, and to be beneficial to life safety. In a recent 2014 NFPA workshop, a panelist from the Federal Bureau of Investigation (FBI) described the scope of active shooter incidents, and more specifically how they affect schools. In 14 out of 16 studied school shootings, the shooters were students, which indicates a need for mass notification systems that cannot be abused by insiders.

Similarly, a problem was discussed by the panel about the issue of having too much communication. Due to the presence of social media, there is a high likelihood that during an emergency there may be reduced phone service from the high use of personal mobile devices. To prevent this, mass notification to mobile devices should be able to instruct message recipients to only send vital messages so that first responders can communicate situation updates.

Among other data considered, there was discussion of the effectiveness of lockdowns. Lockdowns are security measures taken during emergencies to prevent people from leaving or entering an area, and often involve taking shelter in place. Mass notification provides a rapid means of implementing a lockdown policy throughout a building or area, and can harden potential targets against harm, giving emergency responders more time to react to such situations. Although the median police response time to an active shooter incident is approximately three minutes, having building occupants seek shelter before this amount of time is likely to make a significant difference. According to the FBI, “The five highest casualty events since 2000 happened despite police arriving on scene in about 3 minutes.” [2] Because most of the damage inflicted in an active shooter incident is often early on, reducing the reaction times of potential victims is likely to be one of the highest leverage areas for reducing deaths. Though pre-training methods such as the “Run, Hide, Fight” technique are likely to be most effective, mass notification may play a future role in preventing bystanders from unknowingly entering an area that they are likely to be harmed.

Another type of potential problem for mass notification in the event of direct attack is that an attacker could deliberately send false information. Emergency responders have already dealt with the problem of false alarms and potential traps for years. The new complication of having mass notification is the potential for false information to be rapidly distributed to others. Systems should be designed so attackers cannot access voice notification systems, and so that fire alarms do not give access to secure areas during a lockdown.

Despite the benefits of emergency text alert tones in instances where there is a direct attack, there is the chance that this type of notification could be abused. Since part of the point of a lockdown in an active shooter incident is to make it harder for a gunman to find targets, loud emergency tones could assist such a person in differentiating between empty and occupied rooms. Ultimately, it is up to phone service providers to create the software so alerts can be sent with or without tones.

With over 160 mass shooting incidents recorded by the FBI, there is still a great deal of analysis left to tackle this specific type of problem. Security from an attack is very expensive, so good solutions to these sorts of problems will be dependent upon risk assessment as well as cost effectiveness. Based on the threats that are the most likely and the most harmful, reasonable measures can be taken to increase the resilience of mass notification systems and to streamline their integration with fire alarm systems.

 

  1. “How NFPA 72 Defines Mass Notification.” Facilitiesnet. N.p., n.d. Web. 07 Dec. 2014.<http://www.facilitiesnet.com/firesafety/article/How-NFPA-72-Defines-Mass-Notification–14311>
  2. “Active Shooter Events from 2000 to 2012.” FBI. Web. 7 Dec. 2014. <http://leb.fbi.gov/2014/january/active-shooter-events-from-2000-to-2012>

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 smarrakhaja.com.

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: 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: 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: Jason A. Sutula

In a previous post on the topic of fire in space, I discussed the 1997 fire incident aboard the Mir Space Station. The case study still resonates today and provides valuable lessons for both NASA and the private commercial space companies on what fire hazards can be expected and need to be defended against in both manned and unmanned spacecraft missions. The single most important lesson that the Mir incident taught us is that the process of a fire burning in space is not intuitive.

Gravity, the driving force for natural fluid flow on the earth, cannot exert its influence on people, objects, and even fire when they are in a spacecraft circling the globe. In free fall around the plant earth, hot gases do not rise, and cold gases do not fall. The effects of buoyancy as seen in earth-bound fires are removed, which results in drastic differences in the appearance and structure of flames.

Fortunately, research in these areas has continued over the past few decades. Several on-going research studies are currently being conducted independently as well as in conjunction with NASA and the International Space Station in efforts to more fundamentally understand the fire hazards in microgravity environments.

One study by McGrattan, Kashiwagi, Baum, and Olson (McGrattan et al., 1996) demonstrated some strange fire behavior in microgravity conditions. For the study, a thin cellulosic fuel was suspended in a combustion test rig designed for a 2.2 second drop tower. The 2.2 second drop tower provided of a short amount of simulated microgravity conditions while the fire was burning. Ignition occurred in the middle of the sample and the flame was allowed to spread both vertically “upward” and “downward” at the same time. As a further variable, the researchers forced an air flow across the fuel sample at various speeds. The results were very surprising. The researchers initially expected the flame to propagate more rapidly in the downstream direction of the flow of air (think of how a camp fire will flare up when you blow on the coals). Instead, the fire burned more readily in the upstream or “opposed” direction of the flow, and the downstream flame died out quickly.

McGrattan et al. formulated a two-dimensional, time-dependent combustion model using computational fluid dynamics to better understand the phenomenon. Their computational study demonstrated that the flame moving in the opposite direction to the flow created an “oxygen shadow” in relation to the flame moving in the same direction as the air flow. This resulted in the downstream flame extinguishing since the flame moving toward the flow had already consumed all of the available oxygen!

In the embedded YouTube video above, Dr. Sandra Olson of the NASA Glenn Research Center, presents actual footage of the flame front burning as it is dropped in the 2.2 second drop tower. The full video is geared toward a younger, more kid friendly audience, so if you want to skip ahead, the microgravity combustion video and discussion begins at 0:51.

More research and computational studies will need to be conducted by NASA and commercial space ventures to better understand all of the fire hazard risks associated with microgravity environments. Fortunately, there are pioneers in this field laying the groundwork for fire safety in the final frontier.

McGrattan, K.B., Kashiwagi, T., Baum. H.R., and Olson, S.L., “Effects of Ignition and Wind on the Transition to Flame Spread in a Microgravity Environment,” Combustion and Flame, 106: pp 377-391, 1996.