NFPA Today

Explosions, Deflagrations, and Detonations

When it comes to things that go boom, terms such as explosion, deflagration, and detonation are often incorrectly used interchangeably. To help clear things up, this blog will go into the technical definitions of explosions, deflagrations, and detonations, as well as the appropriate time to use each term. Explosion An explosion is a sudden, rapid release of energy that produces potentially damaging pressures. When a gaseous fuel fills a space, it needs to mix to a certain air-fuel concentration to create an explosive atmosphere. When an ignition source is introduced into the explosive atmosphere, it creates a flame that travels away from the ignition site and expands the burned gases behind the flame front. When an explosion is confined, it creates a restraint of the expanding gases and results in an increased pressure within the enclosure. When the enclosure ruptures, this is what most people think of when they hear the term explosion. However, explosions don’t always need to be confined. The flame speed in explosions can be quick enough to produce compression waves and cause damage with little or no confinement. The damage potential of an explosion depends on the pressure that is created from the explosion as well as how quickly energy is released from the explosion. Explosions can be either detonations or deflagrations depending on their flame speed.   Explosion A sudden, rapid release of energy that produces potentially damaging pressures. Deflagrations and detonations are types of explosions.   Deflagration A deflagration is an explosion where the flame speed is lower than the speed of sound, which is approximately equal to 335 m/sec (750 mph). Explosives that deflagrate are known as low explosives. The actual speed of the explosion can vary from 1–350 m/s (2–780 mph). Peak pressures produced by low explosives are orders of magnitude lower than those produced by high explosives, and the damage inflicted by low explosives can vary greatly depending on the fuel and confinement. For example, if black powder is ignited outside of containment, it just fizzles, but when it is confined, it creates an explosion that can propel bullets.   Deflagration  An explosion where the flame front travels through the air-fuel mixture slower than the speed of sound   In addition to the black powder example, examples of deflagrations involving low explosives include the ignition of propane gas for a cooking grill and fuel powering of a combustion engine in a car.   Detonation A detonation is an explosion where the flame speed is greater than the speed of sound. Detonations are louder and often more destructive than deflagrations. While deflagration occurs when a fuel and oxidizer (typically air) mix, a detonation doesn’t always need an external oxidizer. Explosives that detonate are referred to as high explosives and have a detonation speed in the range of 2,000–8,200 m/sec (4,500–18,000 mph). High explosives are typically designed to cause destruction—often for demolition, mining, or warfare.   Detonation  An explosion where the flame front travels through the air-fuel mixture faster than the speed of sound   Examples of high explosives that detonate include dynamite, TNT, and C4, a plastic-based explosive.   Learn more Hopefully, this blog helped shed some light on these common terms you hear when discussing types of explosions. For more information on explosions, check out the 21st edition of the NFPA Fire Protection Handbook®, which contains several chapters on the topic, including Chapter 2-8, “Explosions,” Chapter 6-16, “Explosives and Blasting Agents,” Chapter 17-8, “Explosion Prevention and Protection,” and Chapter 18-6, “Deflagration Venting.” The following codes and standards are also related to explosions: NFPA 495, Explosive Materials Code NFPA 69, Standard on Explosion Prevention Systems NFPA 68, Standard on Explosion Protection by Deflagration Venting NFPA 67, Guide on Explosion Protection for Gaseous Mixtures in Pipe Systems If you want to learn more about a specific type of explosion—a dust explosion—check out the following Learn Something New™ video by NFPA Journal®.

New RFP Open for Project to Review Emergency Egress and Rescue Challenges in Rail Tunnels

Next week will mark the three-year anniversary of one of the most significant subway fires in New York City history. At about 3 a.m. on March 27, 2020, a subway train heading north out of Manhattan caught fire as it rolled into the Central Park North–110th Street Station. The blaze killed one train operator and injured 16 other people, while dozens of others had to evacuate the subway. NFPA 130, Standard for Fixed Guideway Transit and Passenger Rail Systems, specifies fire protection and life safety requirements for underground, surface, and elevated fixed guideway transit and passenger rail systems. It also specifies maximum distances for how far passengers would have to travel to egress in the event of an evacuation. But the current language in the standard lacks technical substantiation for distances to point of safety for both 800-ft (244-m) spacing between cross passages and 2500-ft (762-m) spacing between exits and the surface. Additionally, the minimum emergency walkway widths specified in NFPA 130 are based on outdated research that does not accurately reflect current anthropometric data and limits evacuation to single file. To help the standard reflect the most recent technical data, the Fire Protection Research Foundation is now seeking proposals from project contractors to carry out a new project to establish a comprehensive understanding of the impact of changing criteria for both exit distances and walkway width on the probability of successful egress in rail tunnels, as well as the impact of such changes on emergency response capabilities. Researchers will review emergency egress and rescue challenges in rail tunnels through a literature review, case study analysis, evacuation modeling, comparative analysis, and the development of a research plan. More information about the open request for proposals (RFP) seeking a contractor for “Review of Emergency Egress and Rescue Challenges in Rail Tunnels” is available here or on the Foundation’s website. Instructions on how to respond are included in the RFP. Please submit your proposal to Jacqueline Wilmot by April 7 at 5 p.m. ET.

Fire Break

Take Your Community Through the Wildfire Risk Assessment Process

Firewise USA® sites across the country are working hard to improve the resistance of homes and properties within their boundaries to embers and small surface fires that can spread from a wildfire. But how do they know what messages to focus on in their outreach to community members? How do they decide which projects to prioritize? Completing a community wildfire risk assessment is one of the most important steps in the Firewise USA recognition process. The assessment serves as a tool to help residents gain an understanding of their community’s strengths and vulnerabilities by uncovering the conditions of homes and the corresponding home ignition zones within that community. Ultimately, the completion of a community wildfire risk assessment helps communities understand their wildfire risk so that they can start to engage in risk reduction efforts. An image from the Community Wildfire Risk Assessment Tutorial from NFPA shows an example of property strengths and property vulnerabilities.    The recommendations provided by the completed assessment will be the board’s or committee’s primary tool in determining the action priorities within the site’s boundaries. Luckily, the Community Wildfire Risk Assessment Tutorial from NFPA® makes starting the community wildfire risk assessment process easy. The free online tutorial walks people through the risk assessment process. Individuals who complete this tutorial will be able to: ·       Describe how fire spreads throughout a community ·       Explain how homes typically ignite from embers and low-flame surface fires ·       Identify strengths and vulnerabilities of homes and surrounding landscapes ·       Use those skills to complete their own community risk assessment ·       Develop a prioritized, multi-year action plan to reduce the community’s risk from wildfire Complete the tutorial today and help your community get started on its wildfire preparedness journey.

May 6 Is Wildfire Community Preparedness Day. What You Do Makes a Difference.

In just under two months, it will be “that time of year again”—time to prepare your home and neighborhood for wildfire! The annual Wildfire Community Preparedness Day (Prep Day) campaign has begun. For the ninth consecutive year, NFPA® and campaign cosponsor State Farm® encourage everyone to join together on the first Saturday in May for events and activities that can help make homes and communities safer from wildfire. On Saturday, May 6, 2023, people from across the United States and Canada will take part in projects that increase their safety from wildfire. Take the opportunity to defend your home ignition zone by taking simple, low-cost steps along with your neighbors.   NFPA and State Farm make it easier with a Prep Day toolkit. The toolkit is a wealth of project ideas, safety tips, promotional material, and more. While project awards are not part of the 2023 campaign, Prep Day activities bring tremendous value to your community. For instance, Prep Day work can help Firewise USA® sites meet their annual investment criteria for volunteer hours. Engaging in Prep Day can be an important first step for people who want to be safer from wildfire but aren’t sure how to begin. Use the Wildfire Community Preparedness Day Toolkit, videos, social media cards, and other wildfire safety resources at Share them with others in your community to not only make a difference in safety on Prep Day, but to make a difference all through the year as well.

Safety Source

Addressing the True Safety Needs of Your Community Is Key to Reducing Its Leading Risks

At a CRR Kitchen Table event hosted by NFPA® earlier this month, the Gates Fire Department (New York) shared how conducting a community risk assessment (CRA) using CRAIG 1300®, the digital tool that helps capture and analyze community data, helped them identify the leading safety risks within their community and create a plan for addressing them. Alan Bubel, fire chief of the Gates Fire Department (GFD), said that in previous years he spent more time looking at trends across the country, but many of those trends didn’t truly speak to the needs and circumstances of his community. By changing their focus and looking at the real risks and threats, Bubel and his colleagues have been better able to respond to those issues and needs, particularly as demographics have changed over the past 20 years and more residents are at higher risk to fire. “If we don’t know what our community’s needs are, we aren’t going to be able to meet them,” said Bubel. Kalli Herouvis, CRR specialist for GFD, and Laurie Schwenzer, assistant CRR specialist for GFD, also shared their approach to implementing an effective CRR strategy, noting that they look at CRR from both an educational and operational standpoint. As the needs and risks are changing—and the pace of that change is getting faster—the data provided by CRAIG 1300 helps identify those needs and effectively address them. Herouvis reinforced that understanding the people plays a key role in their efforts. “Demographics, the occupancies within the community, economics—they’re are all factors in identifying the risks within the community,” she said. The Gates Fire Department also said that CRAIG 1300 has been an effective tool for substantiating the need for more staffing and services, as the tool effectively tracks the increased number of calls they receive and the reasons for those calls. Consequently, the Gates Fire Department has been able to increase its staffing and, in turn, have been more effective in providing services to the community. The upcoming KT event on Wednesday, March 29, will feature Jason Orellanas from the Cape Coral Fire Department (Florida), who will talk about how the data from his Community Risk Assessment helps not only to guide prevention efforts, but also how it was a valuable resource in the aftermath of Hurricane Ian. Email to register!
2022 Fire & Life Safety Educator of the Year Award recipient Brene Duggins sharing Sparky the Fire Dog® fire and burn prevention messaging with children.

Nominations Sought for 2023 NFPA Fire and Life Safety Educator of the Year

Each year, the NFPA Fire and Life Safety Educator of the Year Award is presented to a fire service educator who takes the lead role in making their communities safer. Since 2000, the Public Education Division of NFPA has presented this prestigious award, highlighting the great work being done in the field of fire and life safety (FLS) education.     RELATED: Read about the 2022 winner here.   This award is given yearly to a North American FLS educator who meets the following criteria:    Works for a local/municipal fire department or fire marshal’s office. Uses NFPA educational programs and materials in a consistent and creative way for their community/audience. Demonstrates excellence and innovation in reaching out to the community with NFPA materials.   The Educator of the Year receives: $1,000 honorarium which recipients can accept or forward to the charity of their choice. Sparky the Fire Dog® statue Paid registration to attend the NFPA Conference & Expo® from June 19–23 in Las Vegas. Additional $1,000 donation to the recipient’s local fire department or the fire marshal’s office to support public education activities.   The nomination period is open through March 28, 2023. To submit your nomination, visit the  NFPA Fire and Life Safety Educator of the Year Award page to download the form and submit the nomination and support materials. Questions can be sent to Follow me on Twitter @AndreaVastis, Sparky the Fire Dog® on Twitter and Facebook, and NFPA on Instagram to keep up with the latest in fire and life safety education.

Fire Sprinkler Initiative

Home Security Video Reveals How Fast a House Fire Can Become Deadly and Why Home Fire Sprinklers Are So Important

We’re all used to seeing doorbell camera social media posts, but I wasn’t prepared for the dramatic security recording I watched this past winter. Nothing illustrates how fast a house fire can become deadly than video shot in real time. And this footage captured every minute of a tragic fire in Millers Falls, Massachusetts. Across the street, a home security camera with a clear view of the front of the burning home left a memorable record of its fast destruction.   According to the Turners Falls Fire Department, the fire started in a room on the first floor at the front corner of the house. From the video, flames can be seen in the window, but even as they grow, passing drivers don’t appear to notice. In less than three minutes, the video shows the fire spread to another room and outside the home, catching the moment flashover occurs. At that point you can hear the windows break and the crackling sound of the growing fire on the camera’s audio. Several occupants were able to escape. Sadly, one person and two family pets did not survive this fire.   The owner of the security camera posted the footage on YouTube and allowed local media to use it to report the story. The Massachusetts Fire Sprinkler Coalition saw the coverage and recognized that the recording provided an important opportunity to use as an educational tool. They remembered that the Home Fire Sprinkler Coalition had created an educational video a couple years back that showed interior security footage of a fire in an occupied room in a home. That video has received more than 2 million YouTube views to date.   The Coalition approached HFSC and together they produced a short video that pairs the Millers Falls security footage with HFSC’s interior video of an actual living room fire, with and without an installed home fire sprinkler. This dramatic new resource will help viewers understand how destructive home fires truly are and the lifesaving difference when a home is protected with fire sprinklers. We encourage you to share this video (below) as part of your outreach activities in your community.       HFSC focuses its educational efforts on installing fire sprinklers at the time of construction. The Millers Falls fire was in an older home and it’s not realistic to expect older existing homes to be retrofit with fire sprinklers. But the fire footage is a real-life example of how fast and dangerous home fires actually are, and why fire sprinklers are required in today’s codes. This video is proof of why every new construction home should be protected.   For more information about home fire sprinklers and to get free resources to share, visit the HFSC website.
A microphone

Two Major Home Fire Sprinkler Advances in Colorado

I’d like to send a loud shout-out to the town leaders of Avon and Erie, Colorado, for scoring huge wins by voting to include home fire sprinklers in their building codes. On December 13, both the Avon Town Council and the Erie Board of Trustees adopted building codes that require all new one- and two-family homes to be protected with installed home fire sprinklers. During the code process in both towns, there was a discussion about passing the code without the fire sprinkler requirement. In response, Erie’s Mayor Pro Tem Sarah Loflin pointed out that sprinkler systems might save multiple homes in an area that’s densely populated. Mayor Justin Brooks added that not having sprinklers would potentially have catastrophic consequences. They and others who spoke in favor prevailed and Erie’s requirement goes into effect beginning April 1, 2023. During a public hearing in Avon, Mick Woodworth, fire marshal from the Eagle River Fire Protection District, which serves the Town of Avon, was also an outspoken advocate. According to Vail Daily News, he said, “We’re community risk management, and if we want to manage the risk in our community, the No. 1 thing is fires — the way we manage that in a home is fire sprinklers.” Avon’s new code will be effective 30 days after approval. We all can learn from the victories in Avon and Erie. They were hard won because of the strong preparation and presentations by their local fire service representatives. Cost inevitably comes up in every hearing. A concern about fire sprinklers affecting affordable housing was raised in Erie. Jeff Webb, fire marshal for Mountain View Fire Rescue, which serves the town of Erie, said that when discussion centered on limiting the requirement to larger homes as a remedy, one trustee provided a very effective counterargument. It would be inequitable to provide safety measures to only those that could afford it. The town should act to make sure all residents purchasing new homes had the same safety features. Just because they were packed tighter to make them more affordable didn’t mean they had to give up safety, when in fact they were at higher risk because they were packed so tightly together. Another excellent strategy in Avon was addressing the role of sprinklers and firefighter health. This is an important point for any sprinkler code hearing and it is essential to have the fire service point of view represented. Besides occupant injury prevention, sprinklered homes protect responding firefighters by controlling fires automatically and keeping them small. These fires are not only less hazardous to fight structurally, but they also produce less toxic smoke. That directly mitigates the problem of responder exposure-caused cancer and other diseases. For more on this, read the FM Global report, which documented that fires in sprinklered homes produce 90 percent fewer carcinogens than in non-sprinkled homes. Discussions in both towns’ hearings drove home the need for better education of all decision makers. If your community does not yet have a building code requiring sprinklers in new homes, strengthen and widen your fire sprinkler outreach now, before future hearings. Reaching your local officials, planners, developers and builders in your community is essential. Above all, they need to know these facts: Today’s unprotected home fires can become deadly in as little as 2 minutes. Homes are where most fire deaths occur. Installed home fire sprinklers prevent injuries, save lives, protect the health and safety of responding firefighters and preserve property. And, most importantly, any home built to today’s codes that lacks installed fire sprinklers is substandard. You’ll be better armed if decision makers have these facts when they are making code decisions. You’ll have less opposition, and they can show their concern for their communities by keeping—or amending in—a new-construction sprinkler requirement. Be aware of your own power. In jurisdictions where home fire sprinklers aren’t in the current code and no update is forthcoming, the authority having jurisdiction (AHJ) and fire marshal should make themselves a regular and vocal presence in the new development pre-planning process to ensure home fire sprinklers are on the table and to include current data and educational content in planning discussions. Tap into our free resources. For helpful safety tip sheets, visit our tip sheet webpage. And for home fire sprinkler content, use HFSC’s free turnkey tools that make it easy for you to educate your target audiences. You can create a space on your website about the value of building new homes with fire sprinklers. Upload videos and other content. Post cards to your social media accounts. Or simply link to – HFSC’s website is free of advertising and all content is free to you.  Bottom line? Home fire sprinklers won’t sell themselves. A vocal, persuasive, tireless leader and activist like you, who exercises your power to influence community decision makers to do the right thing, will protect your jurisdiction for generations to come.

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