Topic: Fire Protection Systems

Strobe

Occupant Notification Strategies

A fire alarm system is intended to notify occupants and, often, the responding personnel to an emergency. During the initial stages of the system design, it is important to answer the following questions:  who needs to be notified; what do they need to know; when do they need to know it; where will they be; and why do they need to know? The answers to these questions will determine the most appropriate type of notification strategy. Occupant notification may be in one of two modes, public or private and there are additional options such as selective notification, a presignal feature, and positive alarm sequence to address unique situations. Many of these alternative designs require authority having jurisdiction (AHJ) approval. Public mode Public mode fire alarm systems are what most people think of when they think of a fire alarm. Once an alarm is received from an initiating device, the building goes into alarm, all occupants are notified, and evacuation begins. In NFPA 101®, Life Safety Code® this is the base requirement. Selective notification Sometimes it is impractical for an entire building to be emptied at once. We commonly see this in high-rise buildings where it would take too long for all occupants to evacuate. Therefore, to prioritize the evacuation of the occupants closest to the danger, selective notification can be used in a public mode system. Typically, this strategy allows the fire floor and one or two floors above and below the fire floor to be notified. Then, if the fire continues to progress, additional floors are evacuated. This method minimizes the number of people in the means of egress, allowing first responders access to the emergency, and gives priority to those occupants at highest risk. Per NFPA 101, this type of evacuation strategy is permitted wherever the total evacuation of the building occupants is impractical because of the building’s configuration and where the evacuation strategy has been approved by the AHJ. Many high-rise buildings use this strategy. Private mode A private mode fire alarm system only notifies those concerned with implementing emergency actions. Some situations where it may be permitted include where people are incapable of evacuation, such as hospitals or where people are not allowed to evacuate, such as prisons. For a detailed description of private mode fire alarm systems be sure to read this blog. If you are looking for a more high level overview of public mode vs private mode be sure to check out this blog. Presignal feature A presignal feature allows the initial fire alarm signal to sound only in department offices, control rooms, fire brigade stations, or other constantly attended central locations. The initial signal is also transmitted to the supervising station if there is a connection. After the initial signal, the rest of the system is operated either by a person actuating the general alarm, or a feature that allows the control equipment to delay the general alarm by more than 60 seconds after the initial alarm. These types of systems are permitted in NFPA 72®, National Fire Alarm and Signaling Code® and in NFPA 101 where the specific occupancy chapter allows it and where the initial fire alarm signal is automatically transmitted, without delay, to a municipal fire department and to an on-site staff person trained to respond to a fire emergency. The initial signal also needs to be transmitted to a fire brigade, if one is provided. Although the presignal feature may delay notifying occupants, it does not delay alerting the responding fire department or brigade. An example of an occupancy that allows this feature is existing assembly occupancies. Positive alarm sequence A positive alarm sequence is another option. This option allows delaying the notification of the responding fire department where other trained individuals are available to investigate alarms.  Examples of trained individuals include security personnel and private fire brigades. In a positive alarm sequence, the signal from an automatic fire detection device must be acknowledged by a trained professional at the fire alarm control unit within 15 seconds. Once acknowledged, the trained professional has up to 180 seconds to investigate the alarm. If fire is not found, then the trained professional can reset the system. If the system is not reset, a second automatic fire detection device initiates, or any other fire alarm initiating device actuates, then the building will go into alarm and occupants will be notified in accordance with the building’s evacuation or relocation plan. Per NFPA 101, this type of alarm sequence is allowed with occupancy permission. An example of an occupancy that allows its use is new and existing educational occupancies. Summary It is essential to effectively notify occupants and responding personnel during emergencies. NFPA 72 and NFPA 101 fire alarm systems allow for both public and private mode notification to accomplish this, with options for presignal, positive alarm sequencing, and selective notification. Understanding the unique situation of a particular building will allow you to accomplish this most effectively. 
A building

Fire Sprinkler Considerations for Podium Construction

Podium, or pedestal, construction is a popular construction method that typically includes multiple stories of light wood framing over a single- or multiple-story podium of another, more fire-resistant, construction style which will often include retail or commercial space as well as parking levels. Often this is seen as Type V construction over Type I construction. This approach is used across the country and is most often utilized where the upper stories are residential occupancies. While there are certainly a number of fire protection and life safety issues to be addressed in these building types, for the purpose of this discussion we’ll focus specifically on the application of sprinkler protection for this construction type and particularly around where the use of NFPA 13R, Standard for the Installation of Sprinkler Systems in Low-Rise Residential Occupancies, is permitted in lieu of NFPA 13, Standard for the Installation of Sprinkler Systems.  What’s the difference between NFPA 13 and 13R? Assuming sprinkler protection is required; which for most buildings constructed in this manner building size, height, and occupancy will typically require it; a key decision point is determining if NFPA 13 is needed or if NFPA 13R can be used. The primary philosophical difference between the two is that NFPA 13 has a dual purpose of property protection and life safety while NFPA 13R has the purpose of providing life safety. The video below explains some of this difference.     While the difference might seem subtle there can be a great deal of savings based on the allowances of NFPA 13R. A major perceived benefit in using 13R can be the omission of sprinklers in areas that NFPA 13 requires sprinklers including small closets, concealed spaces, and attic spaces. These attic sprinklers are where a lot of complexity can come in since they will often require a dry system, or at least some other form of freeze protection, resulting in increased up-front costs and more long-term testing and maintenance considerations. NFPA 13R systems can also result in decreased water demands and therefore result in smaller pipe diameters. A very good analysis of the differences between NFPA 13, NFPA 13R, and NFPA 13D, Standard for the Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes can be found here.  Where can NFPA 13R be used in podium construction? The podium portion of the building will need to be protected by an NFPA 13 sprinkler system. Where 3-hour separation is provided at the top of the podium as required by building codes, the upper residential portion can then be evaluated as whether it is within the scope of NFPA 13R. This includes residential occupancies that are up to and including 4 stories in height and located in buildings not exceeding 60 ft (18 m) in height above grade. If it falls within this criteria, then NFPA 13R can be utilized for the protection. While the maximum building height above grade is fixed based on the definition of height above grade, the stories themselves can be counted from the 3-hour horizontal separation. The figure below demonstrates the differences in this criteria. It is important to note that the 2021 edition of the International Building Code limits the allowance of NFPA 13R where the limitation is four stories above grade plane. This is a significant change that impacts the application of the standard. A more in-depth analysis on this can be found here.  Still a design decision Even if 13R is permitted, nothing would prohibit the use of NFPA 13 to provide added property protection required by that standard. In fact, there are building code trade-offs that can only be used with NFPA 13 systems; and the ability to take advantage of those is not available when NFPA 13R is used. Even where that is not the case, there are cost benefits but it is important to understand the goals of NFPA 13R. While a fire in a living space should be controlled as it would be with a NFPA 13 system, a fire originating in a concealed space or in an unsprinklered attic can result in the loss of the building. If all occupants are able to safely evacuate, the system has done its job even if the building is a complete loss, whereas an NFPA 13 system should be able to protect the occupants and provide property protection.
Warehouse

Seeking input on ignition sources in warehouses for Fire Protection Research Foundation project

Oxygen reduction (or hypoxic) systems (ORS) are being used in warehouse facilities as an alternative to sprinkler protection. The basic principle of operation is to displace the ambient oxygen in an enclosed environment with one or more nitrogen generators.  Recently, the Fire Protection Research Foundation completed a project to review literature on the topic and identify research needs.  The research revealed that the test methods may not be sufficient for real-scale scenarios and may result in oxygen concentrations too high to prevent ignition. More research is needed on ORS test methods with a specific focus on: Data on real-world scenarios with the systems including information on reliability and maintenance issues Full- or real-scale validation of test methods that considers multiple types of ignition sources such as radiative and electrical high energy arc Data on ignition potential based on material type and storage arrangement for different O2 concentrations. Further research on the required oxygen concentration for specific fuels and applications. Therefore, the Foundation is conducting a second phase of "Review of Oxygen Reduction Systems for Warehouse Storage Applications" to develop both a prescriptive and performance-based design approach to select design oxygen concentrations for oxygen reduction system installations in warehouse applications. To do so, the project team is investigating ignition sources present in warehouses in order to evaluate and propose test methods for determining required oxygen levels for fire prevention purposes. As part of that effort, we have a questionnaire about ignition sources in warehouses to gather input from experts and stakeholders in the field. If you have any incident insights that you can share, please fill in the survey here. Information is collected anonymously unless you opt to provide contact information. Thank you in advance for your participation! 
Live sprinkler

The biggest problem with fire sprinklers? Not enough places have them.

The recently published 2021 edition of the NFPA US Experience with Sprinklers report shows that properties with sprinklers have lower rates of fire deaths and injuries. In most occupancies, property loss is also reduced. From 2015 to 2019, local fire departments responded to an estimated average of 51,000 structure fires per year (10 percent) in which sprinklers were present. Sprinklers are in all kinds of buildings, ranging from homes to hospitals, schools to stores, etc.  Compared to reported fires in properties with no automatic extinguishing systems (AES) such as sprinklers, range hood extinguishing systems, etc., when sprinklers were present, the civilian fire death and injury rates per fire were 89 percent and 27 percent lower, respectively. The rate of firefighter injuries per fire was 60 percent lower. Sprinklers are highly reliable and effective in suppressing fires and reducing loss. Sprinklers operated in 92 percent of such fires and were effective at controlling the fire in 96 percent of the incidents in which they operated. Overall, sprinkler systems operated and were effective in 88 percent of the fires considered large enough to activate them. One sprinkler is usually enough to control a fire. In 77 percent of the structure fires where sprinklers operated, only one operated. In 97 percent, five or fewer operated. Fire spread was confined to the object or room of origin in 95 percent of reported structure fires in which sprinkler systems were present compared to 71 percent in properties with no AES. Home fire sprinklers The report also includes a section specifically on sprinklers in home fires. Despite the fact that more people die from home fires than fires in any other occupancy, sprinklers were present in only 7 percent of reported home fires.  Compared to fires with no AES, in home fires with sprinklers present, rates per reported fire were: 88 percent lower for civilian deaths, 28 percent lower for civilian injuries, and 78 percent lower for firefighter injuries The average loss per fire was 62 percent lower for home fires with sprinklers compared to fires in properties with no AES. Sprinklers operated in 95 percent of the home fires in which the systems were present and the fires were considered large enough to activate them. They were effective at controlling the fire in 97 percent of the fires in which they operated. Taken together, sprinklers operated effectively in 92 percent of the fires large enough to trigger them. Learn more about home fire sprinklers from the NFPA Fire Sprinkler Initiative. Check out the full report for more information about sprinklers in all occupancies.
Firefighters watching virtual reality

Fire Sprinkler Side-by-Side Burn Brings Reality Closer to Home with New Virtual Reality Video

I did not truly understand just how effective fire sprinklers were until I saw the Home Fire Sprinkler Coalition’s (HFSC) virtual reality live fire video demonstration. I have interned at NFPA for a few months, so I knew going in that fire sprinklers are key for fire safety. However, this video showed me that fire sprinklers are so much more effective than I originally thought and have the power to save one’s belongings, home, and even life. They should be installed in every home. The other week in Ashland City, Tennessee, the National Fire Sprinkler Association (NFSA) and HFSC teamed up to record a live fire video shoot at a single-family home. The video they made was produced for virtual reality, allowing the user to get a 360-degree view during the video so they can see every angle of the house and what is happening. In the past, fire departments have conducted side-by-side live burns to demonstrate the power of fire sprinklers. However, doing a live burn demonstration is not always practical. They would require at a minimum construction of the units and EPA burn approval. Having access to virtual reality technology brings fire sprinkler education to a whole new level that is not only more personal, powerful and memorable, but eliminates the added layer of physical set up, rehab and travel. The demonstration takes place in two identical rooms. One room has a fire sprinkler and the other doesn’t. Both fires were started on the window curtain. The video starts with the room with the fire sprinkler. The impact of the sprinkler is almost immediate. The sprinkler, activated by the heat of the fire, goes off after about 30 seconds. At this point, the fire has engulfed one side of the window curtain. When the sprinkler activates, the fire is put out entirely. Once the fire is put out, I could see that the damage from the fire is limited to a small corner of the room. While the room is soaked, the video notes that a family would be able to move back into the room within a couple of days. The video then switches to the room without the fire sprinkler. The fire again quickly engulfs the window curtain. However, with no fire sprinkler, there is nothing to slow the fire down. After one minute, the fire is raging. After 90 seconds, one side of the room is completely engulfed in flames. Flashover takes place just over two minutes. The room becomes completely black with smoke and so hot that one of the cameras stopped operating. The sheer speed that flashover took place was eye- opening. The video shows the aftermath of the room. It is completely destroyed. Everything is black. It is completely unhabitable. After watching the video, it is easy to see how fire sprinklers can save lives. This live fire video shoot further demonstrates the need for every home to have a fire sprinkler system installed. According to NFPA's "U.S. Experience with Sprinklers" report the civilian death rate was 81 percent lower in homes with fire sprinklers than in homes without them. the average firefighter injury rate was nearly 80 percent lower when fire sprinklers were present during fires. when sprinklers were present, fires were kept to the room of origin 97 percent of the time. the home fire death rate was 90 percent lower when fire sprinklers and hardwired smoke alarms were present. By comparison, this death rate is only 18 percent lower when battery-powered smoke alarms are present but automatic extinguishing systems weren't. The virtual reality video is scheduled to be completed later this year and will allow people to experience firsthand a fire with and without fire sprinklers, right in their own living room. A 2D version of the video will also be created for free, on-demand access via Internet. Watching the video will change your outlook on home fire sprinklers; I know it changed mine. Learn more about HFSC’s virtual reality education kit through this short video. Photos with captions are also available.

Standpipe System Design and Calculations

Standpipe systems consist of piping and hose connections installed throughout a building to provide reliable water for the manual suppression of a fire by either the fire department or trained personnel. NFPA 14, Standard for the Installation of Standpipe and Hose Systems, Chapter 6, outlines design and installation requirements for standpipe and hose systems. Standpipe systems can be broken down into different types of systems to delineate whether the piping is full of water (wet) or not (dry) and whether the water supplied for firefighting is automatically provided by a water supply, such as a city main or a tank and fire pump (automatic or semi-automatic), or needs to be provided by a fire department pumper (manual). When designing a system, you first need to determine the supply pipe size, hose connection location, size, and pressure based on the standpipe classification. There are three classes of standpipe systems, they include Class I, Class II, and Class II. Class I Class I systems are installed for use by the fire department and are typically required in buildings that have more than three stories above or below grade because of the time and difficulty involved in laying hose from fire apparatus directly to remote floors. Class I systems are also sometimes required in malls, because these occupancies contain areas that are difficult to access directly with hose from fire apparatus. Locations for hose connections in Class I systems include: Each main floor landing or intermediate landing of required stairs. On the roof if the stairwell does not have access to the roof. Each side of exit openings in horizontal exits. Exit passageways. Additional hose connections should be available in unsprinklered buildings where the distance from a hose connection to the most remote part of the floor exceeds the limits in NFPA 14 based on the sprinkler system type and building type. The minimum residual pressure required for a Class I system is 100 psi (6.9 bar) from the hydraulically most  remote 2 ½ in. (65 mm) hose connection with a flow rate of 500 gpm (1893 L/min), through the two most remote 2 ½  in. (65 mm) hose connections. A pressure-regulating device may need to be used in order to limit the pressure at hose connections to less 175 psi (12.1 bar) static (pressure when not flowing).            Class II Class II are installed for use by trained personnel and are often required in large un-sprinklered buildings. They might also be required to protect special hazard areas, such as exhibit halls and stages. In the past, Class II standpipes were typically installed with a hose, nozzle, and hose rack on each hose connection. Prior to the 2007 edition of NFPA 14, Class II systems were defined as being for use “primarily by the building occupants or by the fire department.” Because of concerns regarding the ability of untrained occupants to safely use the hose and the encouragement of occupants to fight the fire rather than evacuate, the Technical Committee chose to define Class II systems as being for use by “trained personnel or by the fire department.” Class II systems need to provide enough hose stations so that all portions of each floor level of the building are within 130 ft (39.7 m) of a 1 ½ in. (40 mm) hose connection provided with 1 1∕ 2 in. (40 mm) hose or within 120 ft (36.6 m) of a hose connection provided with less than 1 1½ ∕ 2 in. (40 mm) hose connection. The minimum residual pressure required for a Class II system is 65 psi (4.5 bar) from a remote 1 -1/2½ in. (40 mm) hose connection with a minimum flow rate of 100 gpm (379 L/min). A pressure-regulating device may need to be used in order to limit the pressure at these hose connections to less than 100 psi (6.9 bar) residual (pressure when flowing) and 175 psi (12.1 bar) static (pressure when not flowing). Class III Class III systems combine the features of Class I and Class II systems. They are provided for both full-scale and first-aid firefighting. These systems are generally intended for use by fire departments and fire brigades. Because of their multiple uses, Class III systems are provided with both Class I and Class II hose connections and must meet the placement, pressure, and flow requirements for both Class I and Class II systems. Pipe sizing The minimum size pipe for Class I and III standpipes is 4 in. (100 mm). If the standpipe is part of a combined sprinkler system in a partially sprinklered building, that is increased to 6 inches (150 mm). If the building is protected with an automatic sprinkler system, then the minimum combined standpipe size can be 4 in. (100 mm) if hydraulically calculated. The branch lines of the standpipe system are to be sized hydraulically but cannot be smaller than 2 -1/2½ in. (65 mm). Calculating Hydraulically calculating a standpipe system is very similar to that of a sprinkler system because we are calculating the pressure lost in the system to get the required flow to the most remote hose connection. In addition to the required flow from the most remote hose connections, based on the classification we are required to also calculate flow from connections on each standpipe. For example, when calculating a Class 1 Standpipe system in a building that is less than 80,000 ft2 (7432m2) we need to calculate the flow rate of 500 gpm (1893 L/min), through the two most remote 2 ½  in. (65 mm) hose connections at 100 psi (6.9 bar) and also calculate an additional 250 gpm (946 lpm) flowing from each standpipe in the building up to a maximum total flowrate of 1000 gpm (3785 L/⁠min) for buildings that sprinklered throughout, and 1250 gpm (4731 L/min) for buildings that are not sprinklered throughout. Take a look at this video taken from our soon to be released Online Certified Water-Based System Professional Learning Path discussing how to hydraulically calculate a standpipe system. Want to Learn More? Keep an eye out for our Certified Water-Based Systems Professional Learning Path. Also, If you found this article helpful, subscribe to the NFPA Network Newsletter for monthly, personalized content related to the world of fire, electrical, and building & life safety.
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