AUTHOR: Brian O'Connor

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What is the Secret about Private Operating Mode?

Everyone is familiar with the sound of a fire alarm and flash of the visual notification thanks to drills that are required at schools and the workplace. They are typically designed in a way so that everyone can see and hear, no matter where you are located in the building. What happens when you are in a building such as a hospital or correctional facility where notification of everyone in the facility could cause panic, interrupt delicate surgeries or damage a newborns hearing or vision? Are buildings permitted to have an alarm that privately notifies only those who need to take action? If so, what alternate requirements must be followed? This blog takes a look at private operating mode alarm systems, and their requirements. What is it?   Private Operating Mode is an audible or visual signaling only to those persons directly concerned with the implementation and direction of emergency action initiation and procedure in the area protected by the fire alarm system. Provided that those persons receive alarm notification, audible and visible signaling is not required to other building occupants who are not responsible for the implementation and direction of emergency action. For instance, if this was implemented in a correctional facility, the officers would need to be notified since they would be the ones who implement emergency actions, which would be to evacuate the inmates.   Private operating mode differs from public operating mode in several ways. In general, private audible notification is permitted to have a lower volume than public mode. Both public and private audible notification allow the AHJ to reduce or eliminate the audible if visual signals are provided. Visual notification is required in all public spaces per the ADA when using public mode and NFPA 72 National Fire Alarm and Signaling Code gives you specific requirements for how bright they must be, for private visual notification it is just required to be of sufficient quantity and intensity to meet the intent of the system. When can I use it?   The main rule when looking at where you can use private operating mode comes from NFPA 101 Life Safety Code. It says that private operating mode is allowed in places where occupants are incapable of evacuating themselves because of age, physical or mental disabilities, or physical restraint. Certain places come to mind such as detention/correctional facilities, prisons, jails, hospitals, same day surgery centers and day care occupancies. Ultimately, this should be a discussion you have with your AHJ to determine if the facility in question meets the requirements to allow it to be protected with a private operating mode fire alarm system.   Healthcare Specific Requirements   NFPA 99 Health Care Facilities Code contains some specific requirements regarding the use of the private operating mode for healthcare facilities. It clearly allows the use of private operating mode but adds additional requirements. For example, the notification needs to identify the smoke zone or floor area, floor and building where the responsible staff need to respond. It also needs to be heard throughout the facility except where notification would adversely affect patient care (surgical rooms, patient sleeping rooms, psychiatric care areas, etc.) Notification can also be omitted in areas that would interfere with patient treatment or areas where occupants will be alerted by staff. This is often done by coded messages like “Dr. Blaze, Code Red fourth floor west wing,” so that everyone can hear the message but only those trained to recognize the message will respond. This is still a subject that needs to be better understood by fire alarm designers and AHJs alike. It requires an analysis of the situation and an understanding of human behavior. Private operating mode isn't a one-size-fit-all solution. It must be integrated into the facilities emergency response plan and the responsible personnel must be properly trained in order for the system to work correctly, but if done right it has the potential to save lives. Let me know if you have any experience with private operating mode installations or approvals in the comments below. Also look out for changes in the 2021 edition of NFPA 101 which further aligns with the requirements found in NFPA 72 and NFPA 99. 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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6 Facts about Sprinkler System Corrosion and Steps to Help Minimize its Effects

Corrosion is a costly problem for sprinkler systems. It can cause leakage which can lead to impaired sprinkler systems, water damage, and eventually replacement of the entire system. This blog looks at  what corrosion is, where we can find it, how it affects a sprinkler system, and how to spot and prevent it. What is corrosion? Generally, when we refer to corrosion we are talking about when a metal reacts with its environment which leads to deterioration of the metal. In sprinkler systems this is often when oxygen reacts with iron to form iron oxides, which we commonly refer to as "rust." This is further accelerated when it occurs in the presence of water, which helps the reaction. While this is the most common, there are other types of corrosion that can affect a sprinkler system such as microbiologically influenced corrosion (MIC) and galvanic corrosion.  For any metallic component of a sprinkler system there is both external and internal corrosion. While both of these issues can lead to system failure, internal corrosion is more difficult to detect and causes more issues. Internal corrosion usually begins to form at the air/water interface while external corrosion is more dependent on the environment. Where does corrosion occur? There are many locations where piping and sprinklers are more susceptible to external corrosion. Most of these locations have different elements in the atmosphere that can speed up corrosion. A few common examples include: Areas with fertilizer or manure (animal pens) Pools or areas containing pool chemicals Areas near the ocean that are exposed to outside salt air Salt storage Pipe is in contact with soil Areas with excessive moisture (steam room) Listed corrosion resistant sprinklers and corrosion resistant piping, fittings and hangars are required to be installed in places where corrosive conditions are known. Meanwhile all pipes and fittings installed on the exterior of the building are required to be corrosion resistant. Internal corrosion on the other hand occurs most commonly where metal, water and air are in contact with one another. This occurs in both wet and dry pipe systems. For wet pipe systems, corrosion occurs most often near the pockets of air that could be trapped in high points. For dry and preaction systems the corrosion occurs most often at the low points because that is where any residual water builds up. How does corrosion affect a sprinkler system? Corrosion has a detrimental effect on sprinkler systems, causing the components to fail. For piping this can take the form of pinhole leaks or having rust buildup limit the flow of water (see image below). For sprinklers, corrosion can clog the water discharge orifice, affect the deflector and discharge pattern, or completely seal the plug, preventing water from reaching the fire. Other components such as piping hangers and fittings can also be susceptible to corrosion, which can lead to further complications.  What can I do to minimize corrosion? Completely eliminating the possibility of corrosion is nearly impossible, however there are some steps that can be taken to help reduce the amount of corrosion in a system: Better pipe material: When trying to delay corrosion a great place to start is looking at the material used. Certain types of piping are more resistant to corrosion, such as plastic CPVC, copper or galvanized steel. There are also benefits to using thicker piping since rust will not eat through the wall of the pipe as quickly. Using higher quality material may cost more up front but it will extend the life of the system and increase reliability.  Corrosion resistant sprinkler: When sprinklers are installed in areas susceptible to external corrosion, they need to be corrosion resistant. This means that they need to be either made out of corrosion resistant material, covered with a special coating such as wax, or plated with a corrosion resistant metal (see image below). Water supply: NFPA 13, Sandard for the Installation of Sprinkler Systems, requires the water supply to be evaluated to determine if it contains any unusual corrosive properties or is likely to contain MIC. If it does, then you need to either install piping that is corrosion/MIC resistant, treat the water with water additives, implement a monitoring plan, or fill your system with nitrogen for dry or preaction systems. Wet Pipe: Air Venting: NFPA 13 requires a vent to be located at a high point in the system to allow air to be removed by either a manual or automatic valve. This can be a reasonable approach on wet pipe sprinkler systems to reduce corrosion activity. The purpose of the air venting valve is to exhaust as much trapped air as possible from a single location every time the system is filled, thus having less oxygen for the metal to react with.  Dry Pipe: Drain Water Out of System: Just like how in wet pipe systems you want to remove the air out of the piping, for dry pipe or preaction systems you want to remove the water. Dry pipe and preaction systems are required to be pitched to a low point drain so that water can be removed from the system. Since most corrosion occurs at the air/water interface this will help prevent corrosion. Dry Pipe: Nitrogen: For dry pipe or preaction systems nitrogen can be used to fill the sprinkler piping network instead of air. When a system is filled with nitrogen it  contains very little oxygen, which is a vital ingredient in the corrosion process. Nitrogen can be provided through cylinders or a nitrogen generator.     How can I spot corrosion? Some corrosion can be easily identified while others can be hidden. During your annual floor level inspection of piping, fittings and sprinklers be sure to keep an eye out for exterior corrosion which can be identified by its orange-brown color and rough texture.   Internal corrosion is more difficult to identify during your annual inspection so an assessment of the internal condition of piping is required to be conducted every five years. Outside of that assessment, the effects of both internal and external corrosion can be seen by looking for water stains or leaking pipe where corrosion could have created pinhole leaks in your system by eating through the wall of your piping (see image below).       What do I do if I see corrosion? When there is significant corrosion buildup that is detrimental to sprinkler system performance, that section of piping, or sprinkler needs to be replaced. If corrosion is bad enough sometimes an entire system needs to be replaced. Addressing these issues will help ensure the reliability of your sprinkler system, increase the life expectancy of your system and in the long run save you time, energy, and money. Share your experience working on a system that was installed in a corrosive atmosphere in the comments below. What was the biggest challenge or lesson learned? 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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Arizona ESS Explosion Investigation and Line of Duty Injury Reports Now Available

Two reports from the Surprise, Arizona Energy Storage System (ESS) explosion that occurred in April, 2019 were published this week.  One report, titled, “Four Firefighters Injured In Lithium-Ion Battery Energy Storage System Explosion – Arizona” is written by the UL Firefighter Safety Research Institute and is part of a Study of Firefighter Line of Duty Injuries and Near Misses. The other report, “McMicken Battery Energy Storage System Technical Analysis and Recommendations” by DNVGL, on behalf of Arizona Public Service, is an investigation report into the incident. The DNVGL report looks at how we can prevent this incident from happening again and the UL report analyzes first responder considerations with regards to the incident. Both documents are examples of how we can learn from past incidents to improve our codes and standards, increase the safety of our first responders, and build a safer environment. The Incident On April 19th, 2019 an explosion occurred at the McMicken Battery ESS in Surprise, Arizona injuring four firefighters. The battery ESS was placed into service in 2017, which is prior to the publication of NFPA 855. The system was comprised of 10,584 Lithium Nickel Manganese Cobalt (NMC) battery cells organized in modules and racks within an ESS specific walk-in enclosure. The system included a total flooding clean agent fire suppression system, a very early smoke detection apparatus, and an HVAC system. The entire system could supply 2MW over one hour (2MWh) and was used to supplement solar panels at the time of the incident. While there was some information about the incident already known, these reports provide a great level of detail, insight and recommended paths forward. Technical Analysis Report The DNVGL report documents a thorough investigation that was conducted on the incident. It gives a lot of relevant background on the technology, the layout, and associated hazards. After building a foundation of knowledge about how batteries fail, the report analyses the factors that contributed to the failure and how we can prevent this from happening in the future. Some of the major conclusions reached in the report are as follows:   The cause of the incident was most likely an internal failure in a single battery cell which was caused by a defect in the cell. The clean agent fire suppression system that was installed was not designed to prevent or stop thermal runaway. The absence of barriers allowed thermal runaway to propagate from cell to cell. Flammable off-gases concentrated to create a flammable atmosphere and did not have a means to ventilate. The emergency response plan did not address extinguishing, ventilation, or entry procedures. Some of these items are addressed by NFPA 855, Standard for the Installation of Stationary Energy Storage Systems while others are included in the section of the report, “ Shortcomings that should be addressed in NFPA 855.” NFPA codes and standards are living documents that are constantly looking for ways to improve and keep up with new technology. Recommended improvements are always welcome in the form of Public Inputs or Public Comments.  First Responder Report This UL report gives an overview of the fire department and the incident. When addressing the responding fire departments, the document talks about their training, experience, equipment, and personnel. Regarding the Arizona incident, the report covers the building construction, the energy storage system, and responder PPE, and it walks through the timeline as well as provides a detailed incident narrative. This report does a great job addressing some of the contributing factors that led to the incident and firefighter injuries. Some of those factors include: HAZMAT training curricula does not cover basic ESS hazards. There was no way to monitor the conditions of the ESS container from a safe location. The emergency response plan didn't address mitigating ESS hazards and the plan was not provided to the responding personnel before the incident. Deflagration venting and explosion prevention systems were not provided in the ESS unit. The issue of training first responders on the basics of ESS hazards can be addressed through an updated NFPA online training course, Energy Storage and Solar Systems Safety Online Training for Fire Service Personnel. It is encouraging to see that such a collaborative approach was taken in response to this incident to determine what happened and what could be done to prevent this type of equipment failure in the future. In the field of ESS, one of the major needs of the industry is better information like this or other publicly available test data to help guide our codes and standards. A number of related reports, articles, relevant standards, and other content can all be found on NFPA's ESS webpage www.nfpa.org/ESS. Let us know what your thoughts are on these reports or if you've had any recent experience with ESS installations by commenting below.
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Suspended or Floor Mounted Vertical Obstructions – NFPA 13

There are many different requirements for obstruction in NFPA 13 Standard for the Installation of Sprinkler Systems  based on the type of sprinkler being used as well as the distance, type, and size of the obstruction. This blog will address suspended or floor mounted vertical obstructions requirements from the 2019 edition of NFPA 13 since this is a topic NFPA has recently received several technical questions on. What are suspended or floor mounted vertical obstructions? An obstruction is something that affects the discharge pattern of one or more sprinklers. An example of what a discharge or distribution pattern looks like is provided below:   (This is from the 2019 edition of NFPA 13, Figure A.9.5.5.1)   NFPA 13 section 10.2.7.2.2 gives a few examples of things that could be considered suspended or floor mounted vertical obstructions which include privacy curtains, freestanding partitions, and room dividers.   The basic rule for these obstructions is simple. There are tables in NFPA 13 which contains horizontal distances and the required minimum vertical distance that the obstruction must be from the sprinkler deflector. There are also figures to help you understand how the table should be used. Below are the table and figures for standard spray upright/pendent and sidewall sprinklers but the same table and figures are located in the extended coverage and residential sprinkler chapters.                         (This is from the 2019 edition of NFPA 13 Table 10.2.7.2.2 and Figure 10.2.7.2.2)     (This is figure 10.3.6.2.2 from the 2019 edition of NFPA 13)   You will notice that the relationship between the horizontal and vertical distances forms an umbrella shape similar to Figure A.9.5.5.1 above. The intent of this is to make sure the obstruction doesn't block the development of the sprinkler pattern which occurs within the first 18 vertical inches (450 mm) of the sprinkler. What about non-light hazard occupancies? You'll notice that the requirements for suspended or floor mounted vertical obstructions only apply to light hazard occupancies. These requirements shouldn't be applied for anything except light hazard occupancies because the testing that was done to justify the addition of this code section only evaluated sprinkler performance in a light hazard environment. Well, what do you do when you are in something other than a light hazard occupancy? The answer is that you should follow the general obstruction rules of NFPA 13. For obstructions below 18 inches for standard pendent and upright spray sprinklers this means that as long as the obstruction is less than 4ft (1.2 m) wide that it is not considered an obstruction. For obstructions less than 18 inches (450 mm) below the sprinkler deflector there are additional diagrams and tables you need to follow because of the potential to disrupt the sprinkler pattern development. A common rule that is followed for obstructions within 18 inches of the sprinkler deflector is the “three times rule”. This requires sprinklers to be positioned away from obstructions a minimum or three times the maximum dimension of the obstruction. Are there any exceptions?   Have you ever noticed that in healthcare facilities the privacy curtains are mostly solid except for the top 22 inches (550 mm)? According to NFPA 13, those privacy curtains are not considered obstructions if they follow three rules:  Curtains need to be supported by fabric mesh on a ceiling track The openings in the mesh part of the curtain needs to be at least 70% of the area The mesh portion of the curtain needs to extend at least 22 inches (550 mm) from the ceiling Those rules allow heat from the fire and sprinkler water discharge to pass through the mesh portion of the curtain without having a major impact on the sprinkler discharge pattern development or sprinkler activation time. Once again this exception to the rule can only be applied to light hazard occupancies. With all of this being said, it is also important to understand how the building will look when it is finished by reviewing all of the architectural, structural, and MEP drawings. Changes in any one of those drawings can create an obstruction to your once properly designed sprinkler system. Let us know what your experience is with suspended or floor mounted vertical obstructions in the comments below. 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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