Topic: Fire Protection Systems

Fire Fighter Safety Building Marking Systems

There are two main ways in which fire fighters currently receive information about fire protection features and construction types of a building they are responding to. The first is from a pre-incident plan (see NFPA 1620 for information about pre-incident planning) which is available as a result of prior building inspection and the second is through signage on the building. The most widely adopted signage which most fire fighters are familiar with is the NFPA 704 hazard diamond, which provides information about hazardous materials present and the fire, health, instability and special hazards which they pose. However, there is a lesser-known marking system that has been developed and incorporated in Appendix C of NFPA 1, which if utilized can provide fire fighters the basic information about fire protection features and building construction quickly and concisely as they’re arriving on scene of an emergency. Let’s look at why this type of marking system is important to fire fighters. Modern buildings are designed with fire protection features to protect both occupants and the building itself. Some of these features provide active protection, such as fire suppression systems, while others provide passive protection such as fire resistive construction. The required protection level is dictated by the codes incorporated by reference into law by the authority having jurisdiction at the time the building was designed and constructed, or under a retroactive requirement after the building is occupied. The specific fire protection features in a building, combined with the construction type will play a role in the tactical approaches to suppressing a fire in that building. So, having this information quickly and concisely displayed on the exterior of the building can enhance the fire department’s effectiveness. Although some states have adopted signs identifying construction type and location of truss construction, the fire fighter safety building marking system (FSBMS) in Appendix C of NFPA 1 goes further to include the hazard level of the contents, presence of fire sprinkler and standpipe systems, occupancy and life safety issues and other special designations. What does it look like?   The Maltese cross, which draws its origins from the Knights of Malta, has been widely adopted as a symbol of the fire service. The eight-pointed cross can be easily identified by its curved arcs between the points which all converge on a center circle. The FSBMS utilizes a rating system in each of the arms of the cross and the center circle to concisely display the hazard level, fire suppression systems, occupancy life safety issues and special hazards of a given building. The image above is an example of a FSBMS symbol. These signs should be located “in a position to be plainly legible and visible from the street or road fronting the property or as approved by the fire department.” To aide in visibility the signs should incorporate a white reflective background and black lettering.  Now let’s look at what each of the letters in the four sections of the cross identify. Rating System Construction Type The construction type is identified utilizing letter combinations in the top section of the Maltese cross as follows: FR — Fire-resistive construction NC — Noncombustible construction ORD — Ordinary construction HT — Heavy timber construction C — Combustible construction These construction types provide firefighters a general understanding of how well the building will resist collapse under fire conditions. Fire resistive construction would theoretically resist collapse the longest and combustible construction has the potential for the earliest collapse. Hazards of Contents The hazard of the building’s contents as it relates to fire conditions will be displayed on the left section of the Maltese cross as follows: L — Low hazard. Low hazard contents shall be classified as those of such low combustibility that no self-propagating fire therein can occur. M — Moderate hazard. Moderate hazard contents shall be classified as those that are likely to burn with moderate rapidity or to give off a considerable volume of smoke. H — High hazard. High hazard contents shall be classified as those that are likely to burn with extreme rapidity or from which explosions are likely. The hazard level will provide fire fighters with a general idea of how rapidly a fire will grow and spread through the building contents. This information can be used to anticipate the amount of water and firefighting resources needed to effectively control the fire. Automatic Fire Sprinkler and Standpipe System The presence of automatic fire sprinklers and standpipe systems will be displayed in the right section of the cross as follows: A — Automatic fire sprinkler system installed throughout P — Partial automatic fire sprinkler system or other suppression system installed S — Standpipe system installed N — None The general understanding of what active fire suppression systems are located in the building will guide firefighter’s tactics including apparatus positioning and hose line selection. Occupancy/Life Safety Issues The occupancy and life safety issues will be displayed in the lower section of the cross as follows: L — Business, industrial, mercantile, residential, and storage occupancies M — Ambulatory health care, assembly, educational, and day care occupancies H — Detention and correction facilities, health care, and board and care occupancies This information about building occupants/occupancy type will allow firefighters to gauge the difficulty in evacuating occupants from the building. The L occupancies representing those where the occupant load is lower, and occupants can most effectively evacuate unassisted. The M is of moderate concern where the occupant load is higher and/or the occupants may need additional assistance due to age or health conditions. The H is of high concern where the occupants may not be able to self-evacuate and considerable resources will be needed to evacuate the building. Special Hazards The center circle has been left empty to allow the inclusion of special hazards or provisions. This may be a location to include such things as truss type construction or even the hazardous materials information for example an NFPA 704 diamond, as long as the provisions for size of 704 are met. Summary Having the information on construction type, hazard level of contents, presence of sprinkler and standpipe systems and occupancy/life safety issues has the potential to enhance the effectiveness of firefighters arriving on scene. These responders would be equipped with the knowledge needed to best address an emergency in the building. States which have incorporated NFPA 1 into law should take the extra step to specifically name Annex C in the incorporating ordinance, thus incorporating a national standard the firefighter safety building marking system into law in their jurisdictions. Unless specifically incorporated by refence the FSBMS in Annex C would be a recommendation rather than a requirement. A national system has the potential to increase firefighter effectiveness while decreasing the number of fire fighter injuries and deaths by providing important information quickly and concisely as they arrive on scene. 

Fire Protection Research Foundation publishes “Firefighting Foams: Fire Service Roadmap” report

Fire incidents involving flammable liquids have historically resulted in dire consequences. Incidents can occur in aircraft hangars, shipboard spaces, flammable liquids fueling facilities, large fuel storage tanks, and other settings and can range from small, short spill fires to large tank farm fires which can burn for multiple days. A prominent example of the latter is the Intercontinental Terminals Company Deer Park petrochemical facility fire in Texas in March 2019. That fire started on March 17 and was finally brought under control on March 23. Class B firefighting foams are the primary agents used for the vapor suppression and extinguishment of flammable liquid fires in both manual and fixed system applications. Firefighting foams form a film and/or a blanket of bubbles on the surface of flammable liquids and prevent the fuel vapors and oxygen from interacting and creating a flammable mixture. For nearly five decades, Aqueous Film Forming Foams (AFFF) have been used as the dominant and effective Class B firefighting foam. Prior to the adoption of AFFF, the primary agent for flammable liquid firefighting was Protein Foams, which are derived from the hydrolysis of protein products and then delivered as aspirated foam to produce a smothering blanket of foam bubbles on the fuel surface. AFFF contains fluorosurfactants (per- and poly- fluoroalkyl substances [PFAS]) that provide the essential characteristics of fuel repellency, heat stability, low surface tension, and positive spreading coefficient so that an aqueous film formation can be formed on the fuel surface. AFFF has traditionally been recognized for its effective fire control characteristics. However, today these foams are now of significant concern in light of potential adverse health and environmental impact. The potential environmental, safety and occupational health risks associated with the use of fluorosurfactants such as some PFAS present in AFFFs started to become evident to the scientific community in the early 2000s. The unique chemical nature of the carbon-fluorine bond in PFAS make some of these compounds persistent, bio accumulative, toxic and have emerged as “contaminants of concern” as considered by the EPA. As a result, the ability to use AFFF to extinguish Class B fires continues to be greatly restricted due to bans in numerous States in the United States and in countries across the world such as Australia. Recently, Federal and State authorities have implemented health and environmental regulatory actions for PFAS and PFAS-containing AFFF. These regulations will ultimately impact, if not eliminate the production, distribution, and use of legacy AFFF in upcoming years. As more regulations come into place to address this issue, fire departments and other industrial end users are seeking AFFF replacements. In the meantime, the capabilities and limitations of the replacement foams and agents are continuing to be investigated through various research and testing programs to better understand their characteristics and effectiveness for various applications. The Fire Protection Research Foundation (FPRF), the research affiliate of NFPA, facilitated a research testing program (2018-20) to evaluate the fire protection performance and effectiveness of multiple fluorine free Class B firefighting foams on fires involving hydrocarbon and alcohol fuels. This study provided guidance to inform the foam system application standard, i.e., NFPA 11, Standard for Low−, Medium−, and High− Expansion Foam based on the testing conducted at the time of this research, and identified knowledge gaps and research needs so that we can better understand the capabilities and limitations of fluorine free foams. Additionally, there are multiple other ongoing research efforts. There are research programs led by the US Department of Defense’s SERDP and ESTCP underway, including  testing on the development of PFAS-free firefighting formulations, studying the fire suppression performance and ecotoxicology of these formulations as well as the cleaning technologies for firefighting equipment. LASTFIRE (Large Atmospheric Storage Tank Fires), an international industrial end user consortium, has also been focusing on the selection and use of firefighting foams for large storage tank applications. Additionally, the Firefighter Cancer Cohort Study is developing a national framework to collect and integrate firefighter epidemiologic surveys, biomarkers, and exposure data focused on carcinogenic exposures and health effects. Part of the long-term cohort study will look at the health effects of firefighters that have been routinely exposed to firefighting foams during their activities and careers. Clearly, this is a complex problem, with concerns that include fire control/extinguishing performance, health exposure, and environmental contamination. And for the fire service, challenging Class B flammable liquid fires are not going away and must be addressed. The learning from these ongoing studies have been promising and demonstrate a step in the right direction to develop a full understanding of this complex problem so that we can transition to firefighting foams of the future without experiencing “substitution regret” (i.e., to avoid multiple repeated replacements over time). The Fire Protection Research Foundation recently published the report titled “Firefighting Foams: Fire Service Roadmap.” This project was initiated with the funding support from FEMA Assistance to Firefighters Grant (AFG) program, with an overall goal to provide guidance to the fire service community by developing a roadmap to transition from AFFFs to a suitable, environmentally friendly, non-toxic, and effective alternative. The roadmap document is based on the information available at the time of the program. The roadmap and associated documentation have been assembled in a systematic path that covers current regulations, considerations for transitioning to replacement foam, cleaning of equipment and disposal of effluents and legacy concentrates, foam selection and implementation considerations, minimizing firefighter exposures, and ways to handle foam discharged from a cleanup and documentation perspective. A key element of this project entailed a three-day virtual workshop hosted by the FPRF late last year, October 2021. Subject matter experts delivered 28 presentations on the state of knowledge and related issues. If you missed this FPRF workshop, please visit the project website for workshop presentations, and final proceedings. Did you know the Research Foundation is celebrating its 40th year in existence in 2022? Learn more about this noteworthy milestone at www.nfpa.org/fprf40.

Water Mist Systems Overview

Water mist systems are fire suppression systems that use very small water droplets to extinguish or control fires. These droplets are effective at controlling fires while using less water and having smaller piping than a standard sprinkler system due to the increased cooling effects, oxygen displacement and pre-wetting that the droplet size and distribution provide. Some additional benefits of water mist fire protection systems include reduced water damage and low environmental impact, while one of the trade offs include higher system pressure. This blog will review some of the basics about these systems to help add these systems as an option in your fire protection design portfolio. The droplet size for water mist systems can vary between 1000 microns and 10 microns. This small droplet size decreases the required application rate, enhances evaporation, and helps reduce oxygen levels to extinguish visible and hidden fires. Water mist systems have been used for specific applications (such as maritime) for a long time but starting in the mid-1990’s advancement in the use of water mist systems was propelled by the phasing out of halon and their use as a fire safety system for spaces where the amount of water that can be stored or discharged is limited. In addition, there is a long list of applications in which water mist systems have been listed for use including the following: Machinery spaces Combustion turbines Industrial oil cookers Computer room raised floors Data processing equipment rooms Chemical fume hoods Continuous wood board presses Shipboard passenger cabins and corridors Shipboard accommodation and public space areas Road tunnels Cable conduit tunnels Application There are a few different ways to apply water mist fire protection systems in your building or facility. These types of system configurations will look similar to clean agent system applications because the two systems share several commonalities in how they protect against fires. Local Application – This configuration is used to protect a specific hazard or object. An example may be the protection of a piece of equipment in a large compartment. The system would be designed to discharge water mist directly onto the object. Total Compartment Application - This type of system provides protection to all fire hazards and all areas in a compartment. The open nozzles are positioned in a grid so that water mist discharges approximately uniformly throughout the entire volume. Zoned Application - This type of system is configured to discharge mist from portions of a larger system as required to control fire in a specific part of a compartment. It would be installed in circumstances where the water demand for a total compartment system (i.e., a deluge system), would be beyond the capability of the water supply. Zoning the water mist piping network, however, requires the installation of a detection system that can accurately find the location of a fire. Occupancy Protection Systems - A water mist system utilizing automatic water mist nozzles installed throughout a building or a portion of a building and intended to control, suppress, or extinguish a fire. Nozzle types There are several different types of nozzles that can be found in a water mist fire protection system. Automatic - Nozzles that operate independently of other nozzles by means of a detection/activation device built into the nozzle. This activation device is typically a heat responsive element or actuator. Nonautomatic - Nozzles that do not have individual actuators or heat-responsive elements. These types of nozzles are used in deluge systems where the nozzles are always open. Multifunctional - Nozzles capable of operation using both automatic and nonautomatic means. The actuation of a multifunctional water mist nozzle can be by a built-in detection and activation device and/or by an independent means of activation. Electronically-operated automatic - Nozzles that are normally closed and operated by electrical energy that is initiated and supplied by fire detection and control equipment. System types There are various types of water mist systems which are the same categories as the different types of sprinkler systems. Since we recently posted a blog covering the types of sprinkler systems that goes into the details about each type, I’m going to keep this section brief and just give a quick overview. Deluge System - A water mist system utilizing nonautomatic mist nozzles (open) attached to a piping network connected to the fluid supply(ies) directly or through a valve controlled by an independent detection system installed in the same area as the mist nozzles. Wet Pipe System - A water mist system using automatic nozzles attached to a piping system containing water and connected to a water supply so that water discharges immediately from nozzles operated by the heat from a fire. Pre-action Systems - A water mist system using automatic nozzles attached to a piping system that contains air that might or might not be under pressure, with a supplemental detection system installed in the same areas as the mist nozzles. The actuation of the detection system opens a valve that allows water to flow into the piping system and discharges through all opened nozzles in the system. Dry Pipe Systems - A water mist system using automatic nozzles attached to a piping system containing air, nitrogen, or inert gas under pressure, the release of which (as from an opening of an automatic nozzle) allows the water pressure to open a dry pipe valve. The water then flows into the piping system and out through any open nozzles. Droplet production methods Water mist fire protection systems have the option of being either a single fluid (water) or twin fluid (water & atomizing media) system. Single-Fluid - A single-fluid media system requires one set of distribution piping to transport the fluid to each nozzle. The droplets are then formed in one of the following ways: Liquid should be discharged at a high velocity with respect to the surrounding air. The difference in velocities between the liquid and surrounding air should shear the liquid into small droplets. A liquid stream is impinged upon a fixed surface. The impact of the liquid on the surface breaks the liquid stream into small droplets. Two liquid streams of similar composition collide with one another. The collision of the two streams breaks the individual streams into small droplets. Liquid is either vibrated or electrically broken into small droplets (ultrasonic and electrostatic atomizers). Liquid is heated above its boiling point in a pressure vessel and released suddenly to atmospheric pressure (flashing liquid sprays). Twin Fluid – Twin-fluid media systems produce water mist (droplet production) by impingement of two fluids delivered from separate piping systems. One set of piping provides a liquid (water) to the nozzle, and the second piping network provides an atomizing fluid/media. Both single-fluid and twin-fluid systems can be operated in the low, intermediate, or high pressure range, which is based on the greatest pressure that the distribution piping is exposed to, as shown in the table below.     Low Pressure System Intermediate Pressure System High Pressure System Imperial Units Under 175 psi 175 – 500 psi Over 500 psi Metric Units Under 12.1 bar 12.1 – 34.5 bar Over 34.5 bar Conclusion Ultimately, while water mist fire protection systems have not yet outpaced the prevalence of traditional sprinkler systems there are numerous benefits associated with them to justify their use in many applications. For information on the requirements associated with water mist systems please see NFPA 750, Standard on Water Mist Fire Protection Systems and for more information on the systems themselves check out the NFPA Fire Protection Handbook, Chapter 16-8.

Impairment Procedures for Sprinkler Systems That are Out of Order

NFPA 25, Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems, provides the criteria for the routine activities that must be conducted to ensure that water-based fire protection systems can be relied upon in the event of a fire. These activities range from simple visual confirmation of some things such as valve position and room temperature on a more frequent basis, to much more complex activities such as full flow tests and internal assessments at longer intervals.  All of these activities are intended to keep sprinkler systems in working order. But what about when a system needs to be shutoff for repair or maintenance? What about when a water main is broken, a frozen pipe has burst, a fire pump has failed, or another major issue has been found during inspection or testing? At that point, the building contains a compromised sprinkler system and is no longer protected at the level that is expected while the system is in service. In NFPA 25, the term for a system that is out of order, is impairment, regardless of whether or not it was planned (see Deficiencies and Impairments of Sprinkler Systems). Impairments need to be addressed and resolved as quickly as possible in order to provide the expected level of protection for life and property. If the impairment is prolonged, additional measures need to be taken in consideration of life and property protection. Planning ahead Chapter 15 of NFPA 25 is dedicated to addressing the requirements that include the measures to be taken to ensure that increased risks are minimized, and the duration of the impairment is limited. A key provision here is that the property owner or designated representative must assign an impairment coordinator to comply with the requirements of the chapter (see Responsibilities of the Building Owner for Fire Sprinkler System Inspection Testing and Maintenance). The impairment coordinator should have a detailed plan, ahead of time for how they will handle both preplanned and emergency impairments and meet the requirements detailed below. Any preplanned impairments need to be authorized by this individual prior to removing the system from service. Tag Impairment System A tag must be used to indicate that a system, or part of the system, has been removed from service. The tag must be posted at each fire department connection and the system control valve, and other locations required by the authority having jurisdiction, indicating which system, or part, has been removed from service. Anyone who is shutting down a system should use tagging procedures even if the owner does not. Tags can also be itemized in a list to facilitate proper restoration of the system to working order. As tags are retrieved, they can also be used for verification that a valve or system has been restored to service. Impairment program While the system is out of service, NFPA 25 provides details on impairment programs and what they should cover: Determination of the extent and expected duration of the impairment Inspection of the area or buildings involved and determination of increased risks Submission of recommendations to mitigate any increased risks Notification of the fire department Notification of the insurance carrier, alarm company, property owner, and other authorities having jurisdiction Notification of supervisors in the areas affected Implementation of a tag impairment system Prolonged impairments In addition to these steps, what may be the most important or impactful provision is arranging for one or more of the following measures when the fire protection system is out of service for more than 10 hours in a 24-hour period: Evacuation of the building or portion of the building affected by the system out of service Implementation of an approved fire watch program Establishment of a temporary water supply Establishment and implementation of an approved program to eliminate potential ignition sources and limit the amount of fuel available to a fire Restoring systems to service When repair work has been completed and the system is restored to service, the following items need to be confirmed: Any necessary inspections and tests have been conducted Supervisors have been advised that protection is restored The fire department has been advised that protection is restored The insurance carrier, alarm company, property owner, and other authorities having jurisdiction are notified that protection is restored The impairment tag(s) are removed While we certainly hope that fire sprinkler systems can be maintained in continuous service there are times where planned service, maintenance activities or unexpected circumstances cause the system to be out of service. Assigning an impairment coordinator, planning ahead, and understanding Chapter 15 of NFPA 25 will help to minimize the risk posed while the system is impaired.

Fire Alarm Notification Delay from Sprinkler Waterflow

Over the past several months, I have noticed a few incidents occurring in mercantile occupancies that have raised some questions related to the allowable delay between sprinkler activation and fire alarm notification in the event of a fire, which is governed by NFPA 72®, National Fire Alarm and Signaling Code®. One example is a video of this fire in a Maryland Walmart. The video was taken by an occupant inside the building as they are exiting the building and shows sprinklers operating and controlling the fire. You notice that there is a time delay between the activation of the sprinklers and the activation of the occupant notification within the building. Many people are asking the question, why doesn’t the fire alarm immediately warn the occupants that there is a fire in the building as soon as the sprinklers activate? The answer is that NFPA 72 permits up to a 100-second delay between sprinkler waterflow and occupant notification, as you can see at the end of the video, the fire alarm did activate the occupant notification via audible and visual notification. The allowance for a 100-second delay before the actuation of alarm notification appliances is broken down into two requirements. The first requirement is related to the waterflow initiating device and found in section 17.13 of the 2022 edition of NFPA 72. 17.13.2 requires that the waterflow initiating device activate within 90 seconds after a flow occurs that is equal to or greater than the flow from a single sprinkler of the smallest orifice size. The 90-second allowance exists to reduce the number of nuisance alarms caused by water flow that can occur from pressure surges in the water supply system and allows time for the flow from a sprinkler in the system to be detected at the riser. The delay provides added assurance that the water flow in the sprinkler piping is in fact sustained flow from a sprinkler, and not just the result in a change in pressure. The reduction of nuisance alarms is important because a fire alarm system that has many nuisance alarms can cause the occupants to become complacent and may begin to ignore the fire alarm. This delay in the water flow switch activation can be created within the flow switch itself using a retard dial, or it can be accomplished with the use of a retarding device such as a retard chamber when using a pressure switch that is connected to the alarm port on a sprinkler system alarm valve. The second part of this delay is found within section 10.11.1. This section requires that the actuation of alarm notification appliances at the protected premises occurs within 10 seconds after the activation of the initiating device. This requirement exists to ensure that the operation of the notification appliances occurs within a timely manner after a fire has been detected. Between those two requirements in section 17.13.2 and 10.11.1, NFPA 72 permits up to a 100-second delay between the initial waterflow from a sprinkler and the actuation of the notification appliances within the building. In addition to this allowance intended to reduce the number of nuisance alarms, allowances exist to delay the actuation of notification appliances for other initiating devices with the use of a presignal feature or positive alarm sequence, though both require a detailed response plan and approval from the authority having jurisdiction. The next time someone asks you a question about the timing of sprinkler waterflow and fire alarm notification, remember that NFPA 72 permits the delay in the actuation of fire alarm notification appliances. This timing is engineered into the operation of the systems, and it exists to ensure that they function as effectively as possible and reduce unwanted nuisance alarms.

Fire Department Use of Sprinkler Systems

At the first NFPA meeting in 1896 the first consolidated set of sprinkler installation rules were established, becoming what is today known as NFPA 13, Standard for the Installation of Sprinkler Systems. Formalizing the sprinkler installation standards increased fire sprinkler effectiveness, however, a gap still existed in the use of fire sprinkler systems. In 1933 a brochure titled “Use of Automatic Sprinklers by Fire Departments” was published providing fire departments with guidelines on how to best capitalize on the effectiveness of fire sprinkler systems during incidents. This brochure evolved over the next 33 years into the Recommended Practice for Fire Department Operations in Properties Protected by Sprinkler and Standpipe Systems, NFPA 13E first published in 1966. Today NFPA 13E provides the information necessary to ensure fire departments are trained on and operate effectively with automatic fire sprinkler systems. Although some fire sprinkler systems are designed to suppress a fire, most are designed to control a fire. The main difference between fire control and fire suppression is related to the fire sprinkler systems impact on the fires heat release rate. The graph below depicts fire control (dotted line) versus fire suppression (solid line). Fire sprinklers controlling a fire result in a steady heat release rate, keeping the fire from growing, and fire sprinklers suppressing a fire will result in a decreasing heat release rate. The three principal causes of fire sprinkler system failures identified in NFPA 13E are a closed control valve, inadequate water supply for the system and occupancy changes that render the installed system unsuitable. Beyond the primary causes found in the recommended practice, NFPA has conducted research on the U.S. Experience with Fire Sprinklers to help understand fire sprinkler effectiveness. Let’s take a second to review the three main causes found in the recommended practice all of which responding fire department personnel can impact positively. Closed control valve Familiarization with the types of control valves and their layout in a system allows firefighters to both understand what valves will disrupt water flow and what position have they should be in for effective operation. Should they encounter a valve which is not in the correct position during a fire, placing that valve in the correct position may restore the system effectiveness. This is not a hard and fast rule however, since the fire may have already operated more sprinkler heads than the available water supply can support, making the system ineffective. Additionally, fire departments should never turn off a sprinkler system that has activated until they have confirmed the fire is fully extinguished and overhaul has taken place. Even if ventilation is needed to increase visibility and conduct search and rescue, the system should remain operational to control the fire as these tasks occur. Once this occurs, steps should be taken to identify if only a portion of the system needs to be shut down (a zone) rather than the entire system. Anytime the system is shut down a firefighter with a portable radio should remain at the control valve to immediately open the valve should the fire not be fully extinguished. Simply turning the system back on may not reestablish fire control. Fire sprinkler systems are designed to control a fire utilizing a specific number of sprinklers at a design pressure and flow. If the system is shut off prior to the fire being extinguished the potential exists for additional heads beyond the design to activate. When the system is turned back on the available water supply may not cover the operated heads leading to ineffective water application and a fire that is no longer controlled. Inadequate Water Supply The water supply may be inadequate due to a lack of available water flow, lack of available pressure or both. Since fire department pumpers often have the capacity to supply water at higher flow rates and pressures than the normal water supply, utilizing a fire department pumper to supply water to the fire department connection (FDC) can address most inadequate supply concerns. The FDC will often bypass many of the control and check valves in the system, supplying water directly to the operating sprinklers. NFPA 13E recommends a pressure of 150 psi (10 bar) to effectively suppl fire sprinkler systems, unless additional signage is provided to indicate a different pressure. The fire department can also have a negative impact on the water supply to a fire sprinkler system. Although fire sprinkler systems are designed with a hose stream allowance or amount of water the fire department may potentially need to fully extinguish the fire, this may not be sufficient. For more information on fire flow check out this blog Calculating the Required Fire Flow. The hose allowance accounts for water needed at the base of the fire, which if the fire department cannot effectively apply water to the base of the fire, more may be needed. Utilizing more water from the supply than accounted for has the potential to reduce the sprinkler system effectiveness, eliminating its ability to control the fire, resulting in fire growth and the need for more water. Supporting the system through the FDC ensures that even if more water is needed than the original allowance, the sprinkler system still has an available supply at an effective flow and pressure. Occupancy changes Although the fire department does not have an ability to impact occupancy changes during a fire incident, an effective preplan and inspection program has the potential to identify occupancy changes which can adversely impact fire sprinkler system effectiveness before fires occur. Training those conducting these inspections to understand what types of commodities would represent a high heat release rate fire and how to identify if a sprinkler system could be designed to deliver the necessary water density can reduce this potential cause of failure. Summary As with all NFPA recommended practices, the language is less rigid than a standard or code, utilizing “should” instead of “shall” as to not limit the individual fire departments, allowing them to adopt more effective procedures. Familiarization with NFPA 13E provides anyone who may be utilizing a fire sprinkler system the knowledge necessary to positively impact the systems effectiveness.  Check out NFPA 13E to help your department identify the recommended training and operations for those responding to emergencies involving activated fire sprinkler systems. Interested in learning more, check out the resources below for additional information on fire sprinkler systems and fire department access. Sprinkler system Basics: Types of Sprinkler Systems The Basics of Sprinkler Thermal Characteristics Types of Sprinklers NFPA 1: When is Fire Department Access Required?
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