Topic: Fire Protection Systems

A Guide to Fire Alarm Basics – Initiation

A fire alarm system is a crucial part of the overall fire protection and life safety strategy of a building . A fire alarm system serves many functions and the differences between the functions can be a bit confusing, so I created a visual guide to fire alarm basics. The objective of this blog series is to discuss some of the major components and functions of a fire alarm system. For an overview of the entire system take a look at my Guide to Fire Alarm Basics Blog. This blog will take a deeper dive into the initiation portion of a fire alarm system. The main function of the initiation portion of a fire alarm system is to report the status of a protected space or the existence of a fire. The components include all devices and circuits that send a signal to a fire alarm control unit (FACU) such as heat detectors, smoke detectors, carbon monoxide detectors, water flow switches, manually actuated devices, and pressure switches. Depending on the system, the signal from an initiating device can create an alarm condition or a supervisory condition. Based on the type of detectors and FACU, the signals can be sent over an initiating device circuit (IDC) for conventional systems, or a signaling line circuit (SLC) for addressable systems. Conventional initiating devices are typically detectors that use a switch contact to short both sides of the initiating device circuit together. By doing so, the initiating device causes an increase in current flowing through the circuit, which the FACU interprets as an alarm signal. Once one device shorts the circuit, no other device on that circuit or “zone” can send a signal. Because of this, any device on the circuit or “zone” will put the entire zone into an alarm state. Zones are typically designed to enable someone to easily identify an area where the alarm is located, for example, in a school you may have a gymnasium zone circuit and an auditorium zone circuit that each contain multiple devices. Addressable devices are either initiating devices or control/notification appliances that are capable of communicating a unique identification number or address to a control unit via a signaling line circuit. This identification consists of a binary string of 1s and 0s that indicate the address or location of that device on the circuit. When the FACU polls an initiating device, the initiating device responds with its status (Normal, Alarm, ect.) and address. The device address allows for the location of the detector to be identified at the FACU. When one initiating device is activated on a signaling line circuit, the FACU is still able to poll the other devices unlike a conventional initiating device circuit. Additionally, some addressable initiating devices are able to also transmit to the FACU a range of values of smoke density, temperature variation, water level, water pressure changes, and other variables. And then the control unit software determines the set points for initiation of an alarm, supervisory, or trouble signal. These types of initiating device circuits are known as analog addressable as they are able to tell the FACU their address and their value.   Ionization smoke detectors utilize a small amount of radioactive material to ionize air molecules into positively and negatively charged molecules that create a small electric current. The introduction of smoke into that ionized air will reduce the amount of current and cause an alarm signal.   Photoelectric smoke detectors utilize a light source and a photosensitive cell. When smoke enters the chamber, light scatters and is picked up by the photosensitive cell, causing an alarm signal. A beam smoke detector is like a photoelectric detector, except it is designed to cover a large area. A transmitter and receiver or reflector are placed to create a light beam across a space, when the amount of light being received by the receiver or reflected to the transmitter falls below a certain percentage, an alarm signal is sent. A non-restorable fixed temperature heat detector utilizes solder that holds up a plunger. The solder melts at a specific temperature and causes the plunger to drop, which shorts the contacts and causes an alarm signal.   A restorable fixed temperature heat detector utilizes two metals that have different thermal expansion coefficients. At a specific temperature, these metals will bend and cause the plunger to short the contacts, which causes an alarm condition. When the metal cools it will bend back in the other direction and restore itself.     A rate-of-rise detector utilizes an air chamber and a diaphragm. When a fire causes the air in the chamber to expand faster than it can escape out the vent, the increased pressure forces the diaphragm to close the contacts and initiate an alarm signal. This rate-of-rise detector also contains a fixed temperature plunger that will operate if the temperature exceeds the determined temperature.     An analog addressable heat detector utilizes a thermistor element to constantly monitor the temperature. The response criteria, which can be a temperature above a specified level, or a specific rate of rise in the temperature, is programmed at the FACU.   There are many different types of carbon monoxide (CO) detectors. One example of a CO detector is a Colorimetric detector. Like a photoelectric smoke detector, this detector contains a light source and a photocell that are constantly measuring for light being reflected from a chemical detector. In the presence of carbon monoxide, the chemical detector will change to a black color and light will no longer be reflected to the photocell, which will result in an alarm signal.   Sometimes called manual fire boxes, pull stations, or call points, manually actuated initiating devices initiate an alarm signal when there is an input from a person, such as pulling a lever or pushing a button. These can require multiple actions to initiate such as lifting a cover or breaking glass prior to actuating the device.   Flow switches are installed inside the piping of a sprinkler system and have a vane that moves with the flow of water. When water begins to flow within the pipe, the vane operates a switch that initiates an alarm.     Pressure switches are installed on sprinkler systems to monitor for a change in water pressure. A signal will be sent to the FACU when there is an increase in water pressure, which means that water is flowing though the sprinkler alarm valve. Want to Learn More? Like I noted in the beginning of this blog, if you are interested in learning more about fire alarm basics, take a look at my Fire Alarm Basics Blog. I will be updating this series over the next few months to add a deeper dive into different portions of the fire alarm system. 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.
A row of homes

Help Spread the Word About the Life-Saving Benefits of Home Fire Sprinklers During Home Fire Sprinkler Week May 16 – 22, 2021

The Home Fire Sprinkler Coalition (HFSC) is celebrating its 25th anniversary this year! To commemorate this great milestone, HFSC is developing new innovative tools and materials to support community outreach. One example is the popular Home Fire Sprinkler Week campaign set to launch on May 16 – 22, 2021. A project of HFSC and the NFPA Fire Sprinkler Initiative, this week-long campaign is the perfect opportunity to get the tools you need to help further the life-saving educational message of home fire sprinklers. Building on the great success of last year’s event, Home Fire Sprinkler Week will again go digital in 2021. The campaign is designed to help you virtually share messages and resources every day of the week on both a website and social platform such as Facebook, Twitter, Instagram, and LinkedIn. If you’re a member of the fire service, take advantage of materials and more social media graphics to share during the week or at any time of the year. Additional assets you will be able to use during the Week include: A brand new HFSW digital campaign to reach younger homebuyers to help emphasize the need for home fire sprinklers in communities A new video to highlight the green benefits of installing home fire sprinklers With each day of the campaign, you will find a different theme and related content like videos and graphics with posts, to share. You can choose one message or share all messages on any given day. The daily themes are: Monday, May 17: Fire is Fast Tuesday, May 18: Fire Sprinklers Are Part of Fire-Safe Communities Wednesday, May 19: It’s Easy to Live with Home Fire Sprinklers Thursday, May 20: Fire Sprinklers are Smart and Green Friday, May 21: Protect What You Value Most As we ramp up to Home Fire Sprinkler Week, stay tuned to the HFSC website for more campaign information and resources. We look forward to you joining us on May 16!  
Katy, TX building under construction fire

NFPA Addresses Building Under Construction Fires with New Fire Prevention Program Manager Online Training and Webinar Panel on April 15

The National Fire Protection Association (NFPA) launched a new Fire Prevention Program Manager Online Training Series today to help the building industry understand and adopt the strategies defined in NFPA 241 Standard for Safeguarding Construction, Alteration, and Demolition Operation. The topic will also be discussed by a panel of industry experts during an Addressing Fire Safety Challenges During Construction webinar on April 15. Fire Prevention Program Manager Online Training Series In recent weeks, massive building under construction fires have occurred in Las Vegas, NV, Dallas, TX, and Everett, WA, underscoring NFPA research which shows an average of 3,840 fires in structures under construction and 2,580 fires in structures under major renovation per year. Building under construction fires cause an average of four civilian deaths, 49 civilian injuries, and $304 million in direct property damage annually, while fires in buildings undergoing major renovation cause an average of eight civilian deaths, 52 civilian injuries, and $104 million in direct property damage annually. “This new online learning, centered around NFPA 241, was developed in the spirit of the NFPA Fire & Life Safety Ecosystem, which emphasizes the importance of applying referenced standards, investing in safety, and a skilled workforce,” NFPA President and CEO Jim Pauley said.  Although NFPA 241 calls for a fire prevention program manager, credentials for the role are virtually non-existent in the market today. To help construction company leaders, building owners, job site supervisors, code officials, fire marshals, facility managers, and fire protection engineers have the skills needed to ensure the safety of buildings under construction, NFPA developed the new five-hour, five-part online learning series, assessment, and digital badge based on the anticipated job performance requirements (JPRs) for fire prevention program managers proposed for the next edition of NFPA 241. The training covers general fire protection awareness for all people on construction sites and the role of fire prevention program managers on a construction project with an emphasis on: Building safety and fire protection systems Hazard protection Inspections, permits and procedures The NFPA online training series is intended for fire prevention program managers who are new to the role and is designed to help learn how to actively manage a fire prevention program for a typical construction project.  Addressing Fire Safety Challenges During Construction Webinar The NFPA webinar scheduled for April 15 will feature a panel of industry experts discussing key considerations for construction site fire safety, including fire risks and the role of the fire prevention program manager, with time allotted for a robust Q&A session. Webinar panelists providing perspective on the topic include: Jim Begley, PE, FSFPE, CFM, TERPconsulting, principal Matthew Bourque, PE, WS Development, director of Fire Protection and Construction Operations Dick Davis, PE, FM Global, AVP, senior engineering technical specialist Nicholas Dawe, division chief/fire marshal, Cobb County (GA) Fire and Emergency Services
Green buildings

Research Foundation webinar on “Fire Safety Challenges of ‘Green’ Buildings and Attributes”

In 2012, the Fire Protection Research Foundation (FPRF) published a literature review related to fire safety challenges of ‘green’ (sustainable) building materials, systems (technologies) and features. The aim of that work was to: identify documented fire incidents in ‘green’ buildings define a specific set of elements in ‘green’ building design, including configuration and materials, which, without mitigating strategies, increase fire risk, decrease safety or decrease building performance in comparison with ‘traditional’ construction identify and summarize existing best practice case studies in which the risk introduced by specific ‘green’ building design elements has been explicitly addressed and compile research studies related to incorporating building safety, life safety and fire safety as an explicit element in ‘green’ building indices, identifying gaps and specific needed research areas. Since 2012, there have been several major fire events, which involved ‘green’ materials, systems, and features (collectively, ‘green’ attributes) in buildings. Green design features have been associated with photovoltaic panels and roof materials, lightweight timber frame buildings, and combustible insulation materials. This webinar will present highlights from a comprehensive information review of how the landscape of fire safety challenges associated with “green” attributes of buildings has developed since 2012. It is based on a global information search into the following: fire events involving “green” and/or sustainable building materials, systems, and features emerging “green” building materials, systems, and features and research, regulatory changes, engineering approaches, risk mitigation strategies, and firefighting tactics associated with fire challenges with “green” and/or sustainable building materials, systems, and features. While the research is comprehensive in scope, it is not exhaustive in detail, given the extent of advancement in these areas that has occurred since 2012. And, while significant advancements have been made, gaps remain, and strategies for proactively incorporating fire performance into the development of new “green” building materials, systems, and features (product development) are lacking; the tools to proactively assess the fire performance of “green” building materials, systems, and features at the product level (e.g., fire performance testing), and as installed in buildings, are lacking; and a broader building regulatory framework and design philosophy for achieving sustainable and fire resilient (SAFR) buildings are also lacking. The final report from the most recent research effort is available here. Register for this webinar today. Visit www.nfpa.org/webinars for more upcoming NFPA & FPRF webinars and archives. When: Wednesday, April 14, 12:30 p.m. Eastern Time. Presenters: Brian Meacham, PhD, PE, Meacham Associates, and Margaret McNamee, PhD, Lund University.  This webinar is supported by the Research Foundation 2021 Webinar Series Sponsors: APA – The Engineered Wood Association AXA XL Risk Consulting Johnson Controls Reliable Automatic Sprinkler Co., Inc. Telgian Engineering and Consulting The Zurich Services Corporation

Fire Pump Types

Above credit: Hydraulics Institute Fire pumps are an essential part of many water-based fire protection systems. They are used to increase the pressure (measured in psi and bar) of a water source when that source is not adequate for the system it’s supplying. These are commonly found in buildings that tend to have a high-pressure demand such as high-rises or storage warehouses. This blog will review the different types of fire pump options available to designers. There are many types of fire pumps available. It is important to select the correct type of pump for the installation project to avoid excessive costs, and to avoid excessive pressures that might damage your system. If all the factors are not taken into consideration it could result in a pump installation that does not achieve the necessary pressure requirements which could require a new pump tobe installed. There are two main categories of pumps: positive displacement and centrifugal. Positive Displacement Pumps  Positive displacement pumps are characterized by a method of producing flow by capturing a specific volume of water per pump revolution and pushing it out through the discharge line. A bicycle tire pump is an example of a positive displacement pump we commonly see. Positive displacement pumps create very high pressures but have limited flow volume compared with centrifugal pumps. These are not as common because they have a specialized use, primarily with water mist and foam-water systems.  Centrifugal Pumps  Centrifugal pumps are the most common fire pumps and are used with most systems. With centrifugal pumps, pressure is developed principally by the action of centrifugal force or spinning. Water in centrifugal pumps enters the suction inlet and passes to the center of the impeller. The rotation of the impeller, in turn, drives the water by centrifugal force to the rim where it discharges. Centrifugal pumps can handle large volumes of water while providing high pressure boosts.  The following are different centrifugal type pump configurations: Horizontal Split-Case Pump With a horizontal split-case pump, the flow is split and enters the impeller from opposite sides of the pump housing. As the name implies, this is a pump installed with a split casing that can be opened for pump maintenance access and is connected to the driver by a horizontal shaft. They are very reliable, come in a wide range of rated flow and pressure capacities, are easy to maintain due to their relatively easy split-case access, and can be used with both electric and diesel drivers. However, these also typically need the most space of all types of fire pumps.  Credit: Hydraulics Institute    Credit: Grundfos Vertical Turbine Pump A vertical turbine pump is the only type of pump allowed by NFPA 20, Standard for the Installation of Stationary Pumps for Fire Protection that can start with negative suction pressure or take water under a lift condition such as from a below grade source such as a river or subgrade tank. These pumps can be used with raw water sources such as ponds, lakes, and rivers. Vertical turbine pumps come in a wide range of capacities and pressures, and they can be used with diesel and electric drivers.  In-Line Pump In-line pumps are useful where space is limited. These can be driven by both a vertical or horizontal shaft (end suction type). Vertical shaft types, which are the most common, have the driver located directly above the pump. These are typically one of the less expensive units and take the least amount of space but, they are also one of the more expensive to repair. Pump maintenance and repair can be difficult because the motor must be lifted off and removed to gain access to the pump, unlike a split-case unit. With these pumps, the suction flange and discharge flange are on approximately the same plane. In-line pumps have a limited capacity of typically no more than 1,500 gpm (5,678 L/min), and they can only be used with an electric driver which limits their potential applications.   Credit: Xylem - AC Fire Pump End Suction Pump An end suction pump has a discharge outlet perpendicular to the suction inlet. These pumps are typically limited to a capacity of approximately 1,500 gpm (5,678 L/min). Compared to horizontal split-case fire pumps, they are more compact and require less installation space in a fire pump room where available space is a concern. End suction pumps can be used with either an electric driver or a diesel driver. Multistage Multiport Pump Multistage Multiport pumps use a single-driver that can be either an electric motor or a diesel engine that connects to a pump with multiple impellers in series in a single casing driven by a horizontal shaft. The casing has multiple ports, or discharge outlets, delivering different pressures - each port has increased pressure from the consecutive series impellers. Credit: API International LLC / Western States Fire Protection Company For example, one multistage multiport pump could be installed in a high-rise building having 30 floors. The building may be divided into three zones where a multistage multiport pump equipped with three discharge outlets would use each outlet for a zone. The first has an outlet pressure of 100 psi (6.9 bar) and feeds lower floors or lower zone (ground to 9th), the second has an outlet pressure of 175 psi (12.1 bar) and feeds middle floors or mid zone (10th to 19th), and a third has a discharge pressure of 300 psi (20.7 bar) and feeds the upper floors or high zone (20th to 30th). Using multiport fire pumps could result in:  Fewer pumps required Less pipe work and fewer valves, as one pump could eliminate the need for some control valves and pressure reducing devices No requirement for water storage tanks on intermediate floors Lower structural loads and associated costs as only one pump may be required Energy conservation because less electricity and/or fuel will be consumed. Less pollution is also a potential benefit. Conclusion  Ultimately there are several different pumps that can be used in a variety of situations. When your system demand exceeds what your water supply can provide it’s time to look at what a fire pump can do to help bridge that gap. For more guidance see NFPA 20 for installation requirements and NFPA 25 Standard for the Inspection, Testing and Maintenance of Water-Based Fire Protection Systems, for ITM requirements.   Let us know in the comments below what your experience is when working with these systems. 
Gas

Research Foundation webinar recording on “Combustible Gas Dispersion and Detector Location Analysis in Residential Occupancies” is now available

There have been a handful of fuel gas explosions in the last five years including incidents that occurred in three rowhouses in northwest Baltimore in Aug 2020, in the Merrimack region of Massachusetts in 2018, and in Silver Spring Maryland in 2016. Listed fuel gas detectors and alarms exist, but there is no installation standard. Firm requirements are needed for installation of fuel gas detectors in residences and other occupancies. A new NFPA standard, NFPA 715 Standard for the Installation of Fuel Gases Detection and Warning Equipment is currently under development and will cover the selection, design, application, installation, location, performance, inspection, testing, and maintenance of fuel gas detection and warning equipment in buildings and structures. The Fire Protection Research Foundation facilitated a research project on combustible gas dispersion and detector location analysis in residential occupancies. The project was led by a research team at Gexcon US, and the deliverables from the study were presented in the Research Foundation’s most recent webinar on March 10, 2021. The research included a literature review of the existing guidance for combustible gas detector location and installation in residential occupancies, and computational fluid dynamics (CFD) simulations to clarify and strengthen the technical basis for combustible gas detector installation criteria in residential occupancies. CFD simulations were conducted to quantitatively evaluate gas detector performance as a function of placement in residential occupancies. Natural gas and liquefied petroleum gas releases were simulated in different residential structures, and gas concentrations are tracked at numerous potential detector locations within these structures to evaluate which locations are most effective for reliable and early detection. The full recording of this webinar is now available here. Visit www.nfpa.org/webinars for more upcoming NFPA and FPRF webinars and archives.  
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