Additive Manufacturing (3D Printing)

I recently came across an article about the first 3D printed house hitting the market in New York. While I’ve seen a lot of information regarding the benefits of 3D printing structures, mainly that it less expensive and faster than traditional construction methods, this was the first time I had seen a house that was actually 3D printed and being sold. It reminded me how quickly the 3D printing industry is expanding. The most recent edition of NFPA 1, Fire Code includes new language related to 3D printing or, more specifically, additive manufacturing.  One major distinction between the article and the language in the Fire Code is that the article is talking about structures that are 3D printed where as the NFPA 1 language addresses buildings that house additive manufacturing operations. Perhaps, as 3D printed structures become more popular the codes and standards may need to address unique requirements for them. Will there be special considerations when inspecting these types of structures, or will there be a limitation on the types of materials that can be used to print structures? Right now, the focus of requirements in the Fire Code is on protecting buildings that conduct additive manufacturing operations. Although you may have heard the term “3D printing” the Fire Code addresses “additive manufacturing.” Sometimes these are used interchangeably, but there is a difference. Additive manufacturing is the more inclusive term that encompasses all types of manufacturing that produce a product by adding material. Traditional manufacturing methods produce a product by removing material. The process starts with a block of material and pieces are removed and shaped until the desired shape is achieved. Here you can see how nails are made in a traditional manufacturing process. In additive manufacturing the process starts with nothing and material is added one thin layer at a time. 3D printing is one subset of additive manufacturing, but there are other types such as direct metal laser melting.  The Fire Code has two separate sets of requirements for additive manufacturing based on the associated hazard: industrial additive manufacturing and nonindustrial additive manufacturing.   Industrial Additive Manufacturing Industrial additive manufacturing processes are those operations that meet one of the following conditions: Use combustible powders or metals Use an inert gas supply Have a combustible dust collection system Create a hazardous electrical classification area outside of the equipment Nonindustrial Additive Manufacturing Nonindustrial additive manufacturing processes are those operations that meet all of the following: Do not use an inert gas supply Do not have a combustible dust collection system Do not create a hazardous electrical classification area outside of the equipment Differences in Requirements The use of combustible powders or metals, the use of an inert gas supply, or the creation of a hazardous electrical classification area outside of the equipment results in a higher level of hazard anticipated with industrial additive manufacturing than with nonindustrial additive manufacturing. Therefore, the requirements for industrial additive manufacturing and nonindustrial additive manufacturing are significantly different.  Location of Additive Manufacturing Nonindustrial additive manufacturing is permitted in all occupancy groups whereas industrial additive manufacturing is only permitted to be conducted in the occupancy groups associated with the manufacturing operations and as permitted by the maximum allowable quantity tables in NFPA 400. The fire and explosion hazards associated with industrial additive manufacturing are more aligned with the hazards you would see in a traditional manufacturing setting. However, many of those same hazards will not be found in nonindustrial additive manufacturing because of the differences in the operations. Therefore, those operations are permitted in a wider range of occupancies. Printing Powders The nonindustrial additive manufacturing operations are only permitted to use plastic filament production materials that are listed with the 3D printer and that are identified in the manufacturer’s instructions. The powders used in industrial additive manufacturing must be tested for combustibility in accordance with NFPA 484, Standard for Combustible Metals or NFPA 652, Standard on the Fundamentals of Combustible Dust. For industrial additive manufacturing operations additional requirements may need to be followed depending on the material used for production. For example, if a combustible, nonmetallic powder is used, then the operation must also comply with Chapter 40 of NFPA 1 and NFPA 654, Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing and Handling of Combustible Particulate Solids. Since these types of combustible materials are not permitted in nonindustrial additive manufacturing there are no similar requirements for those types of operations.  Gas Detection Industrial additive manufacturing processes that use inert gasses must have a gas detection system in all indoor areas where the inert gas is present. The gas sensors must be provided in areas where the gas is expected to accumulate and other locations where the AHJ requires them. The system must activate a supervisory audible and visible alarm upon detection of inert gas at the 8-hour time-weighted average concentration. There must also be an audible and visible alarm within the room or immediate area where the system is located and must automatically shut off the flow of the inert gas to the 3D printing equipment when the system detects inert gas at the threshold limit value-short-term exposure limit concentration. There are no comparable requirements for nonindustrial additive manufacturing since those processes are not permitted to use inert gasses. This summarizes the major differences between the two types of additive manufacturing addressed in the Fire Code. For specific details, you can view chapter 46 in NFPA 1. This new chapter provides a starting point for a technology that is changing rapidly and gaining in popularity every day.  Have you started seeing additive manufacturing in your jurisdictions? What are some of the challenges you’ve faced when it comes to this technology?
Gas

FPRF Webinar on “Combustible Gas Dispersion and Detector Location Analysis in Residential Occupancies”

This webinar will present the Fire Protection Research Foundation’s project conducted by the research team at GexCon on combustible gas dispersion and detector location analysis in residential occupancies. 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 were tracked at numerous potential detector locations within these structures to evaluate which locations are most effective for reliable and early detection. These research deliverables will support the development of a new NFPA standard, NFPA 715 Standard for the Installation of Fuel Gases Detection and Warning Equipment. The final report from the 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, March 10, 12:30 p.m. Eastern Time. Presenters: Scott G. Davis, Ph.D., P.E., GexCon US and Stephen Olenick, P.E. Combustion Science & Engineering, Inc. 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

A Guide to Fire Alarm Basics

A fire alarm system is a crucial part of the fire and life safety of a building and its occupants. There are many functions that are served by the fire alarm system and it all may be a bit confusing to someone new to fire alarms, so I decided to create a visual guide to fire alarm basics. The objective of this blog is to share that visual guide and to discuss some of the major components and functions of a fire alarm system. See larger image   FACU - Fire Alarm Control Unit The fire alarm control unit serves as the brain of the fire alarm system by monitoring all the inputs and controlling all the outputs. Some may also refer to this as a fire alarm control panel or fire alarm panel. The different types of conditions that can be seen at the fire alarm control unit are Alarm, Supervisory, and Trouble, these conditions can also result in a signal being sent to the supervising station. Alarm – An alarm condition means there is an immediate threat to life, property, or mission. An example of this would be a smoke detector sending a signal to the fire alarm control unit that there is a presence of smoke, which would initiate notification to the occupants to evacuate. Trouble - A trouble condition means there is an issue or fault with the fire alarm system. An example would be a break in an initiating device circuit. This would show up as a trouble signal on the control unit. Supervisory – A supervisory condition means there is an issue with a system, process, or equipment that is monitored by the fire alarm control unit (see supervision section). An example of this would be a sprinkler system valve being closed, this would show up as a supervisory signal on the control unit. Here is a blog discussing some of the places you may find a fire alarm control unit. The initiation of a fire alarm system includes all the devices and circuits that send a signal to a fire alarm to provide the status of a protected space or the existence of a fire. Initiation devices include, but are not limited to heat detectors, smoke 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 fire alarm control unit, the signals can be sent over an initiating device circuit (IDC) for conventional systems, or a signaling line circuit (SLC) for addressable systems.   Supervision It is possible to utilize a fire alarm system to monitor the condition of other systems, processes, or equipment that are related to the building’s fire and life safety as well as crucial to the mission of the building. Supervision can include but is not limited to valves on fire protection systems, other fire protection systems such as kitchen hood suppression systems, valve room or storage tank temperatures, and fire pump condition issues with these systems would provide a signal to the fire alarm control unit via an initiating device circuit (IDC) for conventional systems, or a signaling line circuit (SLC) for addressable systems and would create a supervisory condition at the fire alarm control unit.   Power It is important that a fire alarm system be provided with reliable power so it can operate during any emergency. Primary Power Primary power to the fire alarm system can be provided by the electric utility, an engine-driven generator (this is not a standby generator, however, it is a site generator meeting the requirements in NFPA 72® Fire Alarm and Signaling Code®), and Energy Storage System, or a cogeneration system. Secondary Power Secondary power to the fire alarm system can be provided via properly sized batteries, batteries and a standby generator, or an Energy Storage System.   Notification A fire alarm system is able to provide notification to alert the occupants and in some cases on site emergency forces. Notification is provided via visible and audible notification appliances. The visible notification is typically provided via strobes, and audible notification is provided by either speakers, which can provide different tones and voice signals, or horns, which can only provide a single tone. The fire alarm control unit provides the signal to the notification appliances via a notification appliance circuit (NAC).   Emergency Control Functions The fire alarm control unit can be used to control the function of other systems such as elevator recall, door closers, smoke control systems, and so on. The most common way that the fire alarm can do this is through the use of a control circuit and a relay.     Communication to Supervising Station Supervising stations monitor the premises and include Central Station Service, Proprietary Supervising Stations, and Remote Supervising Stations. The communication method to those supervising stations is done with the communication methods shown below. Based on the types of signals received from the fire alarm control unit and the type of supervision station, the supervising station may alert the emergency forces or dispatch a runner service to fix a trouble to supervisory condition. For more information on fire alarm supervision check out this blog.  I hope you found this guide to fire alarm basics informative, would you be interested in some more guides on other fire protection and life safety topics? If so, let me know in the comments below what systems or concepts you would be interested in. 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.
City snowy street

NFPA 25 provides guidance on maximizing fire safety during sprinkler systems restoration process

Over the past couple of weeks, one of the common themes among news stories and social media posts addressing the recent winter storms has been the impact of plunging temperatures on pipes. Numerous videos and images have shown frozen leaks extruding from systems and burst pipes allowing continuous flow of water from plumbing systems, which included all portions of automatic fire sprinkler systems. NFPA 13, Standard for the Installation of Sprinkler Systems, contains provisions that require protection of sprinkler system from freezing where exposure to low temperatures can be expected. Options for this protection, which have been addressed in previous blogs, include listed antifreeze solutions, the use of dry sprinklers or dry sprinkler systems, and heat tracing. While these are effective solutions when done properly and maintained in accordance with NFPA 25, Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems, these solutions are not typically provided in conditioned spaces where the heating system is expected to maintain temperatures above freezing. In the situation where utility outages and rolling blackouts disable the heating system, the water filled pipe in those heated areas can then be subject to extreme temperatures, causing the water to freeze and subsequent failures within the system. This is a situation beyond what the standard normally anticipates. Unfortunately, as those videos and images showed last week, many systems were subjected to record cold temperatures and suffered failures. 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 an impairment. In fact, one of the specifically identified ‘emergency impairments’ is frozen or ruptured piping. 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. Impairment Program In the time before the restoration of service, NFPA 25 provides details on impairment programs and what they should cover: Determination of the extent and expected duration of the impairment Determination of the area or buildings involved are inspected and increased risks Submittal 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 is removed The impacts of the recent weather events will be seen for a while, and as weather patterns throughout the U.S. become more extreme, these kinds of incidents will likely become more common. Taking the proper precautions and establishing a plan for handling these types of scenarios well ahead of time can make a tremendous difference in mitigating the impacts of extreme weather on sprinkler systems. NFPA offers a series of online trainings that can help ensure the effectiveness of sprinkler systems in multiple environments, including the upcoming NFPA 13 (2019) Live Virtual Training, which will held on March 8-12, 2021, and theNFPA 13, Standard for the Installation of Sprinkler Systems (2019) Online Learning Course.  
Leaking pipes

Frozen and burst/compromised pipes prompt concern around electrical safety for homes and other occupancies in the aftermath of Texas storm

Last week’s winter storm in Texas left millions of people contending with loss of power and heat, and in many cases, frozen pipes. For residents whose pipes burst, understanding the potential hazards posed by electrical wires and electrical equipment that come in contact with water is critical to safety.  Power should remain off until a professional electrician has inspected the entire home and all appliances, as water can damage the internal components in refrigerators, washing machines and dryers, causing shock and fire hazards. A qualified electrician can help determine what electrical equipment should be replaced and what can be repaired. In addition, people should always be directed to a qualified electrician if they have any questions or concerns around their home's electrical system.  The impacts of the Texas storm have reached far beyond homes, however, with many industrial and commercial facilities also facing concerns about their building's electrical systems. For building owners and managers working to assess water damage, critical decisions need to be made about whether the electrical equipment can be salvaged or not. NFPA offers a checklist to help highlight and simplify key aspects of this decision-making process. The checklist builds off recommendations in chapter 32 of NFPA 70B, Recommended Practice for Electrical Equipment Maintenance (2019 edition), which includes: A list of disaster scenarios, which can inflict damage of varying degrees to facilities Steps for assessing equipment A priority assessment table Steps to help identify factors for replacement or repair  While the choice between repair and replace is not always an easy one, following these simple suggestions can help turn what can feel like an impossible task into an informed decision.  In addition, NFPA offers its free “Natural Disaster Electrical Equipment Checklist” which serves as a valuable resource to community officials being asked for electrical information and assistance in the aftermath of a storm or other weather-related event.    Last but not least, a Facility Executive article written by NFPA’s Derek Vigstol talks about how facility managers can prepare for, respond, and recover from a disaster. Vigstol says that it all starts with prep work leading up to an event, which includes creating a site-specific disaster plan. This helps ensure the least amount of down time and a speedy recovery. Additional disaster-related resources for specialists tasked with protecting people and property from fire, electrical, and other emergencies, can be found on NFPA's disaster webpage, including bulletins, related code information, articles, and more.
Safety Stand Down

2021 Safety Stand Down Theme Focuses on Rebuilding Rehab

Firefighting puts intense strain on firefighters, both physically and mentally, and yet rehab frequently doesn’t get the consideration it should. Many think simply providing food and beverages to firefighters constitutes a rehab program. Thus, the reason that the focus of the 2021 Safety Stand Down campaign will be “Rebuild Rehab.” During the week of June 20-26, fire departments are advised to suspend all non-emergency activities to conduct training that helps responders reframe their thinking around rehab. In advance of that designated week, fire department leaders and trainers are asked to revisit their rehab program to ensure that post-incident and post-training protocol adequately addresses the health and safety of firefighters. Effective rehab programs evaluate both a firefighter’s physiological and psychological wellbeing and ensure that those on the front line are ready to respond to the next emergency. Rehab programs should encompass all areas of health, including cardiac, nutrition, exposure, mental health, hydration, and heat stress. Fire personnel can find best practices and benchmarks within NFPA 1584 Standard on the Rehabilitation Process for Members During Emergency Operations and Training Exercises. A wide array of topical information, training, and resources is also available at www.safetystanddown.org; the site will be updated periodically with new tips and tools leading up to Safety Stand Down in June so that departments can plan their education and awareness activities. Safety Stand Down is sponsored by the International Association of Fire Chiefs (IAFC) Safety, Health and Survival Section, the National Volunteer Fire Council (NVFC), and the National Fire Protection Association (NFPA). The awareness campaign is supported by national and international fire and emergency service organizations, including the Fire Department Safety Officers Association.  NFPA will once again launch a Fire Service Safety Stand Down Quiz this spring to foster a greater understanding of this year’s theme. Everyone who completes the online quiz will be automatically entered into a sweepstakes; 200 randomly selected participants will win a commemorative Safety Stand Down challenge coin. 
Houses under construction

Types of Construction and Material Combustibility

It is important to understand how a building will perform in a fire. Minimum construction requirements are established to help maintain structural integrity for the time needed for evacuation or relocation to a safe location in the building. The combustibility of a material gives an indication of how quickly a fire will grow. Both of these aspects are essential to fire and life safety.  NFPA 220, Standard on Types of Building Construction, defines types of building construction based on the combustibility and the fire resistance rating of a building's structural elements. When we talk about fire resistance rating, we mean the time, in minutes or hours, that materials or assemblies have withstood a fire exposure as determined by specific tests.  NFPA 101 requires certain occupancies to meet minimum construction requirements, which can be found in section 1, subsection 6 of any of the occupancy chapter (XX.1.6). NFPA 101 isn’t the only code that specifies minimum construction types, other codes, such as a building code will also specify minimum construction types. Often times the type of construction that the building is permitted to be made out of correlates to how many stories the building will have and whether or not the building will have sprinklers installed.  NFPA Construction Types NFPA 220 breaks down building construction into five different types which relate to the material, each one of these types is numbered one through five (in roman numerals). When codes and standards refer to the type of construction required or permitted there are three numbers in parenthesis that follow the type of construction. These numbers indicate the fire resistance rating in hours of different structural elements that are required. The image below gives an example of how you might see this rating in a document and explains the different types as well as the following numbers.  Type I: Noncombustible (or limited-combustible) construction with a high level of fire resistance, typically concrete construction.  Type II: Noncombustible (or limited-combustible) construction with a lower level of fire resistance than Type I, typically this is steel construction with or without fireproofing.  Type III: Exterior walls and structural elements are noncombustible or limited-combustible materials, and interior structural elements, walls, arches, floors, and roofs are wood that is smaller than what is required for Type IV construction. This is usually called ordinary construction and an example of this is a mixed masonry/wood building.  Type IV: Fire walls, exterior walls, and interior bearing walls are approved noncombustible or limited-combustible materials. Other interior structural elements, arches, floors, and roofs are solid or laminated wood or cross-laminated timber. There are certain dimensional requirements:  Columns – 8in (205mm) x 8in (205mm) if supporting floor, 6in (150mm) x 8in (205mm)  if supporting roof Beams – 6in (150mm) x 10in (255mm) if supporting floor, 4in x 6in (150mm) if supporting roof Arches – Varies 8in (205mm) x 8in (205mm) to 4in (100mm) x 6in (150mm) Floors – 3in (75mm) or 4in (100mm) thick  Type V: Structural elements, walls, arches, floors, and roofs are wood or other approved material. Most residential construction is Type V. First Digit (X00): Exterior bearing walls Second Digit (0X0): Columns, beams, girders, trusses and arches, supporting bearing walls, columns or loads from more than one floor.  Third Digit (00X): Floor construction Material Combustibility Outside of the construction type and fire resistance rating of the structural elements there are also different designations for what is considered a combustible material, limited combustible material and noncombustible material. Noncombustible Material Materials that pass the criteria in ASTM E136 when tested in accordance with either ASTM E136 or ASTM E2652 are considered noncombustible. Also, any inherently noncombustible materials can be considered noncombustible without having to be tested. Although the standard doesn’t explicitly say exactly what is inherently noncombustible the associated annex material goes on to suggest that it consists of materials such as concrete, masonry, glass and steel.  Limited Combustible Material Material that is considered limited combustible needs to meet certain criteria.  It needs to be able to produce a heat value less than 3,500 BTU/lb when tested in accordance with NFPA 259. (For context paper has a heat value of approximately 7,000 BTU/lb, wood is about 10,000 BTU/lb while most plastics are in the 15,000 to 22,000 BTU/lb range) Tested in accordance with ASTM E2965 at an incident heat flux of 75kW/m2 for 20 minutes and meet the following conditions. a. Peak heat release rate doesn’t exceed 150kW/m2 for more than 10 seconds b. Total heat released is less than 8MJ/m2 Either one of the following a. Material has a noncombustible base with a surface that doesn’t have a flame spread index greater than 50 when tested in accordance with ASTM E84. The surface ontop of the noncombustible base can’t be thicker than 1/8th inch (3.2mm) b. Flame spread index is less than 25 when tested with ASTM E84 or UL 723, even if the material is cut.  An example of a limited combustible material is gypsum wallboard.  Combustible Material Defining combustible materials is done so by process of elimination. If the materials don’t meet the definition of limited-combustible or noncombustible then it is a combustible material. A common example of a combustible material is untreated wood.  Ensuring a building remains structurally sound and that materials react to fire predictably is important to overall life safety. Understanding and complying with construction type requirements is the first step in creating a safe built environment. We gave some common examples of each type of construction, what are some other examples? Let me know in the comments below. 
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