Topic: Industrial Hazards

plant fire

Recent NC Fire Shines Light on Gaps in Ammonium Nitrate Regulation That No Longer Can be Ignored

With the flames of a North Carolina January 31 fertilizer plant fire now safely extinguished, it’s now time for local, state, and federal officials to focus on fixing the holes that govern ammonium nitrate (AN) storage and handling. On April 17, 2013, a fire in Texas led to the detonation of about 30 tons of AN and the deaths of 15 people, along with the injury of hundreds more, and major destruction to the town of West. Nine years later, the city of Winston-Salem, North Carolina came dangerously close to experiencing the same fate. The fact that fate was avoided should not mean we avoid addressing this issue. In its final report on the West, Texas tragedy, the U.S. Chemical Safety Board (CSB) observed, “This is not to say that West is an anomaly. Many communities in Texas and nationwide are located too close to facilities resembling the [West Fertilizer Company] plant.”[1] The Winston Weaver Fertilizer plant is exactly the situation the CSB was referring to. Like the facility in West, the North Carolina plant began operating mid-century, surrounded by farmers’ fields and few neighbors. Over time, homes, businesses, and other buildings sprung up around it as the town grew. The pattern, both in West and in Winston-Salem is not unique. The American Farmland Trust reports that over 11 million acres of U.S. farmland have been developed over the last 20 years, putting homes and suburban infrastructure next to facilities that manufacture, store, and sell fertilizers and other chemicals. Local planners in places like Winston-Salem, which grew by around 8 percent over the last 10 years, must recognize this hazard and limit development around these locations to compatible uses, like warehouses, not homes and school.  When the fire broke out at the Winston Weaver Fertilizer plant, the fire department promptly called for an evacuation of the surrounding neighborhoods, fearing the detonation of the plant’s 600 tons of AN. Over 6,500 people left their homes in the middle of the night. In addition to a well-prepared fire department though, towns and cities have another tool to save lives and property from hazardous materials like AN—the fire code. When handled and stored properly, AN can be stable. But, when exposed to fire, there is a significant danger of a powerful explosion (see for instance, the recent blast that leveled a portion of Beirut, Lebanon). Recognizing, as the CSB did, that the hazard present in West, Texas was not unique, the technical committee that develops NFPA 400, the National Fire Protection Association’s Hazardous Materials Code, determined fire sprinkler systems in these facilities is a must. They voted in 2015 to make the installation of sprinkler and fire detection systems in new and existing facilities a requirement of the accepted minimum level of safety for any building with over 1000 pounds of AN. The NFPA fire code, NFPA 1, refers users to NFPA 400 for facilities storing AN, and expressly enables the relevant authority to enforce construction requirements—like sprinklers systems—retroactively when warranted by dangerous conditions. Unfortunately, in many places, the laws in place are not this proactive. In the case of Winston-Salem, the North Carolina state fire code does not require facilities like Winston Weaver to meet NFPA 400’s requirements. However, the fire that occurred on January 31st should prompt the North Carolina legislature to require NFPA 400’s retroactive fire protection requirements, especially where an explosion poses a risk to surrounding homes, businesses, schools, hospitals and other community facilities. It should also prompt the North Carolina Building Code Council to amend the state fire code to include the NFPA 400 requirements. Even if the state does not act though, local governments in North Carolina are not powerless. State law permits local jurisdictions to adopt their own fire code provisions so long as those provisions are stricter than those promulgated by the state. In addition to ensuring fire code protection, the CSB made a number of other recommendations to reduce the risk of another West-type catastrophe. For one, state legislatures could enact laws that would require facilities like the Winston Weaver Fertilizer plant to hold general liability insurance policies commensurate with the risk they pose to their surroundings. The CSB investigation revealed that four years before the explosion, West Fertilizer Company (WFC) was dropped by its insurance carrier for failure to address a number of safety concerns identified by the insurer’s inspection process. The $1 million general liability policy WFC turned to instead came with minimal safety inspections. After the explosion, the policy was woefully inadequate to redress the $230 million-plus damage to the town and its residents. More stringent insurance requirements would motivate greater due diligence in identifying and controlling hazards. At the federal level, CSB made recommendations to several agencies. Among those was a call to the Environmental Protection Agency (EPA) to add AN to the list of chemicals covered in its Risk Management Program (RMP). Developed in the 1990s, the RMP regulations require facilities handling listed chemicals to assess the potential worst-case scenarios for communities beyond the fence line, implement hazard controls, and report on these to the agency. As the CSB pointed out, AN’s reactivity, its potential to cause high loss of life, and its presence in high volumes at sites across the country all favor its inclusion on the RMP list. Unfortunately, nearly a decade after the West incident, many of these recommendations remain open. Texas did not adopt stricter insurance requirements and the EPA still hasn’t added AN to the list of chemicals covered by the RMP. However, the EPA’s announced plans to improve health and safety conditions for people living in fence line communities presents an ideal opportunity to revisit how we handle and store AN, and other hazardous materials, and reduce the risk of catastrophic accidents for all communities. North Carolina too must not wait to identify other AN hazards in the state and enact the policies discussed here to prevent another close call—or worse.   [1] U.S. Chemical Safety Board, Investigation Report: West Fertilizer Company Fire & Explosion, January 2016, p 223. [1] § 143-138(e)

Commodity Classifications in NFPA 13

Commodity classifications are used to categorize the contents of storage occupancies so that the appropriate sprinkler system design can be identified. Commodity classifications are determined by not only the product but also the packaging of that product, the container those packaged products are in, and even the pallet type. This can get a little complicated, so I’ll run through a quick example. We have glass jars stored in a double layered carboard box with cardboard dividers and it is sitting on a reinforced plastic pallet. Even though the glass jars are only a Class I commodity, the cardboard box and plastic pallet increases the fuel load so that it should be considered a Class IV. Commodity Classifications are broken down into Classes I through IV and Group A though C plastics with Class I being the lowest hazard level and Group A expanded plastics being the highest hazard level. Class I: A Class I commodity is defined as a noncombustible product that meets one of the following criteria: Placed directly on wood pallets Placed in single-layer corrugated cardboard boxes, with or without single-thickness cardboard dividers Shrink-wrapped or paper-wrapped as a unit load Class II: A Class II commodity is defined as a noncombustible product that is in slatted wooden crates, solid wood boxes, multiple-layered corrugated cardboard box, or equivalent combustible packaging material. Class III: A Class III commodity is defined as a product fashioned from wood, paper, natural fibers, or Group C plastics with or without cartons, boxes, or crates. A Class III commodity shall be permitted to contain a limited amount (5 percent or less by weight of nonexpanded plastic or 5 percent or less by volume of expanded plastic) of Group A or Group B plastics. Class IV: A Class IV commodity is defined as a product that meets one of the following criteria: Constructed partially or totally of Group B plastics Consists of free-flowing Group A plastic materials Cartoned, or within a wooden container, that contains greater than 5 percent and up to 15 percent by weight of Group A nonexpanded plastic Cartoned, or within a wooden container, that contains greater than 5 percent and up to 25 percent by volume of expanded Group A plastics Cartoned, or within a wooden container, that contains a mix of Group A expanded and nonexpanded plastics and complies with the graph section at the end of the blog Exposed, that contains greater than 5 percent and up to 15 percent by weight of Group A nonexpanded plastic Exposed, that contains a mix of Group A expanded and nonexpanded plastics and complies with the graph section at the end of the blog PLASTICS Plastics are a little more straightforward since there is a specific list of what each group contains. Classifying plastics gets complicated when the commodity being stored is a combination of different groups of plastics, but the graphs at the end of this blog should be able to help alleviate some of that work. Group C Plastics: Group C plastics are treated as Class III Commodities and consist of the following: Fluoroplastics (PCTFE — polychlorotrifluoroethylene; PTFE — polytetrafluoroethylene) Melamine (melamine formaldehyde) Phenolic PVC (polyvinyl chloride — flexible — PVCs with plasticizer content up to 20 percent) PVDC (polyvinylidene chloride) PVDF (polyvinylidene fluoride) Urea (urea formaldehyde) Group B Plastics: Group B plastics are treated as Class IV Commodities and consist of the following: Chloroprene rubber Fluoroplastics (ECTFE — ethylene-chlorotrifluoro-ethylene copolymer; ETFE — ethylene-tetrafluoroethylene-copolymer; FEP — fluorinated ethylene-propylene copolymer) Silicone rubber Group A Plastic: Group A plastics are further subdivided into expanded and nonexpanded Group A plastics and consist of all of the plastics listed in the table below. ABS (acrylonitrile-butadiene-styrene copolymer) FRP (fiberglass-reinforced polyester) Polycarbonate PVC (polyvinyl chloride — highly plasticized, with plasticizer content greater than 20 percent) (rarely found) Acetal (polyformaldehyde) Natural rubber Polyester elastomer Acrylic (polymethyl methacrylate) Nitrile-rubber (acrylonitrile-butadiene-rubber) Polyethylene Butyl rubber Nylon (nylon 6, nylon 6/6) Polypropylene PVF (polyvinyl fluoride) Cellulosics (cellulose acetate, cellulose acetate butyrate, ethyl cellulose) PET (thermoplastic polyester) Polystyrene SAN (styrene acrylonitrile) EPDM (ethylene-propylene rubber) Polybutadiene Polyurethane SBR (styrene-butadiene rubber) HELPFUL DEFINITIONS One of the biggest issues I see when people are starting to learn about sprinkler design for storage occupancies is that they don’t know the terminology. It is important to fully understand the definitions for the terms used in the storage chapters of NFPA 13, Standard for the Installation of Sprinkler Systems. I recommend looking at the definition chapter of NFPA 13 to make sure you understand exactly what a term means because oftentimes it means something different than what you would expect. Here are a couple of definitions that are important to understanding this blog. Expanded Group A Plastics: Those plastics, the density of which is reduced by the presence of air pockets dispersed throughout their mass. Some examples include packing peanuts or acoustic foam. Nonexpanded is everything else that is not covered under the definition of expanded. Free Flowing Group A Plastics (protect as Class IV): Those plastics that fall out of their containers during a fire, fill flue spaces, and create a smothering effect on the fire. Examples include powder, pellets, flakes or random-packed small objects. Free flowing plastics are those small objects that fill a box or a subdivision within the box without restraint. The theory is that during a fire. The objects will freely fall out of the box and either smother the fire or fall away from it, removing themselves as fuel. Since the burning rate is reduced and fuel load has been lessened, free-flowing plastics are permitted to be treated as a Class IV commodity. Exposed: Commodities not in packaging or coverings that absorb water. For example, a cardboard box or wooden container can both absorb water so they would not be considered exposed. However, something that is wrapped in plastic sheeting could be considered exposed since plastic sheeting doesn’t absorb water. Cartoned - A method of storage consisting of corrugated cardboard or paperboard containers fully enclosing the commodity. GRAPHS The following tables come from NFPA 13 to help with navigating how a commodity should be classified when it contains Group A plastics. Note that the X axis is percentage by volume while the Y axis is percentage be weight.  The first graph addresses exposed commodities while the second graph addresses commodities that are cartoned or within a wooden container (non-exposed). PALLETS When commodities are tested, they are tested on wooden pallets. This means that wooden pallets are assumed to be used in commodity classifications, however if plastic pallets are used, they increase the commodity classification by two classes. Although, if the plastic pallet is made of polypropylene or high-density polyethylene and marked as “nonreinforced” then the commodity classification only needs to be increased by one classification. Plastic Pallet Increase (+2) Class I --> Class III Class II --> Class IV Class III --> Group A Plastics Class IV --> Cartoned nonexpanded Group A plastic Group A Plastics --> Group A Plastics (No increase)  Unreinforced Polypropylene or High-Density Polyethylene Plastic Pallet Increase (+1) Class I --> Class II Class II --> Class III Class III --> Class IV Class IV --> Cartoned nonexpanded Group A plastic Group A Plastics --> Group A Plastics (No increase) Determining the classification for commodities in storage occupancies can get complicated at times but I can not stress how important of a step this is during the sprinkler design process. It is also imperative that the owner understands what the building is designed to handle as well as what can and can not be stored in the facility once it is built. I hope you enjoyed the blog. Comment below if you have questions and be sure to share this with friends and colleagues who might find it helpful.

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

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

Unique Fire Protection Challenges Found in Warehouse/Distribution Centers

NFPA research shows that warehouse fires happen at a frequent rate with an average of 1,410 warehouse fires, two deaths, 20 injuries, and an estimated $159.4 million in direct property damage annually. To avoid becoming part of these statistics it is essential that a fire protection system is correctly designed, installed, inspected, maintained, and tested. Warehouse environments require additional considerations for sprinkler system design. This is due to the nature of how warehouses are designed and used. This blog will look at a handful of unique fire protection challenges found in warehouses and other distribution centers. For more specific information on how to design a sprinkler system see NFPA 13, Standard for the Installation of Sprinkler Systems. Commodity classification The most obvious unique characteristic of a warehouse is that the purpose of the building is to store a large number of goods and products. This can increase the fire load by a significant amount. This is why it is essential, when designing an automatic sprinkler system for a warehouse, that the items being stored are assigned the proper commodity classification. When determining the commodity classification, it is important to include not only the product itself but also the packing material as well as the container and pallet. The different commodity classifications are as follows: Class I – a noncombustible product that is either stored in single layer cardboard boxes or shrink wrapped or paper wrapped. The product can either be stored with or without wooden pallets. Class II – A noncombustible product stored in either wooden crates or multiple-layered cardboard boxes. The product can either be stored with or without wooden pallets. Class III – A product made from wood, paper, natural fibers, or Group C plastics. This can be stored with or without wooden crates and pallets. Class IV – A product that can be made from a mixture of Group B plastics with wood, paper, natural fibers or Class C plastics. The product is allowed to be made from a small percentage of Group A Plastics Group C Plastic – Certain plastics such as PVC. This is treated the same as a Class III Commodity Group B Plastic – Certain plastic rubbers such as silicone. This is treated the same as a Class IV commodity. Group A Plastic -   The most flammable plastics and natural rubbers. This group is further subdivided into expanded or nonexpanded plastics. This is treated differently from all other commodity classifications. In rack sprinklers Warehouses are the only location where you will find sprinklers both at the ceiling level as well as in racks closer to ground level. This is a unique way to get water in the racks and applied to a fire before it is able to grow beyond the capabilities of the sprinkler system. Some higher hazard commodities will require in-rack sprinklers while other commodities have the option to include rack sprinklers and decrease the robustness of the ceiling sprinklers. Prewetting Most sprinkler systems rely on the concept of prewetting as a critical component in controlling a developing fire. Prewetting is when the sprinkler system activates and wets the fuel in front of the fires path, slowing down the fire growth. The issue with warehouses is that they can contain encapsulated products, which are impervious to prewetting (think of something that is wrapped in plastic on all sides). Due to this challenge the sprinkler system would have to be designed to be robust enough to be able to control a fire without prewetting. Obstructions In warehouses there is the potential for Early Suppression Fast Response (ESFR) sprinklers to be used. ESFR sprinklers rely on getting water to the fire quickly, this means both activating earlier than normal sprinklers and discharging water at a higher velocity. Because of this unique design feature, it makes it even more important to ensure that these sprinklers are clear of obstructions. If the sprinklers were prevented from reaching the fire during the early stages of fire growth the sprinkler could be ineffective. Change management Warehouses are likely to have items with varying commodity classifications being stored. Sprinkler design can account for this by either designing to the highest hazard commodity or by creating separate zones for higher and lower hazard commodities. Either way, when warehouses change what they are storing it is essential that the new products do not exceed the hazard level that the sprinklers were designed for. Flammable liquids and gasses Another unique fire protection challenge for warehouses is that there might be large quantities of hazardous materials such as flammable liquids and gasses. These types of materials typically fall outside of the scope of NFPA 13 and into other NFPA documents such as NFPA 30, Flammable and Combustible Liquids Code, NFPA 55, Compressed Gases and Cryogenic Fluids Code, NFPA 52, Vehicular Natural Gas Fuel Systems Code or NFPA 58, Liquified Petroleum Gas Code. These codes contain requirements on the specific containers, building construction, and/or sprinkler design required for the storage of these more hazardous materials. These are just some of the many unique fire protection challenges for warehouse and other similar distribution centers. For more information check out our Warehouse Fact Sheet. Also, come check out NFPA’s 125th Anniversary Conference series on November 16, which will feature presentations on automatic warehouse storage and retrieval systems, the importance of water supply assessment, a review of the changes to the 2022 edition of NFPA 13, and other relevant systems, storage, and suppression topics. Buybox:Title:Featured training|OLS1322SPR

Hazardous Materials Identification

There are boundless amounts of hazardous materials that present increased risks to people exposed to them, whether building occupants, people in nearby structures, or first responders. These materials vary greatly in their composition and physical states. The risks, or hazards, associated with these materials are even more varied and must be assessed for a particular material in the state and manner in which it will be stored or handled. With such a wide range of materials and hazards there is also great diversity in construction requirements, fire protection systems, handling and operations, and response tactics associated with these materials. Here we will focus on the system of markings that provides a general idea of how hazardous materials need to be identified. What is a Hazardous Material? Before discussing the specifics of hazardous materials identification, it can be beneficial to know what is considered a hazardous material. Hazardous materials are defined in NFPA codes and standards as chemicals or substances that are classified as a physical hazard or a health hazard. Physical hazard materials are those classified as an explosive, flammable cryogen, flammable gas, flammable solid, ignitible liquid, organic peroxide, oxidizer, oxidizing cryogen, pyrophoric, unstable (reactive), or water-reactive material. Health hazard materials are those classified as a toxic, highly toxic, or corrosive material. How do hazardous materials need to be identified? NFPA 704, Standard System for the Identification of the Hazards of Materials for Emergency Response, specifies the identification requirements for these materials. NFPA 704 applies when another Federal, state or local regulation or code requires its use. NFPA 704 does not specify when a container, tank or facility must be labeled rather it specifies how to label when another code, standard or an AHJ (Authority Having Jurisdiction, such as the local fire department) requires such labeling. The standard applies to industrial, commercial, and institutional facilities that manufacture, process, use, or store hazardous materials. It does not apply to transportation, use by the general public, and a few other specific uses. The purpose of the standard is to provide a simple, readily recognized, and easily understood system of markings that provides a general idea of the hazards of a material and the severity of the hazards as they relate to emergency response. The identification system specified in NFPA 704 is intended to enable first responders to easily decide whether to evacuate the area or to commence emergency control procedures and to also provide information to assist in selecting firefighting tactics and emergency procedures. The NFPA 704 hazard identification system is characterized by a diamond which is more precisely defined as a “square-on-point” shape. It identifies the degree of severity of the health, flammability, and instability hazards. Hazard severity is indicated by a numerical rating that ranges from zero (0) indicating a minimal hazard, to four (4) indicating a severe hazard. The hazards are arranged spatially such that health hazards are indicated in the nine o’clock position, flammability at the twelve o’clock position, and instability at the three o’clock position. The six o’clock position on the symbol represents special hazards and has a white background; it is not always filled. W Water reactivity (avoid the use of water) OX Oxidizer SA Simple asphyxiant (nitrogen, helium, neon, krypton, or xenon)   As an example, the following would be used for propane gas which has a moderate health hazard, a severe flammability hazard, is normally stable, and does not require any special labeling. Another example is for liquid oxygen which can present a serious health hazard under emergency conditions, is not flammable, is stable, and is an oxidizer.\       Where do signs need to be located? The placard is meant to provide quick hazard information for emergency responders. It should be visible in case of an emergency where the responders are likely to enter. If there are numerous areas where the responders could enter the facility, there should be numerous placards. The placement and quantity should be decided using a facility’s best judgment coupled with the advice from your AHJ. At a minimum the placard should be posted on the two exterior walls of a facility or building, each access to a room or area, or each principal means of access to an exterior storage area. Other Considerations As mentioned at the start of this discussion there are many additional considerations regarding hazardous materials. Even within this topic of identification there is a lot more to it than what has been simplified in this blog. Check out this collection of NFPA 704 frequently asked questions for more information. Beyond that there are construction, maximum allowable quantities, fire protection system, and worker exposure requirements just to name a few. Additionally, each of these will vary based on the nature of the material(s) being stored or used. If you want more detail on identification or any of the other topics around hazardous materials, let us know in the comments.

Transformer Fire Protection

While superheroes and the big box office may have everything thinking about robots when we talk about transformers, they are actually a much more important device that is essential for the transmission, distribution, and utilization of alternating current electric power. What are transformers and what do they do? In basic terms a transformer is a device that transfers electric energy from one AC circuit to another, either increasing or reducing the voltage. This is done for several reasons, but two main purposes are to reduce the voltage of conventional power circuits to operate low-voltage devices and to raise the voltage from electric generators so that electric power can be transmitted over long distances. They have been in use for a long time and are an essential piece of our electrical infrastructure. The most common transformer that people often see are located on telephone poles. Why are transformers hazardous? Transformers are often times filled with oil for insulation, to prevent electrical arcing and to serve as a coolant. This oil is similar to mineral oil and very flammable. When a transformer fails it can lead to an intense fire and violent explosion (feel free to check out one of the many videos online on exploding transformers). Transformers can hold anywhere between a few gallons to thousands of gallons. Transformers can be installed indoors or outdoors, but indoor transformers typically are not filled with oil while outdoor transformers often are. Oil insulated transformer protection methods Some of the main considerations when talking about transformer fire protection are fire walls & separation, water based fire protection systems, containment, drainage and lightning protection. Fire Wall & Separation Ideally, we want to prevent transformers from catching fire, but in the event one does catch fire or explode we want to limit the damage and potential spread of fire. This can be done by several means, the most common being physical separation and fire walls. NFPA 850, Recommended Practice for Fire Protection for Electric Generating Plants and High Voltage Direct Current Converter Stations,  recommends that transformers with more than 500 gallons (1900 L) of oil be protected by a fire wall rated for 2 hours that is extended 1ft (300 mm) vertically and 2ft (600 mm) horizontally beyond the transformer. In lieu of a fire wall, physical separation is recommended anywhere from 5 to 25 ft (1.5 to 15 m) based on the oil capacity of the transformer. Fire Protection Systems NFPA 15, Standard for Water Spray Fixed Systems for Fire Protection, contains requirement on how transformers should be protected using a water spray system. If requires  0.25 gpm/ft2 [10.2 (L/min)/m2] of water to be discharged onto the envelope of the transformer itself and 0.15 gpm/ft2 [6.1 (L/min)/m2]  on the surrounding area for exposure protection. The water supply for such a system needs to be able to keep up with the designed flow rate of the system as well as 250 gpm (946 L/min) for a hose for the duration of 1 hour. Another important protection feature is a containment pit and drainage system to help retain any spilt transformer oil or discharge from a fixed water spray system. If a containment area is designated, then the fire wall should at least extend to the edge of that area. Since lightning is a potential ignition source for a transformer fire lightning protection should also be provided. For more information on how lightning protection works see NFPA 780, Standard for the Installation of Lightning Protection Systems. Transformer failures can be extremely dangerous but with the right precautions in place fires can be controlled to limit damage to the surrounding components, minimize plant downtime and improve survivability of plant staff. There is a lot more that goes into panning and designing a safe transformer installation, but this addresses the main concepts and ideas. For more information on fire protection recommendation for power generating plants check out NFPA 850, Recommended Practice for Fire Protection for Electric Generating Plants and High Voltage Direct Current Converter Stations.
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