NIST logo
*
Bookmark and Share

Reduced Flammability of Upholstered Furniture Project

Summary:

The long term vision for this project is to enable the prediction of the burning behavior of furniture based on the material properties and the furniture construction details. During Phase 1 of this project (FY12-FY14), burning behaviors of upholstered cushion mock-ups constructed from a range of materials are being characterized and correlated with corresponding burning behaviors for reduced scale samples in the cone calorimeter. This knowledge will provide the foundation for the prediction tool based on component analysis (Phase 2) and will empower furniture manufacturers1 to design and manufacture units with quantifiable fire behavior improvements. These improvements will result in slower fire growth and significantly reduce the risk of flashover, which is associated with a majority of fire losses in residences. In order to meet the current and long term project objectives, the Phase 1 project has been separated into four tasks. (1) Improving the quantitative understanding of the role of upholstered furniture in fire growth and spread in residences and the resulting losses. (2) Providing improved robustness and sustainability for the existing reduced ignition propensity (RIP) cigarette test method, while at the same time developing the measurement foundation for a more effective future standard. (3) Improving the understanding of smoldering and transition to flaming in RUF. (4) Developing tests for and providing a better understanding of the effectiveness of barrier fabrics for use in RUF and providing the foundation for standard test methods for the effectiveness of such materials.

Description:

Objective: By 20152, to develop the measurement science to (1) enable predicting the peak heat release rate of upholstered cushions based on the material properties of the components used in their construction (2) quantify fire losses due to flaming residential upholstered furniture (RUF), (3) maintain a standard for reducing RUF ignition by cigarettes, (4) quantify the effectiveness of fire blocking barrier fabrics, and (5) improve the understanding of smoldering in RUF and transition to flaming.

What is the new technical idea? The burning behavior of RUF is widely recognized as a dominant factor in the ignition, spread, and growth of building fires, particularly residential fires, which account for 80% of fire deaths and property losses3. The findings of a recent NIST Workshop confirmed the important role of flaming residential upholstered furniture (RUF) in fire losses and provided a path forward to quantify its contribution4. An analysis performed by NFPA and USFA as a direct result of the workshop and sent to the workshop organizer in the form of a letter report provides the first quantitative estimate for the role of flaming RUF in fire losses when RUF is not the first item ignited5. Significantly, flaming fires (both as first and later item ignited) are estimated to be responsible for roughly half of the amounts of deaths, injuries, and financial losses as those due to fires in which RUF is directly ignited by smoldering sources. This estimate, when combined with the Workshop conclusion that the vast majority of fire losses associated with RUF fires started by smoldering ignition occur after transition to flaming, confirms that the flaming burning behavior of RUF is the dominant factor in fire losses associated with RUF burning. Most prior attempts to curb the contribution of RUF to fire losses have consisted of limiting ignition, primarily smoldering ignition. As a result of concerns about the toxicity of flame retardants currently used in RUF, the only standard in the United States directly addressing flaming burning behavior of RUF (California TB 117)6 is currently being amended to address primarily smoldering ignition. Due to the central role flaming RUF plays in fire losses, this project is focused on providing the understanding and tools required to reduce the ignition of, the growth rate, and the heat release rate of these flaming fires7.

Whole item fire tests of RUF, which are time consuming and costly, are impractical due to the wide range of styles and materials used along with rapid, fashion-driven changes in upholstery materials. Relatively small numbers of a given RUF design and material combination are generally produced. The development of a technically sound furniture design tool based on characterized physical and combustion properties of the furniture components will be required by furniture manufacturers to produce RUF meeting potential future regulations based on limiting the heat release rate of RUF. Such a design tool will enable RUF manufacturers to identify the materials and configurations necessary to produce furniture with desired levels of fire performance. By designing furniture that is incapable of generating sufficient heat release rate (to be characterized as part of this project) to initiate flashover in a room, the likelihood of flashover, with its associated fire losses, in residences will be substantially reduced.

The new technical idea is to develop capabilities to understand various aspects of the fire behavior of RUF and then combine these approaches to form the required tool. The validity of this approach will be demonstrated in the current project by applying it to the fire behavior of upholstered cushions, an important subcomponent of RUF. An approach will be developed to predict the maximum heat release rate of upholstered seat cushions constructed from a wide range of materials characterized by carefully chosen small-scale laboratory tests. The project is in direct alignment with the strategic roadmap on innovative fire protection8.

What is the research plan? This is the last year of the first phase of this project. The landscape for the project has changed dramatically since its inception due to recent widespread public discussion of the toxicity of the fire retardants currently used in American RUF and the resulting calls for change by the public, regulatory agencies, members of Congress, and state governments. Three recent workshops have highlighted these issues9,10,11. This public focus on RUF has vastly increased the immediate need for NIST findings as well as raising the visibility and scrutiny of our efforts. The public discussion, workshops, and individual discussions with workshop attendees from government and the private sector highlighted areas where additional research is required and provided an important opportunity to reassess our working hypotheses and research plans. While leading us to tweak our current research efforts, as incorporated in this FY14 project plan, this self-assessment confirmed the appropriateness and value of our adopted research approach.

The major working hypothesis has been that component analysis can be used as the basis for a design tool having sufficient fidelity to predict effects of design changes on fire spread and growth on RUF. This hypothesis is being tested by assessing the degree of correlation of small-scale composite tests with the burning behavior of upholstered cushions mocked up as chairs. Upholstered cushions themselves are a component of RUF. They have been chosen for initial demonstration of the approach in order to limit the wide range of geometric and material effects expected for actual RUF. Cushions to be tested are being produced from a variety of commonly used padding materials, barrier fabrics, fiber fills, and fabrics chosen to span a wide range of flammability properties. Component materials and composites have been subjected to small scale tests (cone calorimeter) designed to characterize their response to fire. During FY14 the major milestone is an assessment of the effectiveness of cone calorimeter measurements for predicting the burning behavior of real scale cushion mock-ups. These findings will be used as the basis for a critical analysis of other parameters that will need to be addressed during the development of the tool for RUF manufacturers.

In addition to the work addressing the overarching goal of predicting the fire behavior of RUF, a number of more focused, shorter term efforts dealing with specific aspects of the RUF fire problem are being conducted concurrently. While these efforts are generating knowledge that contributes to the overall goal, perhaps more importantly, they are designed to answer important short term research needs and/or provide the measurement science to support tests and standards development. The following paragraphs detail these tasks.

Task 1 will quantify the impact residential upholstered furniture has on fire losses. This will be accomplished by using the existing fire statistics to estimate fire losses and modeling to estimate the contribution of RUF to flaming fire growth in enclosures. The three-year goal is to provide a vastly improved quantitative understanding of the role flaming RUF plays in fire residential fire losses. In year 1 (FY12), NIST organized a workshop in which participants proposed an approach for using existing National Fire Incidence Reporting System (NFIRS) data to estimate residential fires losses associated with flaming RUF4. Based on this guidance, researchers at NFPA and the US Fire Administration have developed and implemented the new approach that is providing a more accurate estimate of residential fire losses associated with RUF fire behavior. In year 2 (FY13), the results of the NFPA and USFA have been released in a revision of the workshop report. At the same time NIST is working to confirm and refine these estimates. We have also started using CFAST to understand the contribution of RUF to developing enclosure fires. In year 3 (FY14), NIST will deliver a CFAST analysis that will predict the maximum RUF heat release rate sufficient to prevent flashover12 in compartment fires.

Task 2 will provide the technical basis for improving the existing reduced ignition propensity (RIP) cigarette standard. Cigarettes are the leading cause of direct ignition of RUF. Legislation requiring the use of RIP cigarettes has been adopted by all fifty states, which is believed to be significantly reducing the associated fire losses. In the first two years (FY12-13), NIST has been evaluating new materials to use as a substrate13 for the standard test used to evaluate the self-extinguishing behavior of cigarettes. In a related effort, NIST has been working with CPSC support to identify an appropriate alternative to replace the NIST SRM cigarette14 used in the current standard. In year 3 (FY14), NIST will coordinate and participate in round-robin testing of the proposed new substrate. The findings will be shared with the appropriate standards committees. NIST will also develop a research plan to address the development of a more effective RIP cigarette.

Task 3 will provide an improved understanding of the decades-old standard fabric test used as the basis for smoldering RUF regulations and determine which factors influence transition of smoldering RUF to much more dangerous flaming combustion. FY13 was the first year of this task, which was initiated in response to research needs identified during the three recent workshops9,10,11 on furniture flammability. Questions have arisen concerning the degree of correlation between existing and proposed small-scale standard mock-up tests of cigarette ignition and the real world behavior of upholstered furniture. The current effort builds on an earlier long-term effort in the Fire Research Division, sponsored by CPSC, on the development of a standard flexible polyurethane foam (FPUF) for cigarette ignition testing. In year 2 (FY13), the controlling parameters for small scale mock-ups smoldering ignition are being investigated and will be used as the starting point for understanding the transition from smoldering to flaming in FY14. This will be done by measuring mass loss and temperature in the foam as a function of changes in materials parameters, such as of the foam (e.g., surface area) and fabric (e.g., high loft woven).

Task 4 will develop the measurement science that enables selection and standardized testing of barrier fabrics (BF) for use in RUF. Fire blocking barrier fabrics appear to be the most promising technology for compliance with any future proposed flaming RUF regulations and appear to satisfy EHS15 concerns as no fire retardants are necessary in the product11. In FY12-13, more than 25 commercial BFs were tested for open flame resistance and characterized using a range of tools (e.g., TPP and Cone Calorimeter). Attributes critical to good performance were identified along with several tests that we believe should correlate with performance in full-scale RUF flammability tests. The testing guidelines and a database of performance values were published as a NIST Technical Note and shared at the recent CPSC meeting on fire barriers for RUF11. In FY14, the focus will be on smolder ignition resistance of BFs as a component and used in a RUF mock-up. RUF flammability regulations will likely have both an open flame and smoldering requirement. BFs are designed to protect against open flame, but not necessarily for smoldering.  Similar to the open flame study, the intent is to provide guidance on how to access BF smolder resistance and what attributes of the BF are critical to high smolder resistance. This task will take two years with the first year (FY14) focused on the methodology.

 


[1] Here “furniture manufacturers” refers to the producer of finished furniture. It should be recognized that such a manufacturer is likely to be assembling materials received from a wide variety of suppliers and component manufacturers.

[2] The project is currently in Phase 1. The long term vision is to reduce fire losses due to flaming residential furniture.

  • Phase 1 (FY12-FY14): Quantify contribution of flaming RUF to Nation’s fire losses, improve test methods for reduced ignition propensity cigarettes, improve understanding of smoldering transition to flaming, develop test methods for characterizing barrier fabric effectiveness, evaluate approaches for predicting burning behaviors of upholstered furniture cushion mock-ups.
  • Phase 2 (FY15-FY18): Initiate development of next-generation test for improved reduced ignition propensity cigarettes, provide measurement science to develop improved smoldering standard for upholstery fabrics, contribute to development of standard for barrier fabric effectiveness, develop approaches for incorporating the effects of geometric and construction details on the burning behavior of upholstered furniture.
  • Phase 3 (FY19-FY22): Develop an approach for predicting burning behavior of upholstered furniture based on small scale testing of components and/or composites of construction materials. Transfer the findings to the appropriate standards and testing committees and furniture manufacturing organizations.

[3] Fire Loss in the United States During 2009, by Michael J. Karter, Jr., NFPA, Quincy, MA, 02169

[4] W. M. Pitts, Quantifying the Contribution of Flaming Residential Upholstered Furniture to Fire Losses in the United States, NIST Technical Note, NIST TN

[5] J. Hall, M. Ahrens, A. Furr, and B. Pabody, “Fires with Upholstered Furniture as the Primary Item Contributing to Fire Spread,” Letter Report to William Pitts, Sept. 12, 2012.

[6] Requirements, Test Procedure and Apparatus for Testing the Flame Retardance of Resilient Filling Materials, Used in Upholstered Furniture, Technical Bulletin 117, Bureau of Home Furnishings and Thermal Insulation, North Highlands, CA, March 2000.

[7] It is anticipated that future regulation will address the flaming burning behavior of RUF in a manner similar to 16 CFR Part 1633, which has limited the maximum heat release rate of residential mattresses since 2008. CPSC has signaled an interest in this approach.

[8] NIST Special Publication 1130, Reduced Risk of Fire in Buildings and Communities: A Strategic Roadmap to Prioritize and Guide Research, April 2012.

[9] USFA National Workshop on Changing Severity of Home Fires, Maryland Fire and Rescue Institute, December 11-12, 2012.

[10] UL 2013 Furniture Flammability / Human Health Summit, Atlanta, GA, April 15-17, 2013.

[11] CPSC Upholstered Furniture Fire Safety Technology Meeting, Rockville, MD, April 25, 2013.

[12] Flashover is a rapid fire growth in which all fuels in a room become involved nearly simultaneously. It leads to untenable conditions in the room of fire origin while creating high levels of carbon monoxide and other toxic gases that are transported to other parts of a residence. The likelihood of fire spread from the room is substantially increased.

[13] The manufacturer replaced the current filter paper used as a substrate in the standard test. This new filter paper does not provide the same level of performance or reproducibility.

[14] The current SRM is a special order cigarette that may no longer be available upon request. Identifying a suitable alternative will reduce the cost of testing, reduce purchase turnaround time, and improve the reproducibility and long-term viability of the test.

[15] Environmental, health, and safety

Major Accomplishments:

Research Outcome:

  • Shonali N., et al., (2013) “Evaluating Fire Barrier Fabrics,” submitted to Fire and Materials.

Potential Research Impact:

  • Pitts W.M. (2013) “Role of Two Stage Pyrolysis in Fire Growth on Flexible Polyurethane Foam Slabs,” Fire and Materials, Fire and Materials May.

Impact of Standards and Tools:

  • Draft modification presented to ISO Technical Committee 92 Subcommittee 1 Working Group 15 on an alternate substrate data, analysis and recommendations for measuring the ignition propensity of cigarettes used for smolder ignition testing.
  • NIST guidelines used by NFPA and the US Fire Administration demonstrated that flaming RUF fires are a larger contribution to fire losses than had previously been recognized. This is expected to influence the direction of research and RUF flammability regulations.

Other:

  • Joint American University and NIST patent application for fire resistant coatings on residential furniture foam.
  • Development of reference cigarettes (SRM 1996 and 1998) used in regulation testing of mattresses (CPSC 16 CFR 1632).
Barrier fabric test - No flame penetration through barrier fabric after 6 min. Photo credit: NIST
Barrier fabric test - No flame penetration through barrier fabric after 6 min. Photo credit: NIST

Start Date:

October 1, 2011

Lead Organizational Unit:

el

Facilities/Tools Used:

Staff:

Project Leader:  Dr. William M. Pitts

Associate Project Leader: Dr. Nathan D. Marsh

 

More Information on Furniture Fire Research:

Less Fire-Prone Cigarettes

Topic: Flammability of Materials

Contact

General Information:
Dr. William M. Pitts, Project Leader
301-975-6486 Telephone

100 Bureau Drive, M/S 8665
Gaithersburg, MD 20899-8665