Low Heat Release Upholstered Furniture

Summary

To reduce the flammability of residential upholstered furniture (RUF), the fire safety community has developed test methods and mitigation strategies based on the ignition source type – smoldering or open-flame.  Recent analysis of fire losses indicates that RUF fires are 12 times as deadly as residential fires in general and a majority of the RUF fire causalities occur when the RUF is flaming, regardless of the ignition source type.  Therefore, this project will conduct research aimed at significantly enabling low heat release upholstered furniture (L-RUF), i.e., furniture with very low heat release and peak heat release rate.  Due to concerns about the use of fire retardants in RUF, this project will also conduct research to identify and support the development of non-fire retardant technologies that enable L-RUF. 

Since the fire community and the existing standards and regulations still view RUF flammability in terms of ignition type (primarily smoldering ignition), this project will also continue to guide decreases in RUF smoldering ignition losses by supporting the use of NIST SRM cigarettes in standard fire testing and supporting the development of new or improved smoldering test standards. 

Description

Barrier fabric test - No flame penetration through barrier fabric after 6 min. Photo credit: NIST

PROJECT OBJECTIVE:
The objective is to reduce the fire hazard of residential upholstered furniture by providing 1) a methodology and guidance on non-fire-retardant mitigation strategies that will result in L-RUF, 2) robust standard reference cigarettes for smoldering ignition testing and the manufacturing of reduced ignition propensity cigarettes, 3) a standard bench-scale methodology for predicting the smoldering hazard of RUF.

WHAT IS THE TECHNICAL IDEA?
The new technical idea is to conduct research that results in low heat release and peak heat release rate RUF (L-RUF) and provides an understanding of how to achieve this without the need for conventional fire retardants (FR).    Reducing the fire hazard of residential upholstered furniture (RUF) is the highest priority for residential fire research now and, if not resolved, will remain the highest priority in the future.[1]  RUF flammability is a priority because it is deadly.  Even though RUF is only involved in 2 % of the residential fires, it accounts for 25 % of all residential fire deaths and property losses. 

Typically, RUF fires are reported, discussed, and technologies to reduce are applied based on the ignition source type and that RUF is the first item ignited.  The two most common RUF ignition source types are open flame (e.g.; candle) and smoldering (e.g.; cigarette).  Smoldering ignition RUF fires are viewed as deadlier because, based on NFPA statistics[2], about 65 % of these RUF fires deaths result when there is a smoldering ignition source, as compared to 30 % when there is an open flame ignition source (flaming RUF).  However, subsequent independent analyses by NFPA and NIST[3] suggest a different understanding of these RUF fire deaths. 

NFPA and NIST analyses indicate flaming RUF is the critical factor in RUF fire deaths.  These analyses indicate a significant number of fire deaths resulted after the smoldering in the RUF transitioned to flaming combustion (flaming RUF).  These analyses also indicate there are additional RUF fire deaths not captured in the “first item ignited” statistics discussed above.  These additional fire deaths occur when RUF isn’t the first item ignited but considered to be a main factor in the fire losses.  In these cases, RUF is always considered flaming.  These important conclusions combined with the open flame ignition RUF statistics indicate a majority of the RUF fire deaths and other losses occur when there is flaming RUF.  This role of flaming RUF is a critical finding and requires a paradigm shift in RUF fire research and regulations toward limiting the fire growth rate and size (lower heat release) of flaming RUF and away from reducing RUF fire hazard by increasing its resistance against ignition sources.

There is a broad, but incorrect, perception that reducing RUF heat release rate requires the use of FR.  However, some FR previously used in RUF were reported as having deleterious effects on people and the environment.  There are also reports indicating that such compounds only resulted in marginal reductions in RUF flammability.  As a result, there has been a strong and effective public backlash aimed at preventing the use of any FR chemicals in RUF.  Until nonFR technologies are identified or developed, there doesn’t appear to be a viable approach to produce L-RUF, and, therefore reduces fire deaths from flaming RUF.

WHAT IS THE RESEARCH PLAN?
The primary focus of this project is to provide accurate fire performance metrics that enable reduction of the burning hazard of RUF without using conventional FR (Task 1: Flaming).  This project will also include two smaller tasks that will include our ongoing activities to reduce the frequency of smoldering ignitions (Task 2. Standard Reference Materials and Task 3. Smoldering)

Task 1. Flaming: This research will provide the test methods for RUF items and their components that are needed for developing low heat release and peak heat release rate (L-HRR, < 200 kW) residential upholstered furniture (RUF) without the use of harmful chemical fire retardants (FR).  This will be achieved by developing a bench-scale tool (the Cube) for the Cone Calorimeter to predict the ability of non-fire-retardant barrier technologies (nonFR-BT) to produce L-HRR real-scale furniture.  Based on our premise that to be effective without using FR requires the BT to limit fire growth through physical mitigation (reductions in heat and mass transfer), the Cube will be modified to identify and quantify these physical mitigation processes.  Using this mechanistic understanding a pyrolysis model will be developed and validated with the Cube results to predict the ability of nonFR-BT to delivery L-HRR RUF.  In order to execute this task, the research will conduct Cube and modified-Cube bench-scale tests and full-scale furniture tests using a range of combinations of nonFR-BT, filler material (foam and polyester), and upholstery fabrics.

Task 2. Standard Reference Materials: This research will provide new batches of and community support for NIST Standard Reference Material (SRM) cigarettes: SRM 1196 and SRM 1082.  SRM 1196 is a standard cigarette used for regulatory ignition testing for mattresses[4] and used in standardized testing for residential upholstered furniture[5].  SRM 1082 is a standard low ignition propensity cigarette that cigarette manufacturers, testing laboratories and regulatory agencies use make accurate measurements to determine if potential cigarette designs and commercially sold brands meet the fire safety regulations.  This task will deliver a new 10 year supply of SRM 1196 (SRM 1196a) and develop a plan for procuring a new 10 year supply of SRM 1082 (SRM 1082a).  Currently, NIST has a 6 year supply of SRM 1082 and limited storage capacity, so the SRM 1082a plan won’t be executed until FY21-22.

Task 3. Smoldering: This research will be the basis for a new smoldering ignition testing standard that is aligned with the smoldering behavior measured in full-scale furniture.  Our previous project on RUF explained the mechanism of smoldering as a combination of heat transfer from the cigarette to and oxygen flow from outside and through the substrate to the smoldering front.  That project also showed modest changes to the standardized methods yielded a stronger alignment between the bench-scale and full-scale smoldering behavior.  During this new project, the focus will be on tech transfer.  There will be 2-3 publications on the mechanism, standard approach to full-scale testing, and modification to the standard bench-scale approach.  In addition, NIST has agreed to participate in a NFPA 260 task group assigned with reviewing information (such as NIST research) and preparing a draft revision of this standard for consideration by the NFPA Committee on Fire Tests.

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[1] Davis, R. D., et al. (2018). NIST Special Publication 1220 Workshop Report: Research Roadmap for Reducing the Fire Hazard of Materials in the Future. National Institute of Standards and Technology Special Publications. Gaithersburg, MD. https://www.nist.gov/publications/workshop-report-research-roadmap-reducing-fire-hazard-materials-future     

[2] Ahrens, M., Home Fires that Began with Upholstered Furniture,” NFPA, February 2017.

[3] Thomas, D. S., and D. T. Butry, Identifying Residential Fires Involving Upholstered Furniture within the National Fire Incident Reporting System, NIST Technical Note 1845, National Institute of Standards and Technology, Gaithersburg, MD, 2016.

[4] Consumer Products Safety Commission, 16 CFR 1632 Standard for the Flammability of Mattresses and Mattresses Pads. https://www.cpsc.gov/s3fs-public/pdfs/blk_media_testmatt.pdf  

[5] National Fire Protection Association 260 Standard Methods of Tests and Classification System for Cigarette Ignition Resistance of Components of Upholstered Furniture. Published 2013. https://www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards/detail?code=260.