Assessment of Factors Affecting Fire Performance of Mattresses: a Review
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NIST Technical Note 1740 Assessment of Factors Affecting Fire Performance of Mattresses: A Review Shonali Nazaré Rick. Davis March 2012 i NIST Technical Note 1740 Assessment of Factors Affecting Fire Performance of Mattress: A Review Shonali Nazaré Rick D. Davis Fire Research Division Engineering Laboratory National Institute of Standards and Technology March 2012 U.S. Department of Commerce Gary Locke, Secretary National Institute of Standards and Technology Patrick D. Gallagher, Under Secretary of Commerce for Standards and Technology and Director ii Certain commercial entities, equipment, or materials may be identified in this document in order to describe an experimental procedure or concept adequately. Such identification is not intended to imply recommendation or endorsement by the National Institute of Standards and Technology, nor is it intended to imply that the entities, materials, or equipment are necessarily the best available for the purpose. National Institute of Standards and Technology Technical Note Natl. Inst. Stand. Techn. Techn. Report XXX, 53 pages (March 2012) CODEN: NTNUE2 iii Abstract An in-depth analysis of U.S. residential fire statistics shows that although the total number of fires and deaths due to mattress fires has dropped as a result of several regulatory approaches including reduced risk of ignition through reduced ignition propensity cigarettes, reducing fire spread through residential sprinklers, and reducing the inherent fire hazard of fuel sources through lower heat release (HR) mattresses, the number of deaths per 1000 mattress/bedding fires has increased over past 3 decades. To address the increasing number of deaths due to mattress fires, the open flame mattress flammability regulation (16 CFR 1633) was recently introduced in the U.S. The 16 CFR 1633 prescribes performance standards rather than design standards; this allows manufacturers the flexibility to meet the needs of the consumer without sacrificing fire safety. This flammability regulation for residential mattress has generated much interest in understanding the burning behavior of mattresses as well as in developing new materials for mattress construction. To comply with this regulation, it is essential to understand mattress construction, fire performance testing, factors affecting mattress flammability, and compliance solutions. This report reviews the impact of current mattress flammability standards, examines factors affecting mattress flammability, and reviews full-scale and bench-scale test methods that are being developed for mattresses. The construction type, geometry, and size of a mattress are major factors in determining the fire threat of a mattress. The size effect is only significant for standard mattresses without any FR (flame retardant) modification. The soft materials used in the mattress set, including cushioning materials, fire blocking materials, and tickings, act both individually and collectively to affect the fire performance. The performance of fire barrier materials designed to protect the inner cushioning material from heat and flame is largely dependent on the choice of cushioning material and ticking. When used with an incompatible combination of filling material and ticking, a fire barrier may fail to protect thermal degradation and subsequent burning of filling material. Some of the challenges in designing mattresses have been identified and reported here. Keywords Soft furnishings, mattresses; flammability standards; testing; heat release rate; ticking; barrier fabric; bedclothes. iv This page left intentionally blank. v Contents Abstract ......................................................................................................................................... iv List of Tables ............................................................................................................................... vii List of Figures ............................................................................................................................. viii List of Acronyms ........................................................................................................................... 9 1. Introduction ............................................................................................................................. 11 2. Mattress Flammability Regulations and their Impact on Fire Statistics ........................... 12 3. Mattress Construction and Component Materials .............................................................. 14 3.1. Frame and foundation ........................................................................................................ 14 3.2. Mattress support system ..................................................................................................... 15 3.3. Cushioning and comfort layer ............................................................................................ 15 3.4. Fire blocking materials ...................................................................................................... 15 3.5. Ticking ............................................................................................................................... 16 4. Mattress Flammability Testing .............................................................................................. 17 4.1. Full-scale testing ................................................................................................................ 17 4.2. Bench-scale testing ............................................................................................................ 18 5. Factors Influencing Fire Performance of Mattresses .......................................................... 19 5.1. Mattress dimensions........................................................................................................... 19 Mismatch between foundation and frame ............................................................................. 19 Impact of mattress size .......................................................................................................... 19 5.2. Mattress Construction ........................................................................................................ 20 Interaction of the mattress and foundation ........................................................................... 20 Innerspring vs. solid core constructions ............................................................................... 21 5.3. Ticking ............................................................................................................................... 21 5.4. Fire barrier materials .......................................................................................................... 23 5.5. Bedclothes .......................................................................................................................... 24 6. Conclusions .............................................................................................................................. 25 7. References ................................................................................................................................ 52 vi List of Tables Table 1. Standards and test methods for mattress and beddings................................................... 43 Table 2. Scope of variations in mattress designs .......................................................................... 46 Table 3. Heat release test data for various mattress constructions [29] ........................................ 47 Table 4. Heat release data for residential mattresses [32]. ........................................................... 48 Table 5. Classification of ticking according to 1632.6 of 16 CFR 1632 [1]................................. 49 Table 6. Heat release test data for mattresses with different tickings [33]. .................................. 50 Table 7. Details of mattress construction and components [29]. .................................................. 50 Table 8. Description of mattress pads and fiberfill [19]. .............................................................. 51 Table 9. Description of FR modified bedding assemblies and FR bedclothes [19]. .................... 51 vii List of Figures Figure 1. Mattress-bedding related US residential fire losses from 1980 to 2006, delineated by ignition source. Number of (a) fires, (b) civilian injuries, and (c) civilian fatalities [13]. .......... 28 Figure 2. 1980 to 2006 US residential fire losses according to ignition source. Number of (a) fires, (b) civilian injuries, and (c) civilian fatalities [13]. ............................................................. 31 Figure 3. Mattress/bedding-related US residential fire losses from 1980 to 2006; civilian fatalities per 1000 mattress/bedding fires (for all ignition sources) [13]. ..................................... 32 Figure 4. Schematic of a typical residential mattress and foundation set: (a) innerspring and (b) solid foam [38]. ............................................................................................................................. 33 Figure 5. Impact of bed sizes on fire performance of (i) M-I Standard non-FR mattress, (ii) M-II Standard non-FR mattress with fire barrier and (iii) M-III FR mattress with FR ticking [18]. .... 34 Figure 6. Impact of foundation on fire performance of mattresses [29]. ...................................... 35 Figure 7. Impact of mattress construction on peak heat release