FIRE PERFORMANCE OF POLYURETHANE FOAM: CALIFORNIA TECHNICAL BULLETIN 117 AND BRITISH STANDARD BS5852

摘要

The ignitability and fire performance of polyurethane foam have long been shown to be veryrnpoor, unless the foam was treated with fire retardant additives. The state of California has beenrnrequiring since 1975 that all polyurethane foam used in upholstered furniture comply with a smallrnopen flame standard known as CA TB 117 [1]. The United Kingdom has required, since 1988, thatrnpolyurethane foam comply with a severe small open flame standard, BS5852 [2], and was joined byrnIreland later.rnThis study looks at some work regarding the effectiveness of these standards in terms of improvingrnthe fire safety of polyurethane foam and, especially, that of upholstered furniture containing suchrnfoam.rnA recent study conducted for the US National Institute of Justice (NIJ, [3]) investigated the firernperformance of upholstered furniture. This study involved full scale fire tests on existing furniture andrnon upholstered furniture mockups constructed with one of four foams and one of two fabrics, andrnsmall scale tests on the foam and fabric combinations. One of the foams used complied with BS5852rncrib 5, one complied with CA TB 117, and the others were standard non fire retarded foams ofrndifferent densities. One fabric complied with the NFPA 701 [4] fabric flammability test and one didrnnot.rnEarlier work on a full scale study of identical residential US sofas differing purely in the nature of thernfoam showed that the sofa with CA TB 117 foam required the use of a more severe ignition sourcernthan the one with non FR foam. Moreover, even with the more severe ignition source, the sofa withrnCA TB 117 foam gave occupants an extra minute to escape. However, once the sofa ignited,rneventually both sofas caused a self-propagating fire and reached flashover conditions. In the samernstudy, a residential UK sofa, with foam complying with BS5852 crib 5, did not ignite. This result isrnrepresentative of similar types of results obtained in various proprietary full scale studies comparingrnthe three types of foams.rnIn the NIJ study it was found that upholstered furniture mock-ups with CA TB 117 foam (even usingrnstandard non FR foam) provided significantly longer times to ignition or delays before a fire becamernsignificant. For example with an ignition source at the back the delay was some 7 minutes. Moreover,rnthe peak heat release rate was significantly lower for the CA TB 17 foam. When CA TB 117 foamrnwas combined with an NFPA 701 fabric, the upholstered furniture mock-ups resisted ignition evenrnwith a fairly significant flaming source on the seat. For comparison purposes, mock-ups with foamrncomplying with BS5852 crib 5 were able to resist ignition in virtually all cases, even with non FRrnfabrics.rnThe CA TB 117 foams were unable to resist ignition from most of the ignition sources and, oncernignition occurred, large fires resulted, as opposed to the experience with BS5852 crib 5 foams.rnHowever, this work shows, once more, that CA TB 117 foams provide a level of ignition protection that is significant (albeit not enough for adequate fire safety) and that the elimination of such arnsafeguard would result in an important lowering of fire safety.