A test method for smolder resistance of upholstered furniture

The purpose of this research was to find a test method and a fabric classification procedure which would reliably indicate whether fabrics could perform in a fire safe manner when tested on a modification of the National Bureau of Standards (NBS) test assembly. The NBS upholstered furniture fabric test apparatus was modified to allow the use of polyester fiberfill as a substratum. A test method and classification procedure for upholstery fabric was devised to specify combinations of fabric and substrata that are fire safe. This fabric/substrata flammability test method and procedure defined conditions under which upholstery fabric could perform in a fire safe manner.

Thirteen upholstery fabrics were selected as representative of currently available fabrics. The fabrics contained natural fiber, manmade fiber, and a wide range of blends. These fabrics were tested over polyester fiberfill. The test apparatus used was a modification of the NBS fabric test apparatus for testing upholstery fabric.

The fabrics were tested and classified by CPSC, Upholstered Furniture Action Council, and modified test methods and procedures. Char lengths were determined to be the most reliable method for classifying flammability of upholstered fabric. A t-test was used to determine differences in char lengths produced by fabrics tested on the NBS test apparatus and the modified test apparatus. An analysis of variance was used to determine selected influences of fabric construction on the char lengths produced.

Using the modified test method and classification procedure, some 100 percent cotton fabrics can be used in furniture construction provided the specified substratum is also used. Some fabrics were considered to be questionably safe when tested on either the NBS or the modified test apparatus. Other fabrics performed better on the modified test when compared to the NBS test results. Fabric classification by the UFAC method was not necessarily indicative of performance in flammability tests.

The modified test procedure couples the practicality of using substrata materials that are common to the industry while still retaining some of the severity of the CPSC's staff proposal for testing flammability of upholstery fabrics. This modified test indicates that only the most smolder resistant combinations of fabrics and strata should be used for furniture construction.