Performance of HS-HR flexible foams in small open-flame combustibility tests

The development of small open-flame tests for measuring or predicting the combustibility characteristics of flexible polyurethane foams continues to be a subject of broad interest and active research. Notable recent activities in the residential furniture area include: (1) efforts by the California Bureau of Home Furnishings and Thermal Insulation to improve CAL TB 117; (2) work towards a national standard by the Consumer Products Safety Commission; and (3) the development and/or evaluation of test methods by the API, PFA, ASTM, and AFMA. In this paper, we report the results of a systematic study in which several high support, high resilience (HS-HR) flexible polyurethane foams were tested by various small-scale open-flame combustibility tests. These tests include the current CAL TB 117 A Part 1, the February, 2002 draft proposal of the new CAL 117 (Section 3 Options A and B, and Section 5 using a fabric compliant with the current CAL TB 117 E), and a cone calorimeter test. The HS-HR foam variables included level of flame retardant, density, SAN versus PHD solids type and the level of solids. Various performance criteria in the test methods were modeled against each other and against the foam variables. These results highlight the difficulties in correlating performance between different small open-flame tests and provide insights into the factors contributing to passage or failure in these tests. New technology for improving the combustibility performance of HS-HR foams in these tests will be discussed.