Modeling full-scale fire test behaviour of polyurethane foams using cone calorimeter data

Abstract

Flexible polyurethane foam (PUF) is a very versatile material ever created. The material is used for various applications and consumer end-use products such as upholstered furniture and mattresses. The increased use of these polymeric materials causes fire safety concerns. This has led to the development of various regulations and flammability test standards aimed at addressing the hazards associated with polyurethane foam fires. Several fire protection engineering correlations and thermal models have also been developed for the simulation of fire growth behaviour of polyurethane foams. Thus, the overall objective of this research project is to investigate the laboratory test behaviour of this material and then use finer modeling techniques to predict the heat release rate of the specimens, based on information obtained from cone calorimeter tests.

Full-scale fire tests of 10 cm thick polyurethane foams of different sizes were conducted using center and edge-ignition locations. Flame spread and heat release rates were compared. For specimens of the same size, center-ignition tests produced flame areas and peak heat release rates which were respectively 10 and 20% larger compared to edge-ignition tests. Average flame spread rates for horizontal and vertical spread were determined, and results showed excellent agreement with literature. Cone calorimeter tests of the specimens were performed using steel edge frame and open durarock board. Results indicate that different test arrangements and heat sources have significant effects on the fire behaviour of the specimens.

Predictions using the integral convolution model and other fire protection engineering correlations were compared with the full-scale tests results. Results show that the model was more efficient in predicting the heat release rates for edge-ignition tests than the center-ignition tests. The model also was more successful in predicting the heat release rates during the early part of the growth phase than during the later stages of the fire. The predicted and measured peak heat release rates and total heat release were within 10-15% of one another. Flame spread and t-squared fire models also gave satisfactory predictions of the full-scale fire behaviour of the specimens.