Influence of oxygen depletion on the radiative properties of PMMA flames

This work presents data on the flame properties of polymethyl methacrylate (PMMA) pool fires burning in nitrogen-diluted atmospheres. The measurements were performed on a 30-cm diameter pool fire equipped with a fuel level control device, with which it was possible to maintain constant mass loss rate for the duration of the test. The tests were performed in a water-cooled enclosure. The measured quantities were: Schmidt temperature, emittance, radiative power per unit height along the flame, mass loss rate and flame shape. Values for these properties were measured at four different ambient oxygen concentrations. The results were very repeatable. It was found that mass loss rate, flame emittance, and total radiation all decreased significantly with decreasing ambient oxygen concentration, while the Schmidt flame temperature was much less sensitive. The results may be interpreted as indicating that a drop in the ambient oxygen concentration influences the fire primarily through a decrease in soot concentration. The total heat release per unit flame volume was found to be weakly dependent on oxygen concentration.