Burning of Electrical Household Appliances: An Experimental Study

Burning characteristics of electrical household appliances of four different types, TV sets, washing machines, dishwashers and refrigerator-freezers, have been studied experimentally. Results obtained comprise rate of heat release, mass loss and generation of smoke and some chemical substances as well as the quantities derived from these data such as the effective heat of combustion. The experiments are comprehensively documented by written records of events and photographs. High intensities of burning were detected. The highest rates of heat release (RHR), up to 2000 kW, were found for refrigerator-freezers. The peak RHR values for the other apparatuses were: dishwashers 350-750 kW, washing machines 300-450 kW and TVs 250-300 kW. Generally, the development of the burning of the apparatuses towards full burning has two phases. The first phase involves low-RHR incipient burning and during the second phase RHR grows rapidly towards the peak values. TV set fires develop rapidly: the first phase lasts ca. 1,5-3 minutes and, after it, the peak RHR value may be reached within 1-1,5 minutes from the initiation of the rapid RHR growth. For washing machines the period of incipient burning was rather long, 10-20 minutes depending on the way the apparatus was ignited (ignition in the motor space or at the control panel). For the dishwashers the delay was 5-10 minutes. A similar delay was found also in three refrigerator-freezer experiments. In one refrigerator-freezer experiment, the delay time was clearly shorter, only 2-3 minutes. A computational analysis of the development of room fires originating from ignited electrical household appliances was conducted to study the significance of the measured burning characteristics. The RHR of refrigerator-freezers is so high that fires originating from these apparatuses probably lead to flashover. In the case of dishwasher fires, the likelihood of flashover is considerable. The probability of flashover TV set fires in relatively large spaces (such as living rooms) depends mainly on the probability of ignition of other items in the room. In small rooms, e.g., children's bedrooms, the TV fires are considerably more dangerous than in larger rooms. In the case of washing machine fires, the development of the fire is in practice usually governed by the availability of oxygen since the rooms with washing machines mainly have closed openings. Smoke production was high especially for TV sets. Thus, smoke damages are likely to be considerable in fires involving electrical household appliances.