VIGNETTE 7.2Muffle furnace fire

A laboratory specializing in the analysis of paint samples was asked to analyze pigmented polypropylene. The first step of the analytical protocol called for ashing the sample in a muffle furnace. The technician loaded the furnace with four crucibles containing a total of approximately 110 g of polypropylene. The temperature was set to ramp up to 900 °C. At approximately 500 °C a fire erupted from the furnace, which was quickly extinguished.

Two major contributing factors to the fire were identified. First, the technician had no experience with the analysis of polypropylene-containing samples and did not recognize that polypropylene begins to decompose at approximately 500 °C to low-molecular-weight olefins. Second, the amount of organic matter placed in the furnace in the form of the polypropylene samples was significantly more than that in the usual paint samples.

From: 7, Working with Laboratory Equipment

Cover of Prudent Practices in the Laboratory
Prudent Practices in the Laboratory: Handling and Management of Chemical Hazards: Updated Version.
National Research Council (US) Committee on Prudent Practices in the Laboratory.
Washington (DC): National Academies Press (US); 2011.
Copyright © 2011, National Academy of Sciences.

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