Three research students have died in an explosion in the Environmental Engineering Laboratory at Beijing Jiaotong University. The incident occurred at about 9.30 am local time on Wednesday 26 December 2018, while the students were carrying out an experiment as part of a research project into sewage treatment. The building where the laboratory was housed was evacuated while firefighters tackled a blaze in the laboratory, but there were no further casualties associated with the event.
The scene of a fire at the Environmental Engineering Laboratory at Beijing Jiaotong University on 26 December 2018. Wevideo/South China Morning Post.
The cause of the incident is still being investigated, but there are a number of ways in which experiments into sewage treatment could result in an explosion. The most obvious of these is a build up of methane (CH4) in a pressurised container. Methane is formed by the decay of organic material, and is a flammable gas widely used as a fuel, and build-ups of the gas in enclosed spaces can lead to explosions, but sewage does not produce large amounts of methane, and it is unlikely that enough sewage samples would be stored in a lab to produce sufficient methane to cause a deadly explosion; a sewage-related methane explosion in a lab is likely to have been messy and unpleasant, but not fatal.
A more likely explanation would be an explosion fuelled by solvents or gasses stored in the laboratory. Samples from sewage sludge, or other environmental substances, cannot simply be analysed without preparation in the way often depicted in TV programs, but require some preparation first. Typically this will involve treating the sample in a solvent such as pentane (C₅H₁₂) prior to analysis in an instrument such as a gas chromatograph mass spectrometer. Pentane is extremely combustible (as are any similar solvents that could be used as a substitute), and even fairly low quantities will release a great deal of energy if ignited, which means that a great deal of care when it is being used, and steps should always be taken to minimise the amount kept within a laboratory at any given time.
In addition, gas chromatographs (and similar ), as the name suggests, require the use of pressurised gasses, and whilst these are typically inert gasses such as helium or nitrogen (sometimes more hazardous gasses such as hydrogen are used), gas cylinders are also potentially dangerous, and can explode if damaged (more often than not, any damage that occurs will be to the release valve at the top of the cylinder, causing the cylinder to 'torpedo', highly dangerous within an enclosed space).
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