Memo 9/08: Laboratory explosions

Memo M8/07 notified departments of the explosion of a glass Winchester in an unoccupied laboratory and warned of the dangers that could arise from inappropriate mixing of waste chemicals.

In the last few weeks there have been two similar incidents involving Winchesters of waste chemicals. One involved mixed waste of unknown composition; the other involved a mixture of chloroform and acetone, which is known to react exothermically in the presence of trace amounts of base. As in the incident described in Memo M8/07, a risk assessment would have identified these waste collection bottles as a source of danger.

It is fortunate that in all three cases described the bottles burst while there was no-one present. A similar incident at the City of Bristol College resulted in a lecturer being seriously injured by glass shrapnel and concentrated nitric acid[1]. The college was prosecuted, found guilty and fined £14000 with £18000 costs. The injured lecturer, supported by the University and College Union, is making a civil claim for compensation.

Glass Winchesters are not intended to withstand excess pressure, which may be easily generated by an unexpected chemical reaction or by vapour expansion in a tightly sealed bottle (e.g. caused by storage in a warm atmosphere, in direct sunlight, or the use of a bottle with an unvented cap). Generally speaking, wastes should not be mixed with wastes of another type and chemically incompatible materials must never be mixed. Information on incompatibility can be found in Materials Safety Data Sheets and on Physical and Theoretical Chemistry’s web pages at

Departments should review their waste collection and disposal methods, assess the risks involved, and ensure that no harm will arise from their chosen method.