ABC of Safety in the Biological Sciences




These are liquids or mixtures of liquids containing solids in suspension which have a flashpoint not greater than 61oC. The flashpoint is the lowest temperature at which the liquid gives off sufficient vapour to be ignited at the surface. Flammable liquids do not burn but the mixture of vapour with air does.

At room temperatures most flammable liquids will vaporise sufficiently to cause burnable mixtures with the atmosphere. These vapours are usually invisible and often have no smell. They are invariably heavier than air and if ventilation is inadequate the vapours will settle in low areas. The vapour can spread over a considerable distance from the liquid (often many metres) and if an ignition source is encountered the fire produced will flash back along the vapour trail.82 83

Material safety data sheets will contain information on the flashpoint of flammable liquids.

Precautions to be followed include:

  • use a less hazardous substance if possible
  • avoid or eliminate all ignition sources
  • use good ventilation wherever flammable liquids are handled
  • store flammable liquids in a well-ventilated area
  • connect large metal drums containing flammable liquids to earth to eliminate static electricity
  • install pressure release valves in opened, large drums
  • dispense from only one container at a time
  • ensure that all containers are adequately labelled
  • dispose of waste safely
  • wear protective clothing to avoid skin and eye contact and inhalation of the vapours
  • handle 'empty' flammable liquid containers with care


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