RR1108 - Liquid classification for flammable mists

Many types of industrial equipment can potentially produce an explosive oil mist if a fault develops. However, information on the conditions in which a mist can be ignited and continue to burn is limited. To help address this, HSE and 14 industry sponsors co-funded a Joint Industry Project (JIP) on oil mist formation and ignition.

This report, produced for the JIP, addresses the contribution the fluid within a pressurised system makes to the risk of an ignitable mist forming if a leak develops.

Fluids were put into three groups, based on their flashpoint and ease of atomization: "volatile fuels" include fuels and solvents which have a low flashpoint and atomize easily; "lubricants" include many actual lubricants and also heat transfer fluids and other oils with a relatively high flashpoint and poor atomization; "fuel oils" which have a low flashpoint but poor atomization.

When heated, "fuel oils" should show similar behaviour to "volatile fuels".

This work was used to select a representative fluid from each group for use in experimental tests.

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Updated 2021-04-15