RR1110 - Experimental investigation of oil mist explosion hazards (Phase 2)

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, describes the second phase of experimental tests to examine the ignition of mists produced by small leaks of pressurised, combustible fluids.

The size, concentration and movement of droplets were examined. The results differed significantly from those predicted by simple mist formation theories. This appeared to be the result of fundamental fluid behaviour. For all the test conditions, the droplets in the core of the spray were larger and had higher velocities than those closer to the edge. With viscous fluids the core included long ligaments, though these were difficult to measure.

These results show that simple spray models are not always appropriate for assessing the ignitability of oil mists from pressurised leaks.

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Updated 2021-04-15