RR1109 - Experimental investigation of oil mist explosion hazards (Phase 1)

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

The tests compared three different fluids (kerosene, light fuel oil and hydraulic oil) sprayed through a 1 mm diameter hole at a range of pressures from 1.7 barg to 20 barg. A spark igniter was used to test for locations where the resulting jet of droplets could be ignited.

The tests showed clear differences between the fluids; kerosene could be ignited at lower pressures than would previously have been expected while hydraulic oil was not ignited in any of the tests.

Results from these tests were used to define an ignition envelope for each fluid and pressure, which was used in a second phase of tests (RR1110) to specify locations for a study of the droplets at the limit of ignitability.

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Updated 2021-04-15