Oil mist

Oil mist refers to oil droplets suspended in the air in the size range 1~10 μm.

Formation of Oil Mist

Oil mist may form when high pressure fuel oil, lubricating oil, hydraulic oil, or other oil is sprayed through a narrow crack, or when leaked oil connects with a high temperature surface, vaporizes, and comes in contact with low air temperature.

This happens while the fluids interact with the moving parts during machining.[1]

Smaller oil droplets than oil mist are difficult to generate under normal circumstances.

Bigger oil droplets than oil mist remain in spray form; this has the advantage of a higher ignition temperature. It sinks easily, reducing fire hazard. Oil mist inside the crankcase can cause a bigger problem.

Risks

When the concentration of oil mist increases and reaches the lower explosion limit (LEL; 50 mg/ℓ, as defined by the IACS), explosion may occur when the mist contacts surfaces of over 200 °C (392 °F) or a spark.

The International Association of Classification Societies (IACS) mandates that all ships with a cylinder diameter greater than 300mm or engine power over 2,250 kW must be equipped with either bearing temperature detectors or oil mist detectors.[2]

In regards to occupational exposures, the Occupational Safety and Health Administration and the National Institute for Occupational Safety and Health have set occupational exposure limits at 5 ppm over an eight-hour time-weighted average, with a short-term exposure limit at 10 ppm.[3]

References
  1. "What is oil mist". Retrieved April 2, 2014.
  2. "A Current List of Cruise Ship Incidents - Ship Fires". Shipdetective.com. Retrieved 2013-09-06.
  3. CDC - NIOSH Pocket Guide to Chemical hazards
  4. "Mexico Pipeline Explosion Kills 28". Retrieved April 2, 2014.

1 International Maritime Organization (IMO)

2 International Association of Classification Societies Ltd unified requirements concerning MACHINERY INSTALLATIONS

3 Oil Companies International Marine Forum Ship Inspection Report (SIRE) Programme/ Vessel Inspection Questionnaires for Oil Tankers, Combination Carriers, Shuttle Tankers, Chemical Tankers and Gas Carriers

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