Oil Mist

The earliest recorded oil mist fires and crankcase explosions dates back to the genesis of diesel engine development, when Rudolf Diesel himself mentioned the problem in his early writings.

However, it was in 1947, following the MV Reina Del Pacifico disaster in which 28 people died, that the dangers of oil mist gained greater attention, though it wasn’t until the early 1960s that the first crankcase oil mist detector was introduced.

The need to monitor the accumulation of oil mist in an engine’s crankcase and machinery spaces was further recognized when classification reports estimated that between 1990 and 2001 some 700 engines were written off as a consequence of oil mist-based crankcase fires or explosions. P&I Clubs went further claiming that up to 65% of all ship fires were the result of pressurized fuel and lubricating/hydraulic oil droplets collecting in the atmosphere of machinery spaces.

This fine, highly flammable mist of between 1 and 10µm is produced at surface temperatures of between 200°C and 600°C, while droplets greater than 50µm are typically produced from pinhole leaks in a pressure line.

In an open machinery space, oil mist or spray of any droplet size must be treated as a potential fire risk and appropriate detection systems should be in place to safeguard ships’ crew and equipment before it becomes a MAIB incident.

“Escaping oil mist to the atmosphere is the cause of a significant percentage of fires and deaths at sea.”

Above Example of oil mist in the atmosphere
Above Example of oil mist in the atmosphere dispersing over 1 meter in a controlled environment.


Typical sources of atmospheric Oil Mist includes:

  • Leaking injectors
  • Fractured flexible hoses
  • Loose or incorrectly fitted pipe fittings
  • Broken welds
  • Poor maintenance of machinery and pipe work

Typical sources of ignition includes:

  • Exhaust pipes
  • Turbochargers
  • Non-flameproof motors
  • Electrical contacts
  • Static electricity
  • Faulty wiring

Further information about oil mist detection is available from these QMI White Papers

Oil mist and machinery space fires

New regulations for atmospheric oil mist detection

Oil mist detection in engine rooms

Oil mist detection as an aid to monitoring engine condition

IMO Code of Practice for oil mist detection