Crankcase Oil Mist Detection Systems: Maintenance and Restoration | CRP MARINE

14.09.2026

Crankcase Oil Mist Detection Systems: Maintenance and Restoration

Crankcase oil mist detectors are the first line of defence against engine crankcase explosions. About calibration, integration and modernisation of legacy systems.

Crankcase Oil Mist Detection Systems: Maintenance and Restoration

Crankcase oil mist detection systems monitor the oil mist density inside the crankcase of large diesel engines and detect excessive hot spots at an early stage. The engine is thus shut down before an explosive atmosphere forms.

How Does the System Work?

Using an optical detection method, the ratio of condensed mist in the sample drawn from the crankcase is measured. When the alarm level is reached, the engine protection circuit initiates load reduction or shutdown.

Maintenance Requirements

  • Periodic cleaning of detector lenses and optical surfaces.
  • Calibration and verification of alarm set points.
  • Leak checks on vacuum/sampling lines.
  • Communication with engine control systems and alarm tests.

Modernisation of Legacy Systems

On long-lived vessels, older generation detectors are replaced with modern self-testing systems as spares and service support decrease. Restoration works are documented in line with engine maker requirements and submitted for class approval.

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