Oil Mist Detector
Kidde Fire Protection / Graviner Ltd
Refurbished
GRAVINER Oil Mist Detectors are engine-protection systems designed to identify a dangerous increase in crankcase oil mist. Excessive oil mist may be created by overheating bearings, friction, lubrication failure or other developing mechanical problems.
Early detection allows the engine crew to investigate the condition before it develops into severe engine damage or a possible crankcase explosion.
The GRAVINER MK5, MK6 and MK7 represent different generations of Kidde Graviner Oil Mist Detector technology. Although their operating principle is similar, the main-unit design, detector arrangement, communication system and monitoring capacity differ significantly.
| Feature | GRAVINER MK5 | GRAVINER MK6 | GRAVINER MK7 |
|---|---|---|---|
| System Generation | Legacy centralized system | Analogue addressable system | Distributed auto-addressed system |
| Detection Arrangement | Sequential sample-pipe system | Individual detector heads | Individual detector heads |
| Typical Capacity | 4–10 sampling points | Up to 64 heads across 8 engines | Up to 10 heads per control unit |
| Main Unit | Combined detector/control unit | Central main control panel | Local control unit and optional remote display |
| Alarm Method | Average, deviation and fault alarms | Average, deviation and detector alarms | Individual and average oil-mist alarms |
| Application | Main or auxiliary engines | Multi-engine installations | Modern and retrofit installations |
| Replacement Status | Legacy parts/replacement demand | Widely installed legacy system | Newer retrofit solution |
The GRAVINER MK5 is a centralized sample-pipe Oil Mist Detector. It sequentially draws an oil-mist sample from each connected crankcase compartment and measures its optical density.
Depending on configuration, the system can monitor approximately four to ten sample points. The main unit displays the sampling position, oil-mist level and system condition.
Typical MK5 indications include:
The MK5 remains installed on many older main engines and auxiliary engines. Replacement main units, internal components and retrofit solutions are still frequently required.
Related Product: GRAVINER MK5 Oil Mist Detector
The GRAVINER MK6 is an analogue addressable Oil Mist Detection System. Each detector head monitors an individual crankcase compartment and sends oil-mist data to the central MK6 main control unit.
A complete system can monitor up to approximately 64 detector heads fitted across as many as eight engines. The main control unit separates the data according to engine groups and continuously displays average oil-mist density and alarm information.
Important MK6 main-unit functions include:
Related Product: GRAVINER MK6 Oil Mist Detector Main Unit
The GRAVINER MK7 uses individually mounted detector heads with an engine-mounted control unit. This arrangement removes the need for long sampling pipes and allows continuous monitoring of each crankcase compartment.
One MK7 control unit can typically monitor up to ten detector heads. Multiple control units can be connected to an optional remote display system for larger multi-engine installations.
The MK7 system offers:
Related Product: GRAVINER MK7 Oil Mist Detector
Abnormal friction or lubrication failure can produce very high local temperatures on bearings and other moving engine parts. Lubricating oil contacting these surfaces can create a fine oil mist inside the crankcase.
The detector measures the concentration of this mist. If the oil-mist density rises above the configured average or deviation alarm level, the system activates an alarm and can provide a signal to the engine’s safety or slowdown system.
The alarm must be investigated according to the engine manufacturer’s procedures. It should never be repeatedly reset without determining the cause.
Check the supply voltage, circuit breaker, fuse, power-supply board, terminal connections and internal wiring.
Inspect the detector communication cable, cable termination, detector address and connectors. One damaged detector or cable section may affect communication with several heads.
Check the indicated detector head, connector, cable, contamination level and address. Replace the detector only after confirming compatibility.
The detector’s optical chamber may be contaminated by oil deposits. Follow the approved cleaning and test procedure. Persistent failure may require detector-head servicing or replacement.
Inspect sampling pipes, suction pressure, air passages, filters, valves and exhaust connection. Blocked or leaking pipes can prevent correct sampling.
Possible causes include contaminated detector heads, incorrect settings, oil splash, blocked drainage, damaged wiring or an actual developing engine problem. Always treat the alarm as genuine until the engine condition has been checked.
Inspect the LCD, membrane keypad, ribbon cable, display PCB and power supply. Replacement components must match the control-unit revision.
A GRAVINER MK7 maintenance schedule recommends regular recording of contamination levels and inspection based on the engine’s operating condition.
The GRAVINER MK7 can be considered for retrofit of older MK5 or MK6 installations, but it is not normally a direct plug-and-play main-unit replacement.
A retrofit assessment should consider:
Depending on stock, support may be available for:
Part numbers, photographs, software revision and existing system configuration should be provided before ordering.
A large number of vessels still operate with GRAVINER MK5 and MK6 systems. Replacing only a defective main unit, detector or PCB may allow the vessel to restore the existing OMD without changing every detector, cable and engine interface.
For this reason, tested used, refurbished and reconditioned units remain important for emergency replacement and planned maintenance.
No. Their detector technology, communication, cabling and system configuration differ. Compatibility must be checked before replacement.
A full MK6 system can monitor up to approximately 64 detector heads across eight engine groups.
One MK7 control unit can typically monitor up to ten detector heads. Multiple control units can be connected for larger systems.
The MK7 uses detector heads mounted at individual crankcase compartments, eliminating the long sequential sample pipes used by the MK5.
The unit should first be tested, and its hardware revision, software, detector compatibility, alarm settings and engine configuration must be checked.
Provide the model, part number, system generation, number of engines, number of detector heads, existing fault details and clear photographs of all nameplates.
GRAVINER MK5, MK6 and MK7 Oil Mist Detector main units provide early warning of abnormal crankcase oil mist in marine diesel engines. Used, refurbished and replacement control units, detector heads, PCBs, displays and spare parts are available subject to stock and compatibility verification.
SM MARINE SERVICE™
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Contact Information
SM MARINE SERVICE™
Samir Market, DT Road, Pahartali, beside CDA Market, Chattogram, Bangladesh
Mobile / WhatsApp / Viber: +88 01818 929292
Email: info@smmarineservice.com
Website: www.smmarineservice.com
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