MDE Unit 6 Q2

An engine crankcase oil mist detector is a safety device that continuously monitors the concentration of oil mist within the engine crankcase.  

1. Oil Mist Detector | DAIHATSU DIESEL

How it works:

• Oil mist detection: The detector employs a sensor, often based on light scattering technology, to measure the amount of oil mist present in the crankcase atmosphere.   1. What is engine Oil Mist Detector (OMD) and what to do in case of an oil mist alarm chiefengineerlog.com
• Alarm activation: When the oil mist concentration exceeds a predetermined threshold, the detector triggers an alarm, alerting the operator to a potential issue.   1. Oil Mist Detector & Monitoring System｜MEIYO ELECTRIC Co.,Ltd. www.meiyoelc.co.jp

Purpose:

• Early warning: Detects engine problems at an early stage, such as wear or seal failures.
• Preventing explosions: Oil mist can create a flammable mixture in the crankcase. By detecting high oil mist levels, the detector helps prevent explosions.
• Protecting engine and personnel: Early detection allows for corrective actions to be taken, preventing further damage to the engine and protecting personnel.

By continuously monitoring the crankcase environment, oil mist detectors provide an essential safety measure for diesel engines.  

1. What is engine Oil Mist Detector (OMD) and what to do in case of an oil mist alarm

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engine crankcase oil mist detector

Crankcase oil mist detectors employ various technologies to monitor the engine’s condition. Here are some common types:

1. Light Scattering Detectors:

• Principle: These detectors use a light source and a photodetector to measure the amount of light scattered by oil droplets in the air.
• Sensitivity: Highly sensitive to even small amounts of oil mist.
• Common application: Widely used in industrial and marine applications.

2. Optical Sensors:

• Principle: Similar to light scattering detectors, but often use laser technology for more precise measurements.
• Sensitivity: Typically offer higher sensitivity and accuracy compared to light scattering detectors.
• Applications: Used in critical applications where early detection is essential.

3. Acoustic Sensors:

• Principle: Detects changes in sound frequency caused by the presence of oil droplets.
• Sensitivity: Less sensitive compared to light-based detectors.
• Applications: Primarily used in conjunction with other detection methods.

4. Gravimetric Detectors:

• Principle: Collects oil droplets on a filter and measures the weight increase.
• Sensitivity: Less sensitive for real-time monitoring but useful for long-term trend analysis.
• Applications: Used for periodic checks and maintenance purposes.

The choice of detector depends on factors such as sensitivity requirements, cost, and the specific application. It’s often beneficial to use multiple detection methods for comprehensive engine monitoring.

The activation of an engine crankcase oil mist detector is a serious event indicating potential engine damage. The following steps should be taken immediately:

Immediate Actions:

1. Stop the Engine: Gradually reduce engine speed and bring it to a safe stop. Avoid sudden shutdowns to prevent hydraulic lock.
2. Inform the Bridge: Notify the bridge of the engine shutdown and the reason.
3. Activate Alarm: Sound the general alarm to alert other crew members.
4. Isolate the Engine: Close the necessary valves to isolate the engine from the fuel and cooling systems.
5. Emergency Shutdown: If the situation is critical, activate the emergency shutdown system.

Subsequent Actions:

1. Investigate the Cause: Once the engine has cooled down, inspect the engine for signs of overheating, oil leaks, or other abnormalities.
2. Check Oil Level and Condition: Inspect the engine oil for signs of contamination or excessive foaming.
3. Inspect Air Filter: Check the air filter for restrictions or damage.
4. Inspect Turbocharger: Examine the turbocharger for any signs of oil leaks or damage.
5. Check Oil Mist Detector: Verify the functionality of the oil mist detector.

Preventive Measures:

• Regular Maintenance: Adhere to the recommended maintenance schedule for the engine and its components.
• Oil Quality: Use high-quality engine oil and change it according to the manufacturer’s recommendations.
• Early Warning Systems: Utilize additional monitoring systems like vibration analysis or temperature sensors.

Note: These actions are general guidelines and may vary depending on the specific vessel and engine type. It’s essential to follow the ship’s emergency procedures and manufacturer’s recommendations.

A crankcase explosion relief door (CERV) is a safety device designed to protect the engine in case of excessive pressure buildup. Here are the essential components you should include in your sketch:

Main Components:

• Door Body: The main housing of the CERV.
• Door Plate: The movable part that opens under pressure.
• Spring: Holds the door plate closed under normal conditions.
• Flame Arrestor: A mesh or perforated plate designed to prevent flame propagation.
• Mounting Flanges: Used to secure the CERV to the engine crankcase.

Additional Components (optional):

• Pressure Sensing Element: Some CERVs have integrated pressure sensors to monitor crankcase pressure.
• Actuator: In more complex systems, an actuator might be used to control the door opening.

Cross-Sectional View:

To provide a clear understanding of the CERV’s operation, consider drawing a cross-section that shows the following:

• The thickness of the door plate.
• The shape and size of the flame arrester.
• The configuration of the spring and its attachment points.
• The sealing mechanism between the door plate and the door body.

By including these components in your sketch, you will provide a comprehensive representation of a crankcase explosion relief door.