Oil Mist And Crankcase

Question 1

As EOOW, Explain the procedure to be followed in the event of a crankcase oil mist alarm on a bridge controlled, constant speed, main propulsion engine fitted with a controllable pitch propeller

Answer 1

1), Verify the Alarm - Confirm its genuine.
2), Raise the Alarm - Inform bridge and engine control room.
3), Ensure Fuel and Air Supply has been Isolated.
4), Evacuate the Engine Room.
5), Wait 20-30mins before re-entry. (take great care)
6), Open Ventilation - (Sky doors, fans, etc)
7), Wait until engine has fully cooled before opening crankcase doors.
8), Get a fire team on standby.
9), Inspect the crankcase carefully, but treated as an enclosed space.
10), Engage Turning Gear & Open Indicator Cocks.

Question 2

with reference to main engine crankcase explosions,
State TWO Causes

Answer 2

• Badly Damaged Stuffing Box
• Main Bearing Overheating
• Ignition of Oily Mist

Question 3

with reference to main engine crankcase explosions,
Explain how the effects can be minimised

Answer 3

PREVENTIVE MEASURES
1), Avoid Overloading the Engine - This prevents excessive wear and overheating of components.
2), Regular Inspections - Looking for signs of wear or rubbing is key to early detection.
3), Oil Mist Detector (OMD) - Its crucial to monitor mist levels, as oil mist is highly explosive.
4), Routine OMD Checks and Maintenance - Ensures its calibrated and working properly.
5), Control of Lubricating Oil Water Content - Reduces false alarms and ensures proper lubrication.
PROTECTIVE MEASURES
Crankcase Relief Doors - These are safety devices designed to relieve internal pressure safely in the event of an explosion, minimizing structural damage and protecting personnel.

Question 4

State the name of the equipment used to give a warning of the presence of conditions that could lead to an explosion in the crankcase of a diesel engine

Answer 4

• Oil Mist Detector (OMD)

Question 5

Sketch & Describe the device used to relieve any excess pressure that might develop as a result of a crankcase explosion in a dispel engine

Answer 5

INSERT SKETCH

Crankcase Relief Valve
- It releases excess internal pressure from the crankcase.
- It also prevents the flame inside the crankcase from coming out and causing further damage.

Question 6

As EOOW, Explain the procedure to be followed in the event of a crankcase oil mist alarm on a bridge controlled, constant speed, main propulsion engine fitted with a controllable pitch propeller

Answer 6

1), Verify the Alarm - Confirm its genuine.
2), Raise the Alarm - Inform bridge and engine control room.
3), Ensure Fuel and Air Supply has been Isolated.
4), Evacuate the Engine Room.
5), Wait 20-30mins before re-entry. (take great care)
6), Open Ventilation - (Sky doors, fans, etc)
7), Wait until engine has fully cooled before opening crankcase doors.
8), Get a fire team on standby.
9), Inspect the crankcase carefully, but treated as an enclosed space.
10), Engage Turning Gear & Open Indicator Cocks.