.scavenge fire   .sf  .scav fire

Various factors can cause scavenge fire. These are:

CAUSES OF SCAVENGE FIRE:

1. Blow past due to damaged piston ring profile and liner
2. Poor combustion due leaky fuel injector, faulty fuel pump timing
3. Leaky or improper timing of exhaust valve.
4. Wrongly timed or excessive cylinder lubrication
5. Stuffing box leak bringing system oil into scavenge space
6. Buildup of deposits due to clogged scavenge space drain by:
   1. Cylinder oilUn-burnt fuel
   1. Crankcase oil(if the stuffing box scrapper ring is fitted in wrong way)

b) Symptoms/indication:

Indications of scavenge fire are:

1. Increased exhaust temperature of affected cylinder
2. Affected unit under piston temperature high.
3. Spark emits from scavenge drain
4. Scavenge manifold noticeably hotter
5. Turbo charger may surge
6. Smoke from t/c air inlet filters when surging
7. Thick black smoke emitted at funnel
8. Engine slow down due to reduced power.

c) Action to be taken:

As EOW:

1. Immediately inform bridge and slow down main engine to ‘Dead Slow’
2. Activate Engineers’ Call Alarm
3. Shut scavenge manifold drain valve & leave vicinity

chief engineer will:

1. Request bridge for permission to stop
2. Stop engine when order received
3. Stop auxiliary blowers
4. Seal t/c air filters with canvas
5. Stop fuel oil supply to engine
6. Put the scavenge manifold fire extinguishing system into operation to extinguish the fire.
7. Open indicator cock, engage turning gear and turn engine to prevent seizure
8. Lube oil pump must be running

 Inspection Criteria after extinguishing fire:

1. After fire, remove dry deposits and sludge from scavenge space
2. Check scavenge drain pipes if clear
3. Clean and inspect the piston rods, stuffing boxes and cylinder liners.
4. Check piston and rings condition
5. Check tightness of tie rods
6. Check aux blowers non-return flaps
7. Check air cooler condition by opening the air side drain valve for possible CW leakage while cooling water is being supplied.

Prevention:

To prevent scavenge fire

1. Fuel injection equipment need to be maintained in good condition and correct injection timing
2. Maintain Piston rings in good condition and liner wear within limit
3. Maintain Cylinder oil feed rate within limits
4. Stuffing box sealing rings and scraper rings maintain in good condition
5. Keep Scavenge ports clean
6. Clean scavenge trunking and drains regularly.
7. Never use flammable materials that may vaporize, such as gas oil or kerosene, to clean inside the scavenging space.

Fire but main engine cannot be stopped:

In the event of the scavenge fire occurring and that the main engine cannot be stopped, then the following course of action would be taken:

1. Contact the Bridge and request to slow down to the lowest power possible
2. Increase the cylinder lube oil feed rate to the affected cylinder
3. Lift the fuel pump on the affected cylinder (cut off fuel), using the manual activation of the air cylinder (option fitted for fuel pipe leakage system).
4. Prepare the firefighting equipment to tackle any fire that may be emitted from the scavenge receiver relief valve.
5. Move all personnel away from the engine, should the scavenge fire burn long enough to trigger a crankcase explosion.
6. The scavenge fire should burn out, once all the oil is consumed.
7. Stop the engine as soon as possible, to allow the fire (if still burning to be extinguished) and the affected areas within the engine to be inspected.