Causes
of scavenge fire
Precautions to be taken to avoid scavenge fire
ref: introduction to marine engineering by D A Talyor
- Cylinder oil can collect in the scavenge space of an engine.
- Unburned fuel and carbon may also be blown into the scavenge space as a result of defective piston rings, faulty timing, a defective injector, etc
- A build-up of this flammable mixture presents a danger as a blow past of hot gases from the cylinder may ignite the mixture, and cause a scavenge fire.
Symptoms
for scavenge fire
- A loss of engine power will result,
- high exhaust temperatures at the affected cylinders.
- The affected turbo-chargers may surge and
- sparks will be seen at the scavenge drains.
Actions
to be taken when scavenge fire occurs
- Once a fire is detected the engine should be slowed down,
- shut off fuel for the affected cylinders and cylinder lubrication increased.
- All the scavenge drains should be closed.
- A small fire will quickly burn out, but where the fire persists the engine must be stopped.
- A fire extinguishing medium should then be injected through the fittings provided in the scavenge trunking.
- On no account should the trunking be opened up.
Precautions to be taken to avoid scavenge fire
- To avoid scavenge fires occurring the engine timing and equipment maintenance should be correctly carried out.
- The scavenge trunking should be regularly inspected and cleaned if necessary.
- Where carbon or oil build up is found in the scavenge, its source should be detected and the fault remedied.
- Scavenge drains should be regularly blown and any oil discharges investigated at the first opportunity.
ref: introduction to marine engineering by D A Talyor