Fire anywhere on ship is deadly and dangerous, fire could be on deck or in the engine room. Let us talk particularly about fire in engine room. Fire in engine room is more dangerous as engine room is full of machines, oils, lubricants and what not. One of the main cause of engine room fire is scavenge fire, In this article, we will discuss about scavenge fire, everything from causes to actions to be taken.
Before we talk about causes of scavenge fires let us revisit the basics of fire triangle. If fire triangle has to be put in one line, then for a fire to occur three things are required, namely Oxygen, heat source and fuel.
Causes of Scavenge Fire
- Cylinder oil can accumulate in the scavenge space of an engine.
- Unburnt fuel and carbon may also be blown into scavenge space as a result of defective piston rings, injectors etc.
- Slack, worn or broken piston rings may cause part of hot gases to blow from the cylinder.
- Defective sealing of stuffing box causing crankcase oil to gain access into the scavenge.
- Dirty scavenge space
- Cylinder lubrication may be insufficient or may be excessive.
Indication of Scavenge Fire
- Excessive black smoke.
- High exhaust temperature and coolant temperature of the unit affected.
- Sparks from scavenge drains of affected units.
- Surging and uneven running of turbochargers.
- Drop in RPM due to loss of power.
Actions To Be Taken In Case Of Small Scavenge Fire
- Close all scavenge drains of the units concerned.
- Cut off the fuel, this will reduce the temperature.
- Increase cylinder lubrication to avoid seizing.
- Slow down engine. Localised fire will burn itself out.
- Keep monitoring the temperature of scavenge.
Actions To Be Taken In Case of Large Scavenge Fire
- Slow down the engine to dead slow before finally stopping the engine. Keep engine turning or turn the turning gear to prevent seizure and continue manual lubrication of liners.
- Keep the coolant /lubricant pump on, they will carry heat away from the fire.
- Switch off any blower and cover the air intakes and shut the exhaust fire dampers to stop the ingress of fresh air to the fire.
- Use the installed CO2 smothering system for the scavenge spaces.