Scavenge Fires:(What is Scavenge Fire,How Scavenge Fire occurs, Effects of Scavenge Fire,Actions to be taken if a Scavenge Fire occurs)

Scavenge Fires:

 

What is Scavenge Fire

The fire that occurs in the scavenge space (under-piston space)

 

How Scavenge Fire occurs

Cylinder Oil can collect in the scavenge space/manifold of an engine

Unburned fuel and carbon may also be blown into scavenge space/manifold due to defective piston rings or faulty timing or defective injector

All the above forms into a flammable mixture

This flammable mixture may get ignited when blow past of hot gasses occurs or when the piston becomes hot

This is called a scavenge fire

 

Effects of Scavenge Fire:

1. Loss of engine power
2. Exhaust temperature increases at the affected cylinder
3. Turbocharger may surge
4. Sparks will come out of the scavenge drains

 

Actions to be taken if a Scavenge Fire occurs:

1. Engine should be slowed down
2. Fuel should be shut off to the affected cylinder
3. Cylinder lubrication should be increased
4. Scavenge drains should be closed

A small fire will quickly burn out

If the fire persists, then

1. Engine must be stopped
2. Fire extinguishing medium should be injected into the scavenge manifold (through the fittings provided for this purpose)
3. Scavenge Manifold manhole doors should not be opened
4. Engine should be kept turning on turning gear (to prevent seizure of engine moving parts)

 

How to avoid/prevent Scavenge Fire:

1. Engine timing (fuel injection, exhaust opening, cylinder lubrication etc) and equipment maintenance should be correctly carried out
2. Scavenge manifold should be regularly inspected and cleaned
3. During the inspection, if carbon or oil is found in the scavenge manifold, its source should be detected and the fault should be rectified

Scavenge drains should be regularly blown. If any oil discharges is found its source should be detected and the fault should be rectified