Scavenge Fire

What would you do in the event of a Scavenge Fire?

If a Scavenge Fire were to start, the two main objectives are to confine the Scavenge Fire to the Scavenge Space and to minimise damage to the Engine.

In the event of the Fire breaking out, inform Bridge that the Engine is to be brought to Dead Slow Ahead and also inform the Chief Engineer.

The Fuel should be cut off to that particular Cylinder.  The Cylinder Lub Oil should be increased to prevent seizure and wear.

If Fixed Fire Fighting Equipment is attached to the Scavenge Trunking, this can be brought into operation, depending on severity of situation.  But in most cases the Fire will generally subside within 5-15 minutes.

Once the Fire is out and Navigational Circumstances allow it, the Engine must be Stopped.

Do not open Scavenge Space Doors or Crankcase Doors before Site of Fire has cooled down.  When opening up, care must be taken to keep clear of any flame.

After opening up, all scavenge spaces must be thoroughly cleaned and all debris removed.  The Piston Rods and Cylinder Liner should be examined for surface blemishes, straightness, etc., and the Diaphragm Glands (Stuffing Box) examined to ensure that they are operational and not damaged.

Also Piston Rings should be checked, as Blow By may have been the Ignition Source of the Fire.  If possible the Piston Head in question should be renewed at the earliest possible moment and the damaged Unit overhauled.

On Engines fitted with Tie Bolts, it may be necessary to re-tighten the Bolts adjacent to the Fire.

When starting the Engine again, care must be taken after switching on the Fuel to the Cylinder in question, and that also the Cylinder Lub Oil quantities are reduced to normal

Heavy Oil Fuel System from Bunker Tanks to Engine.

Heavy Oil Fuel System from Bunker Tanks to Engine.

Fuel is pumped from the Fuel Oil Double Bottoms via a Transfer Pump to a Fuel Oil Settling Tank where it is heated.

  The Fuel Oil Purifiers/Centrifuges take suction from the Settling Tank via Purifier Heaters, pass through the Purifiers, where any water and impurities are removed and passed on to the Service Tank which also has a set of Heating Coils.

From the Service Tank the Fuel then passes via a Flowmeter to the Mixing Tank, from where the Booster Pumps take suction, discharging to the Fuel Oil Heaters, where the correct Fuel Oil Temperature/Viscosity is achieved for correct Fuel Combustion in the Engine. 

  The Fuel then passes through the Viscosity Regulator which controls the Heater Temperature, then on to the Fuel Oil Filters (which are heated), to the Fuel Pumps, then to the Fuel Injectors via Double Skin/Wall High Pressure Pipe.

Any surplus Fuel returns via a Regulating Valve from the Fuel Pumps back to the Mixing Tank.

Diesel Oil can also be used in the System and is fed to the System via a three-way valve.

 When Diesel is used, no heating is required

Main Engine Oil Sump Level Rising?

What Action would you take in the event of the Main Engine Oil Sump Level Rising? 

  What could be the Problem and how would you fix it?

The action to be taken would depend on how fast the level was rising and what was causing it to rise.

It could be due to the Lub Oil Filling Valve being left open.

But, if it were due to Water or Fuel entering the Sump, the Engine would have to be Stopped as soon as it was Safe to do so.

Tests would be carried out to tell if it were Water or Fuel.

If it were Fuel, you can normally smell this in the Oil, but a Flow Stick Test can be done.

Water has a tendency to form the colour of the Oil, depending on extent of contamination.

If it were Fuel, the most likely cause would be a faulty Injector; therefore it would be changed.

If it were Water, it could be coming from a Cracked Liner or Liner 'O' Rings, therefore possible Liner change to solve the Problem.

The Oil may have to be changed, depending on extent of Contamination, but the Lub Oil Purifier may be able to cope with it. 

GENERAL SAFETY HINTS ON BOARD 

DO NOT DEVIATE FROM ANY WRITTEN PROCEDURE OR INSTRUCTION
AS THEY ARE IN ORDER TO IMPROVE SAFETY AND PROTECT
ENVIRONMENT FROM RISK OF POLLUTION.

THE MAJORITY OF ACCIDENTS ARISE BECAUSE RECOGNIZED SAFE WORKING PRACTICES OR COMPANY PROCEDURE ARE IGNORED.

UNI FUEL SYSTEM

Uni means one.
Uni fuel means one fuel system for both generators and for main engine

Fuel Oil System
- the ‘Unifuel’ system
MAN B&W Diesel’s two-stroke low speed diesel
engines and MAN B&W Holeby four-stroke diesel
GenSets are designed to operate in accordance with
the unifuel principle, i.e. with the same fuel for both
main and auxiliary diesels.
For guidance on purchase, reference is made to ISO
8217, BS6843 and to CIMAC recommendations
regarding requirements for heavy fuel for diesel
engines, edition 1990. From these, the maximum
accepted grades are RMH 55 and K55. The
mentioned ISO and BS standards supersede BS MA
100 in which the limit is M9.
Based on our general service experience, and as a
supplement to the above-mentioned standards, we
have prepared a guiding fuel oil specification, shown
in Fig. 8. Fig. 9. Heavy fuel oil treatment concept
Density 15°C kg/m³ 991 *
Kinematic viscosity
at 100°C cSt 55
at 50°C cSt 700
Flash point °C ³60
Pour point °C 30
Carbon residue %(m/m) 22
Ash %(m/m) 0.15
Total sediment after ageing %(m/m) 0.10
Water %(v/v) 1.0
Sulphur %(m/m) 5.0
Vanadium mg/kg 600
Aluminium+ silicon mg/kg 80
Equal to ISO 8217/CIMAC - H55
* 1010 provided automatic modern clarifiers are
installed
Fig. 8. Guiding fuel oil specification
On heavy fuel oil research we have, in Copenhagen
and on board ship, run several tests with modified
injection equipment to establish a basis for experience
and confirm development within injection
equipment, fuel treatment before injection, and
emission. In 1995, a representative from MAN B&W
Diesel has been elected chairman of the CIMAC
Heavy Fuel Oil working group.
The common system covers the entire fuel oil flow
from storage tank to injection into the engine cylinders.
With regard to centrifuge recommendations, fuel oils
should always be considered as contaminated upon
delivery and should therefore be thoroughly cleaned
to remove solid as well as liquid contaminants before
use. The solid contaminants in the fuel are mainly
rust, sand, dust and refinery catalysts. Liquid contaminants
are mainly water, i.e. either fresh water or
salt water.
Impurities in the fuel can cause damage to fuel
pumps and fuel valves, and can result in increased
cylinder liner wear and deterioration of the exhaust
valve seats. Also increased fouling of gasways and
turbocharger blades may result from the use of
inadequately cleaned fuel oil.
Effective cleaning can only be ensured by using a
centrifuge.
Results from experimental work on the centrifuge
treatment of today’s residual fuel qualities have
shown that the best cleaning effect, particularly in
regard to the removal of catalytic fines, is achieved
when the centrifuges are operated in series, i.e. in
purifier/clarifier mode.
This recommendation is valid for conventional centrifuges.
For more modern types, suitable for treating
fuels with densities higher than 991 kg/m3 at 15°C, it
is recommended to follow the maker’s specific
instructions.
In view of the fact that some fuel oil standards
incorporate fuel grades without a density limit, and
also the fact that the traditional limit of 991 kg/m3 at
15°C is occasionally exceeded on actual deliveries,
some improvements in the centrifuging treatment
have been introduced to enable the treatment of
fuels with higher density.
With such equipment, adequate separation of water
and fuel can be carried out in the centrifuge, for fuels
up to a density of 1010 kg/m3 at 15°C. Therefore, this
has been selected as the density limit for new high
density fuel grades.
Thus high density fuels are fully acceptable for our
engines provided that appropriate centrifuges are
installed. They should be operated in parallel or in
series according to the centrifuge maker’s instructions