Fuel Oils
Marine diesel oil:
Marine diesel oil ISO 8217, Class DMB
British Standard 6843, Class DMB
Similar oils may also be used
Heavy fuel oil (HFO)
Most commercially available HFO with a viscosity
below 700 cSt at 50 °C (7,000 sec. Redwood I at
100 °F) can be used.
For guidance on purchase, reference is made
to ISO 8217:2012, British Standard 6843 and to
CIMAC recommendations regarding require-
ments for heavy fuel for diesel engines, fourth
edition 2003, in which the maximum accept-
able grades are RMH 700 and RMK 700. The
abovementioned ISO and BS standards super-
sede BSMA 100 in which the limit was M9.
The data in the above HFO standards and speci-
fications refer to fuel as delivered to the ship, i.e.
before on-board cleaning.
In order to ensure effective and sufficient clean-
ing of the HFO, i.e. removal of water and solid
contaminants, the fuel oil specific gravity at 15 °C
(60 °F) should be below 0.991, unless modern
types of centrifuges with adequate cleaning abili-
ties are used.
Higher densities can be allowed if special treat-
ment systems are installed.
Current analysis information is not sufficient for
estimating the combustion properties of the oil.
This means that service results depend on oil
properties which cannot be known beforehand.
This especially applies to the tendency of the oil
to form deposits in combustion chambers, gas
passages and turbines. It may, therefore, be nec-
essary to rule out some oils that cause difficulties.
Guiding heavy fuel oil specification
Based on our general service experience we have,
as a supplement to the above mentioned stand-
ards, drawn up the guiding HFO specification
shown below.
Heavy fuel oils limited by this specification have,
to the extent of the commercial availability, been
used with satisfactory results on MAN B&W
twostroke low speed diesel engines.
The data refers to the fuel as supplied i.e. before
any on-board cleaning.
Guiding specification (maximum values)
Density at 15 °C kg/m
3
< 1.010*
Kinematic viscosity
at 100 °C cSt
< 55
at 50 °C cSt
< 700
Flash point °C
> 60
Pour point °C
< 30
Carbon residue % (m/m)
< 20
Ash % (m/m)
< 0.15
Total sediment potential % (m/m)
< 0.10
Water % (v/v)
< 0.5
Sulphur % (m/m)
< 4.5
Vanadium mg/kg
< 450
Aluminum + Silicon mg/kg
<60
Equal to ISO 8217:2010 - RMK 700
/ CIMAC recommendation No. 21 - K700
* Provided automatic clarifiers are installed
m/m = mass v/v = volume
If heavy fuel oils with analysis data exceeding the
above figures are to be used, especially with re-
gard to viscosity and specific gravity, the engine
builder should be contacted for advice regarding
possible fuel oil system changes.
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