Fuel Oils; Heavy Fuel Oil (Hfo); Guiding Heavy Fuel Oil Specification - Man B&W S50MC-C8-TII Project Manual

MAN B&W

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 8217:1996 and ISO 8217:2005, British
Standard 6843 and to CIMAC recommendations
regarding requirements for heavy fuel for diesel
engines, fourth edition 2003, in which the maxi-
mum acceptable grades are RMH 700 and RMK
700. The abovementioned ISO and BS standards
supersede 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 cleaning
of the HFO, i.e. removal of water and solid con-
taminants, the fuel oil specific gravity at 15 °C (60
°F) should be below 0.991, unless modern types
of centrifuges with adequate cleaning abilities 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.
MAN B&W MC/MC-C, ME/ME-C/ME-GI/ME-B engines

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
twostroke 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
Kinematic viscosity
at 100 °C
at 50 °C
Flash point
Pour point
Carbon residue
Ash
Total sediment potential
Water
Sulphur
Vanadium
Aluminum + Silicon
Equal to ISO 8217:2005 - RMK 700
/ CIMAC recommendation No. 21 - K700
*
Provided automatic clarifiers are installed
m/m = mass
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.
MAN Diesel
7.02
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*
kg/m
3
< 1.010
cSt < 55
cSt < 700
°C > 60
°C < 30
% (m/m) < 22
% (m/m) < 0.15
% (m/m) < 0.10
% (v/v) < 0.5
% (m/m) < 4.5
mg/kg < 600
mg/kg < 80
v/v = volume
198 38 80-4.5