MAN B&W L28/32H, Manual

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08028-0D\H5250\94.08.12
B 11 00 0 Fuel Oil Cleaning Recommendations
General
Centrifuging
Fuel oils should always be considered as contami-
nated upon delivery and should therefore be
thoroughly cleaned to remove solids as well as liquid
contaminants before use.
The solid contaminants in the fuel oil are mainly rust,
sand, dust and refinery catalysts. Liquid contami-
nants 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 lead to increased
cylinder liner wear and deterioration of the exhaust
valve seats. Also increased fouling of gas ways and
turbocharger blades may result from the use of
inadequately cleaned fuel oil. Effective cleaning can
only be ensured by using a centrifuge.
We recommend that the capacity of the installed
centrifuge should, at least, be according to the
centrifuge maker's instructions.
Cleaning of distillate fuel such as ISO 8217 classes
DMX to DMB is generally not necessary. But han-
dling of a liquid fuel on board ships gives a risk of
contamination with sea water. Therefore it is a good
idea to centrifuge all fuel on board ships.
Fuel classes DMC to RMH55 require a treatment
with centrifuge in all cases.
Automatic centrifuges must be used. Fuel types
RMK35 to RMK55 require centrifuges capable to
handle up to 1010 kg/m
3
density.
To obtain optimum cleaning it is of the utmost impor-
tance that the centrifuge is operated with a fuel oil
viscosity as low as possible, i.e. that the highest
possible temperature is maintained in the centrifuge
oil preheater.
Supplementary Equipment
Experience proves that if the centrifugal installation
is dimensioned and installed correctly – and oper-
ated correctly according to the supplier's instructions
– this is a sufficient way of cleaning the fuel.
All supplementary equipment, such as the 10 m
m
nominal filter, will have a positive effect and may
contribute to longer intervals between overhauls.
Also, supplementary equipment will reduce the op-
eration costs.
This equipment can give difficulties if incorrectly
installed, However if correctly installed and operated
can with some fuels give benefits in lower wear and
sludge formation.
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