Marine Installation Manual
2021-08
4-88
4 Ancillary Systems
4.8 Leakage collection system and washing devices
X72DF
The piston underside drain is collected in the sludge oil trap. The flow is ensured
by venting some air at the top of the sludge oil trap and through an orifice (5 to
10 mm inner diameter) to the atmosphere. In addition, a sight glass is installed in
the venting pipe to check the air flow. An external heating device at the bottom
of the sludge oil trap must be installed to ensure that the sludge emulsion can be
properly drained through the manual bottom drain, which is activated by
opening a manual valve.
There is a high-level alarm to inform the crew to drain the sludge oil trap.
Direct drain to the
sludge oil tank
If the manual bottom drain is connected to the sludge oil tank, which is inte
-
grated in the double bottom structure, then the draining of the sludge will be
pushed by scavenge air pressure and gravity. However, the manual bottom-drain
valve must be closed quickly and as soon as the sludge oil trap becomes empty.
Otherwise, the sludge oil tank will become pressurised by the scavenge air.
Transfer to the
sludge oil tank by pump
If the manual bottom drain is connected to the intake of the sludge oil pump,
then the sludge emulsion will be transferred to the sludge oil tank by this pump.
The advantage of this solution is that the sludge oil tank can be installed at a dif
-
ferent height than the double bottom level, while at the same time ensuring that
the sludge oil tank will not be pressurised by opening the manual bottom drain.
Manual sludge removal
For manual sludge removal, partially unscrew and lift the cover to first drain the
liquid to a tray, and then fully open the cover and manually remove the sludge.
A design proposal for the manually bottom-drained sludge oil trap is provided in
Figure 4
-
48 Design proposal of a manually bottom-drained sludge oil trap
SM-0771
Sludge oil drain
from piston underside
Heating media inlet
to the internal
heating coil
Drain to sludge oil
tank or to sludge
oil pump
Sight glass
Orifice 5 - 10 mm
Manual bottom-drain valve
Level Alarm, High
(LAH)
Pressure gauge
Thermometer
Heating media outlet
