Water In Oil Monitoring System; Liner Wall Monitoring System - Man B&W S50MC-C8-TII Project Manual

MAN B&W

Water In Oil Monitoring System

In case the lubricating oil becomes contaminated
with an amount of water exceeding our limit of
0.2%, acute corrosive wear of the crosshead bear-
ing overlayer may occur. The higher the water con-
tent, the faster the wear rate.
To prevent water from accumulating in the lube
oil and, thereby, causing damage to the bearings,
the oil should be monitored manually or automati-
cally by means of a Water In Oil (WIO) monitoring
system connected to the engine alarm and moni-
toring system. In case of water contamination
the source should be found and the equipment
inspected and repaired accordingly.
The WIO system should trigger an alarm when
the water content exceeds 0.2%, and preferably
again when exceeding 0.35% measured as abso-
lute water content.
Some WIO systems measure water activity, ie
the relative availability of water in a substance
expressed in 'aw' on a scale from 0 to 1. Here, '0'
indicates oil totally free of water and '1' oil fully
saturated by water. The correlation to absolute
water content in normal running as well as alarm
condition is as follows:
Engine condition
High alarm level
High High alarm level
K98MC6/7, S42MC7, S35MC7, L35MC6 and
S26MC6 as well as all MC-C engines are as
standard specified with Water In Oil monitoring
system.
Please note: Corrosion of the overlayer is a poten-
tial problem only for crosshead bearings, because
only crosshead bearings are designed with an
overlayer. Main and crankpin bearings may also
suffer irreparable damage from water contamina-
tion, but the damage mechanism would be differ-
ent and not as acute.
MAN B&W MC/MCC engines
Abs. water Water
content, % activity, aw
0.2 0.5
0.35 0.9

Liner Wall Monitoring System

The Liner Wall Monitoring (LWM) system moni-
tors the temperature of each cylinder liner. It is to
be regarded as a tool providing the engine room
crew the possibility to react with appropriate
countermeasures in case the cylinder oil film is
indicating early signs of breakdown.
In doing so, the LWM system can assist the crew
in the recognition phase and help avoid conse-
quential scuffing of the cylinder liner and piston
rings.
Signs of oil film breakdown in a cylinder liner
will appear by way of increased and fluctuating
temperatures. Therefore, recording a preset max
allowable absolute temperature for the individual
cylinder or a max allowed deviation from a calcu-
lated average of all sensors will trigger a cylinder
liner temperature alarm.
The LWM system includes two sensors placed in
the manoeuvring and exhaust side of the liners,
near the piston skirt TDC position. The sensors
are interfaced to the ship alarm system which
monitors the liner temperatures.
For each individual engine, the max and deviation
alarm levels are optimised by monitoring the tem-
perature level of each sensor during normal serv-
ice operation and setting the levels accordingly.
The temperature data is logged on a PC for one
week at least and preferably for the duration of a
round trip for reference of temperature develop-
ment.
All types 98 and 90 MC and MC-C engines are
as standard specified with Liner Wall Monitoring
system. For all other engines, the LWM system is
available as an option: 4 75 136.
MAN Diesel
18.06
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