Marine Installation Manual
2021-08
4-11
4 Ancillary Systems
4.2 Cooling water system
X72DF
To supply the cooling water system with the desired static pressure and compen
-
sate for the cooling water volume change during engine operation, WinGD pro
-
poses two possible solutions, namely installing either an expansion tank or a
buffer unit.
Expansion tank
To ensure that the required static head is applied to the cylinder cooling water
(CCW) system, the expansion tank is to be fitted at least 13.5m above the highest
point of the engine’s cooling water piping. The tank is to be connected by a bal
-
ance pipe to the CCW pump suction.
Buffer unit
The installation of a buffer unit is an alternative solution. The buffer unit has the
advantage of variable static pressure settings and location flexibility. However, it
does require an additional water supply pump.
Main components and functionalities of the buffer unit:
•
Control air shut-off valve
(DN15), solenoid type, controlled by the signal
from the Level Switch Low (LSL). This valve is normally open but to be
shut off when the signal from the LSL is triggered and water feeding is
started.
•
Control air pressure regulating valve
(DN15), with pressure reduction and
air release function. This valve reduces the control air pressure to the de
-
sired buffer unit pressure. It enables air to be released to maintain the pres
-
sure when the buffer unit water volume is increasing (refill or water
expansion). The pressure setting of the buffer unit is targeted to ensure that
the cooling water pressure at the ME inlet fulfils the WinGD specification
requirement.
•
Safety valve
(DN32), to be set at approximately 0.5 bar above the buffer
unit set pressure.
•
High-level switch
and
low-level switch
:
º
The LSL is set at approximately 35 % of the total volume of the buffer
unit. When the LSL is triggered, a signal is emitted simultaneously to
the control air shut-off valve and the buffer unit supply pump to start.
º
The Level Switch High (LSH) is set at approximately 65% of the total
volume of the buffer unit. When the LSH is triggered, a signal is emitted
to stop the buffer unit supply pump.
º
The volume difference between the LSH and the LSL must not be less
than 150 litres.
•
LAH
and
LAL
, high-level alarm and low-level alarm:
º
The LAH must be set at approximately 70% of the total volume of the
buffer unit.
º
The LAL must be set at approximately 30% of the total volume of the
buffer unit.
