Wartsila ?31DF Series, Product Manual, Page: 114 / 216

According to fuel specification Fuel viscosity
50°C Design temperature
Equal to feed pump capacity Design flow
1.6 MPa (16 bar) Design pressure
Fineness:
6 μ m (absolute mesh size)
(ß
20
= 75, ISO16889)
- automatic filter
25
μ
m (absolute mesh size)
(ß
40
= 75, ISO16889)
- by-pass filter
Maximum permitted pressure drops at 14 cSt:
20 kPa (0.2 bar) - clean filter
80 kPa (0.8 bar) - alarm
6.4.5.5 Fine filter, MDF (1F05)
The fuel oil fine filter is a full flow duplex type filter with steel net. This filter must be installed
as near the engine as possible.
The diameter of the pipe between the fine filter and the engine should be the same as the
diameter before the filters.
Design data:
according to fuel specifications Fuel viscosity
50°C Design temperature
Larger than feed/circulation pump capacity Design flow
1.6 MPa (16 bar) Design pressure
34
μ
m (absolute mesh size)
(ß
50
= 75, ISO16889)
Fineness
Maximum permitted pressure drops at 14 cSt:
20 kPa (0.2 bar) - clean filter
80 kPa (0.8 bar) - alarm
6.4.5.6 MDF cooler (1E04)
The fuel viscosity may not drop below the minimum value stated in Technical data. When
operating on MDF, the practical consequence is that the fuel oil inlet temperature must be
kept below 45°C. Very light fuel grades may require even lower temperature.
Sustained operation on MDF usually requires a fuel oil cooler. The cooler is to be installed in
the return line after the engine(s). LT-water is normally used as cooling medium.
If MDF viscosity in day tank drops below stated minimum viscosity limit then it is recommended
to install an MDF cooler into the engine fuel supply line in order to have reliable viscosity
control.
Design data:
6-30 DBAE248994
Wärtsilä 31DF Product Guide 6. Fuel Oil System