Wartsila ?31DF Series, Product Manual, Page: 135 / 216

8. Compressed Air System
Compressed air is used to start engines and to provide actuating energy for safety and control
devices. The use of starting air for other purposes is limited by the classification regulations.
To ensure the functionality of the components in the compressed air system, the compressed
air has to be free from solid particles and oil.
8.1 Instrument air quality
The quality of instrument air, from the ships instrument air system, for safety and control
devices must fulfill the following requirements.
Instrument air specification:
1 MPa (10 bar) Design pressure
0.7 MPa (7 bar) Nominal pressure
+3°C Dew point temperature
1 mg/m 3 Max. oil content
3 µm Max. particle size
8.2 External compressed air system
The design of the starting air system is partly determined by classification regulations. Most
classification societies require that the total capacity is divided into two equally sized starting
air receivers and starting air compressors. The requirements concerning multiple engine
installations can be subject to special consideration by the classification society.
The starting air pipes should always be slightly inclined and equipped with manual or automatic
draining at the lowest points.
Instrument air to safety and control devices must be treated in an air dryer.
DBAE248994 8-1
8. Compressed Air System Wärtsilä 31DF Product Guide