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
Internal compressed air system
All engines, independent of cylinder number, are started by means of compressed air with a nominal pressure
of 3 MPa (30 bar). The start is performed by direct injection of air into the cylinders through the starting air
valves in the cylinder heads. The master starting valve, built on the engine, can be operated both manually
and electrically.
The starting air system is equipped with a slow turning valve, which rotates the engine slowly without fuel
injection for a few turns before start. Slow turning is not performed if the engine has been running max. 30
minutes earlier, or if slow turning is automatically performed every 30 minutes.
All engines have built-on non-return valves and flame arrestors. The engine can not be started when the
turning gear is engaged.
Product Guide Wärtsilä 34DF - 3/2012
79
Product Guide
8. Compressed Air System
