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°CDew point temperature
1 mg/m
3
Max. oil content
3 µmMax. particle size
8.2 Internal compressed air system
All engines 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 main starting valve is built on the engine and can be operated both
manually and electrically.
All engines have built-on non-return valves and flame arrestors. The engine can not be started
when the turning gear is engaged.
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.
In addition to the starting system, the compressed air system is also used for a number of
control functions. There are separate connections to the external system for these functions.
To ensure correct operation of the engine the compressed air supply, high-pressure or
low-pressure, must not be closed during operation.
Wärtsilä 46F Product Guide - a19 - 1 December 2017 8-1
8. Compressed Air SystemWärtsilä 46F Product Guide
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