service pump and filter separator. The service
class ships, bleed air is also provided from
system provides the capability to refuel and
the 14th stage of the GTG compressor. Bleed air
recirculate FO for the helo station. Helo defueling
is used aboard ship for starting, anti-icing, masker
capability is also provided. This capability is
air, and prairie air.
necessary because FO removed from the helo is
BLEED AIR START SYSTEM
returned to the storage tanks or diverted to a
separate contaminated FO tank. A stripping pump
Bleed air used for starting is extracted from
is provided on both types of ships for removal
of water and sludge accumulations on the bottoms
through a regulating valve. The bleed air is
of the tanks.
regulated at 75 psi and has a maximum
As with the fuel, naval distillate, stringent
temperature of 925°F. It then enters the bleed
requirements for FO purity are necessary. The
air header and is used for the various purposes
responsibility for testing the FO again belongs to
the oil king.
The CG-, and DD-class ships use
starter air differently from the FFG-class ships;
therefore, the systems differ in their method of
BLEED AIR SYSTEM
cooling the bleed air and directing it to the starter.
Bleed air, as we discussed in chapter 2 of this
On the CG-, and DD-class ships, bleed
TRAMAN, is compressed air taken from ports
air is the primary method of starting the GTEs
on different stages of the engines. On all classes
and SSGTGs. The bleed air of the four GTEs
of ships, the LM2500 GTE provides customer
and three GTGs enters a common header and
bleed air for shipboard use from the 16th
can be used to start any other engine or generator.
Refer to figure 4-9, a piping diagram of the
Figure 4-9.--Piping diagram of a DD bleed air system in the forward engine room.