The main drainage system will normally have
in the discharge piping from each compressor
the following major components:
automatically controls the starting and stopping
of the compressor based on pressure in the HP
1. Eductors of 1250 gpm capacity (in each
air main. Relief valves are provided throughout
engine room and auxiliary space).
the system to provide protection from over-
2. Suction stop-check valves (one for each
pressurization. Some uses of HP air in the
engineering plant include the following areas:
drain well and each waste water tank).
3. Deck-operated gate valves used to isolate
sections of the system. These valves are
Ship's service diesel generator (SSDG)
equipped with manual local and remote
starting
operators.
4. Discharge stop-check valves to prevent
Emergency LO coast down pump
inadvertent flooding of other spaces during
eductor operation.
Propulsion shaft brake
5. Interlocked valve manifolds to provide
Back up for LP air system
connection between the main drainage,
ballast, and firemain system.
6. Various valves, gauges, and indicating and
LM2500 GTE start
control devices to support the eductor
system.
DRAINAGE AND
The main drainage bilge pump subsystem
BALLAST SYSTEMS
serves the same drainage main as the eductor sub-
system. However, it uses an electric motor-driven
This section describes the three primary
pump to remove drainage. This system also has
systems that make up a ship's drainage system,
cross-connect fittings to provide a backup pump
the major equipment that makes up each system,
for the bilge pump installed in the oily waste water
and the function of each system in support of the
system. It allows the pump in that system to
propulsion plant. The systems are the main
backup the pump in the main drainage system.
drainage system, the secondary drainage system,
and the ballast system. The purpose of these
SECONDARY DRAINAGE SYSTEM
systems is to provide a means for dewatering the
main engine room(s) (MER) and the AMRs, as
The secondary drainage system is an in-
well as several other spaces both forward and aft
dependent fixed-eductor system primarily
of the machinery spaces. Always refer to your
associated with dewatering the following types of
ship's EOSS for detailed information on these
spaces:
systems.
The chain locker
MAIN DRAINAGE SYSTEM
The eductor rooms
The main drainage system has two types of
The magazine service rooms
subsystems, the main drainage eductor subsystem
(a fixed-eductor subsystem) and the main drainage
The guided missile launcher system
bilge pump subsystem (a positive-displacement
(GMLS) magazines
pump subsystem). The fixed-eductor subsystem
is arranged with the other main drainage sub-
The steering gear room (usually served by
system so they can be cross connected. Both
a separate drain pump, but considered part
subsystems are primarily associated with drainage
of the secondary drain system)
within the main machinery spaces and with branch
lines that serve various auxiliary space bilges
BALLAST SYSTEM
throughout the ship. The main drainage system
also takes suction from and discharges to the clean
The ballast system is used to ballast and
ballast tanks, the FO overflow and ballast tanks,
deballast clean ballast, FO overflow and ballast,
and the FO or ballast tanks through interlocked
and FO or ballast tanks. Seawater connections
manifolds for ballasting and deballasting.
4-23
