the firemain) and the discharge head (how far above the
C o n c e r n f o r t h e e nv i r o n m e n t i s ex t r e m e l y
eductor the water has to rise to be removed). When
important, and various pollution laws have been
observing the eductor operation, you must be aware
enacted. Federal law prohibits the discharge of oil into
that not all of the eductor discharge is supplied from the
inland or coastal waters, and there are restrictions
compartment being dewatered. A large percentage of
pertaining to shipboard discharges on the high seas. The
this discharge is the actuation water supplied by the
engineering officer of the watch (EOOW) must give
firemain
permission for eductor operation.
NOTE
Fixed eductors are installed in the ship's main
drainage system and are normally used to dewater
Oils and flammable liquids are not
bilges. Fixed eductors are normally of the perijet
normally permitted to be discharged
design with no suction strainers installed. A
overboard and should be disposed of
cross-sectional view of a perijet eductor is shown in
according to environmental regulations.
figure 5-36.
There are other factors, which may affect eductor
Portable eductors can be rigged as required to
operation. The condition of the suction piping must be
dewater a compartment or space. They are often used
inspected periodically for deterioration, and all joints
with the P-100 pump to dewater compartments.
and flanges should be tight. Air entering the suction
Figure 5-37 shows one arrangement that could be
piping will prevent the eductor from operating properly.
used. In this arrangement both the P-100 pump and the
Drainage valve misalignment in other spaces will affect
e d u c t o r a r e r e m ov i n g wa t e r f r o m t h e f l o o d e d
eductor operation as well. You may unknowingly be
compartment.
removing water from the bilges in an adjacent space
instead of the intended compartment. Proper supply
PORTABLE AFFF IN-LINE EDUCTORS
pressure from the firemain must be substantially higher
than the pressure against which the eductor is required
The portable in-line eductor is used to mix
to operate. If the pressure is not high enough to be
seawater and AFFF concentrate to produce an AFFF
discharged overboard, it will simply back up through the
solution for combating fires especially class BRAVO
eductor into the space, actually increasing the rate of
fires. The eductor consists of a bronze body with an
flooding in the compartment. Improper valve lineups
internal ball check valve and flexible pickup tube
may actually cause flooding in other compartments.
assembly. The eductor is used in conjunction with a
When using the eductor, posted operating procedures,
95 gpm vari-nozzle. Seawater passing through the
or Engineering Operational Sequence System (EOSS)
eductor creates a suction in the pickup tube assembly
(if installed), is mandatory.
which, in turn, draws AFFF concentrate from a
Installed eductors function to create a vacuum in
5-gallon can or 55-gallon drum (fig. 5-38). The eductor
suction piping, removing water from bilges, either in the
mixes the AFFF concentrate and seawater at
compartment where they are located or remotely.
approximately 6 percent ratio when the inlet pressure
Unattended operation, especially in remote spaces, may
to the eductor is 100 psig. Continuous use will require
asphyxiate personnel working in the compartment.
about 5 gallons of AFFF concentrate per minute.
Train personnel working in confined or closed spaces to
In-line eductors should be connected directly to fire
recognize the potential for hazards of asphyxiation.
plugs to minimize inlet pressure reduction due to
WARNING
friction loss. Friction loss downstream of the eductor
can create sufficient backpressure so the AFFF suction
Eductors located in remote spaces, if
will cease to operate, but seawater will continue to flow.
activated, can remove all breathing air,
Users of the in-line eductor must limit the hose length
particularly if ventilation is secured,
downstream of the eductor to three lengths (150 feet)
inadequate, or not installed. Ensure sufficient
when fighting fires in the horizontal plane or advancing
make-up air is provided and the space has
up not more than one deck. When the AFFF eductor is
adequate oxygen before entry in all
rigged on a deck above the deck where the fire is being
eductor-equipped remote spaces. Maintain
fought (as in machinery space re-entry), up to six
communication with personnel working inside
lengths of hose (300 feet) may be connected
the remote space while eductor operation is in
downstream of the eductor.
progress.
5-20
