these components. Refer to chapter 5 for additional
ships, the GSEs perform the maintenance on
information on troubleshooting a motor-operated valve.
motor-operated valves. Depending on the class of ship,
however, this task may be the responsibility of the GSEs
Fuel Filter/Coalescers
or EMs.
Fuel filter/coalescers are installed in the ship's ser-
TROUBLESHOOTING.-- You can locate the
vice fuel system to filter out solid particle contamination
faults in a motor-operated valve by using the same
and to coalesce and remove all suspended water. These
troubleshooting procedures we discussed for motors
units combine the processes of filtration of solids and
and controllers. These faults are usually caused by short
separation of immiscible liquids in two successive
circuits, open circuits, or grounds. Since a motor-
stages. On the DD-963, DDG-993, and CG-47 class
operated valve is an electromechanical device, many
ships, fuel filter/coalescers have an electrical control
problems can be traced to the interface between the
box that controls the automatic shifting of the unit. On
c o n t r o l l e r and the gear drive system. Mechanical
the DD-963 and DDG-993 class ships, the electrical
failures in motor-operated valves are not uncommon.
control box is located behind the instrument panel and
The GSE is usually called to locate and repair faults in
contains the electrical control circuit. (See fig. 4-2,
Figure 4-2.--Fuel oil filter/coalescers.
4-3
