NOTE
Height of termination above tank bottoms
for service tank suction tailpipes for CV/CVNs,
LHAs, and LPHs is 24 inches for wing tanks
and 12 inches for innerbottom tanks. For other
ships, the height is 12 inches.
A shut-off valve is installed in this line between
the service pump common suction header and the
service tank.
Two independent stripping systems, one hand-
operated and the other motor-driven, are installed in
each service tank. The hand operated stripping is used
for normal stripping of the service tanks. The use of
the low velocity hand operated pump eliminates tur-
bulence in the tank while stripping, which improves
the efficiency of the stripping operation. The tailpipe
for the hand operated stripping pump extends from a
maximum of 3/4-inch off the service tank bottom to
the hand operated pump in the pump room.
The motor-driven stripping system for service
tanks is primarily used to completely empty the tanks
and to remove the wash water after a cleaning opera-
tion. The tailpipe for the motor-driven stripping pump
extends from a maximum of 1 1/2-inches off the tank
bottom to the common suction header of the motor-
driven stripping pumps. This line contains a shutoff
valve, a one-way check valve, and a blank flange.
A recirculating line is installed horizontally 18-
inches off the tank bottom in the opposite end from
the suction tailpipe. This line provides a means of
returning to the service tank the recirculated fuel from
the discharge side of the service pump. A number of
1-inch holes, equally spaced along the top of the
recirculating line allow JP-5 to be returned to the tank
without disturbing the contents of the tank. Foaming
is minimized since the recirculating line is always
covered with JP-5.
Tank Inspection and Cleaning
WARNING
No person is to enter any JP-5 tank for
inspection or cleaning until the conditions for
safe entry specified by the Gas-Free Engineer
(or his authorized representative) have been
strictly complied with.
If the inspection reveals that bulkheads, stiffen-
ers, and flat surfaces have collected solids that are
readily visible, storage tanks are washed with sea
water from a firehose. Service tanks are normally just
wiped clean, but if washing is required, use fresh
water only. Wash water is removed from storage tanks
designated JP-5 or ballast by the main drainage educ-
tor, and from service tanks and storage tanks (desig-
nated JP-5 only) by the JP-5 motor-driven stripping
pumps.
The above procedures are followed if the opera-
tion is conducted at sea. If conducted in port, assis-
tance by a shore activity and changes in the wash
water removal procedure are required to prevent har-
bor pollution.
Due to the ease with which deposits can be
washed out of JP-5 tanks with a firehose, steaming is
not required nor should it be employed since the tank
coatings may be damaged.
JP-5 tanks are never cleaned by the chemical
cleaning processes using solvent-emulsifier type
compounds. Small quantities of chemical type clean-
ers remaining in the tanks will contaminate the coa-
lescer elements in the filter/separator and destroy
their coalescing ability.
When conducting the inspection and cleaning of
JP-5 tanks, refer to applicable Maintenance Require-
ments Cards for correct procedures and safety precau-
tions to be followed.
GEMS TANK LEVEL INDICATING
(TLI) SYSTEM
The Gems TLI system (fig. 4-44) consists of a
transmitter, jumper cables, receiver, and a magnet-
equipped float.
The transmitter is mounted vertically within the
tank by brackets or flanges. A voltage divider network
is located inside and extends the full length of the
transmitter assembly. This network is comprised of
magnetic reed switches tapped in at one-inch intervals
between the switch centers. The switches are con-
nected, in turn, through series resistances, to a com-
mon conductor, and by means of the cable system to
the indicating meter in the receiver. The ends of the
voltage divider are connected to the power supply
output. The power supply output is adjusted to 10
volts dc by the calibrate potentiometer in the primary
receiver.
4-53
