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