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 TM 55-1905-219-14-1
SEWAGE SYSTEM PIPING.
a. The Sewage System Piping (Figure FO-23) consists of one urinal, two water closets, one holding tank, one
deck connection with valve for sewage discharge hose, two 4-inch overboard discharges with scuppers, two macerators,
one three-way port valve, two sewage pumps, one air pump, and piping and fittings.
b. The holding tank is located at Frame 42, Starboard. The tank has connectors for sewage-in, sewage
discharge and vents. It is also equipped with a switch, located at the 90% full mark which sets off an audible alarm in the
Pilothouse when tripped.
c. The holding tank is vented at Frame 43-1/2, Starboard with a single 2-inch line to the outside air. The
Sewage Drainage System is also vented by a 2-inch line to weather located at Frame 44, Starboard.
d. A three-way port valve is installed in the system just after the two macerators. The valve allows waste to be
routed to the holding tank, or directly overboard when full.
e. A 2-inch deck discharge connection is provided at Frame 42, Port. This connection is fitted with a 2-inch cam
lock for securing a sewage discharge hose. A 2-inch ball valve is also provided.
f. Two sewage pumps are set in parallel for discharging sewage. They are located approximately 2-feet 8-
inches (0.81 m) Starboard of ship centerline, at Frames 41 and 43. Each of these pumps, along with local controls, is
provided with two remote switches.
g. The System is also equipped with a sewage tank air pump. It is located at Frame 41, starboard. It is
controlled by a local switch which is left in the "AUTO" position while the craft is in operation. The system will work
automatically only when needed.
h. The Shipboard Collection Disposal System consists of four main assemblies; water closets, urinal, discharge
valve and collection tank, and piping which uses vacuum or differential pressure to move the flushed 'black-water' to the
collection tank. A control panel located on the collection tank assembly provides for semi-automatic operation of the
collection system.
i. Vacuum pumps empty the collection tank and influent lines to the water closets and urinal discharge valve.
When the water closet valve is started and opened, the sewage is pushed through the influent line or piping to the
collection tank. Liquid level sensors control the level indicator lights. Hand operated valves are located throughout the
system to direct flow for various methods of operation. They also are used to isolate components requiring servicing or
maintenance. In an emergency, the tank can be emptied by air pressure applied at the tank top.
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