CHT System Labeling
locally while the system is being serviced. In some
installations, the CHT pump-room area is equipped
All CHT system components are labeled and
with a flooding alarm that is monitored at a remote
marked according to General Specifications for Ships
of the United States Navy, NAVSEA 0902-001-5000.
Piping that passes through unmanned spaces, such
The level sensors are the mercury-float type.
as tanks, voids, and cofferdams, is marked at least
However, pressure diaphragm sensors were used on
once in each space. Piping in machinery spaces is
earlier systems. The mercury-float type is the better
marked at least twice; at its point of entry and exit.
of the two. Mercury is contained in two metal
The pipes should be stenciled to identify the system
capsules (switches) that are encased in each
and the direction of flow. Valves and remote
polyurethane float. Normally, only one switch in
operating devices are labeled by service and position
each float is used and the contact closes when it is
for system operating modes. The damage control
in the horizontal position.
classifications are to be plainly marked. Handwheel
of valves in sewage piping systems are to be painted
T h e pressure-diaphragm type requires a
gold. (See NSTM, chapter 505.) The drains are
9-inch head to close and a 3-inch head to open. A
marked to show the type of service, such as soil,
rubber diaphragm deflects and closes the switch.
waste, and garbage grinder drains.
These switches had problems, so ships were
recommended to request an Alternation (AER) Kit
Mercury Float 2-S4320-LL-HAL-218. NAVSEA
recommends that all sensors be changed to the
Washup facilities, including a sink with hot and
cold water, soap, disinfectant, and hand drying
facilities are located in or near the pump room.
Sewage Transfer Hoses
The sink drains into the sump in the pump room.
The sump is emptied by either an installed saltwater
The sewage transfer hose is used to transfer
eductor or by a sump pump. The water is
sewage from the ship's deck riser to the shore
discharged into the CHT pump discharge line.
connection. The hose is 4 inches in diameter. Two
types of hose are available: collapsible and
The pump room and deck discharge stations
have a source of saltwater to wash up a sewage spill.
The collapsible hose is the most common of the
Further information on washup procedures and
two. Public works centers (PWCs) have trucks with
materials was provided earlier in this chapter under
hose reels mounted in the truck beds. The
the heading Sanitation.
collapsible hoses lie flat, and several hoses may be
stored on a single hose reel. When the ship enters
port, PWC will furnish the hose and make the
connections on shore. The ship's personnel will
Fire-fighting equipment must be provided at or
make the connection on board the ship.
near CHT spaces in case of an emergency. The
CHT tank may contain toxic and/or combustible
A noncollapsible hose is also available. It is a
gases which can be hazardous.
full bore hose that is wire reinforced and has a rigid
body. This hose is superior to the collapsible hose
in one respect-it does not kink up and restrict the
flow of sewage.
A telephone connection to the ship's internal
communication system is located in the pump room.
Both types of hoses have cam-locking couplings
Another is located at the continuously manned
with male and female end fittings. Both types of
remote location where the high-level alarm is
hoses are interchangeable with each other. Before
monitored. In addition, telephone communication
any hose is disconnected, it must be flushed for 10
at each deck discharge connection is required
minutes to eliminate any sewage.
whenever the operating mode of the CHT system is
changed. The X52J sound-powered phone circuit is
used at these locations.