generated by jet exhaust. An orifice located in the
return line connection of each module controls the flow
rate of cooling water within the module assemblies. A
removable hinge protector plate located below the
bottom module of each panel assembly, permits easy
access to the hinge bearing and fitting for maintenance.
Cooling Water Piping Installation
The cooling water piping installation (fig. 5-5)
consists of a strainer, swivel joint assemblies, orifice
flange assemblies, temperature switch, pressure switch,
pressure gauges and associated piping and connections.
Seawater, supplied by the ship’s firemain, is
continuously circulated through each module assembly
and then discharged overboard. The strainer removes
particles, which could clog water passages in the
modules. The swivel joint assemblies provide a means
of connecting the water manifolds, via hoses, to the
seawater supply piping. The swivel joint also permits
rotational movement of the piping as the JBD is raised
or lowered. Two orifices flange assemblies are provided
to regulate the cooling water flow rate. The inlet orifice
flange is not used and cooling water flow at that
location is line sized. The outlet flange assembly orifice
is sized to provide a flow rate of approximately 1,200
gallons per minute.
A temperature switch, located near the water
discharge of one of the center JBD panels, will close if
the cooling water reaches 210°F and alert the JBD
operator by lighting a red temperature light on the
control panel. A pressure switch, located in the line
leading to the overboard discharge, will close if the
water pressure drops below the setting that determined
adequate flow rate and alert the JBD operator by
lighting a red pressure light on the control panel.
Pressure gauges, located on the control panel, provide
an indication of cooling water pressure being supplied
by the ship’s firemain. The cooling water pressure must
be maintained at a minimum of 90 psi. An additional
pressure gauge, located upstream of the discharge
orifice, is provided. A drop in pressure at this gauge
indicates blockage within the cooling water system or
inadequate
firemain
pressure.
During
JBD
certification, the normal discharge pressure and
pressure switch setting is determined.
5-5
LUBRICATION
FITTING
SWIVEL
JOINT
ASSEMBLY
SALT
WATER
HOSE
SALT WATER
DISCHARGE
OVERBOARD
VALVE
OUTLET FLANGE ASSEMBLY
WITH ORIFICE PLATE
PRESSURE
SWITCH
PRESSURE
GAUGE PIPING
DECKEDGE CONTROL
PANEL (IF USED)
AUXILIARY
CONTROL
PANEL (REF)
VALVE
PRESSURE
GAUGE
STRAINER (REF)
INLET FLANGE ASSEMBLY
WITH ORIFICE PLATE
TEMPERATURE
SWITCH
VIEW A
ABEf0505
A
Figure 5-5.—Cooling water piping installation.
