Figure 1-8.Type III liquid cooling system.
taken from the firemain through a duplex strainer and a
flow regulator (orifice plate) to and through the heat
exchanger. It is then discharged overboard. The
connection to the firemain is permanent.
The ships fire pump, not shown in figure 1-7, is
used to pump seawater into the firemain. The fire pump
is similar in design to the previously mentioned seawater
circulating pump, except it has a much larger capacity.
Another means of getting seawater as a primary
coolant is by an emergency connection (figs. 1-6 and
1-7). This method is used if the normal seawater supply
is lost. The connection is usually by means of a 1-inch
fire hose. The emergency supply comes from an
alternate portion of the ships firemain or a portable
pump rigged by the ships damage control party. The
portable emergency hose is normally stored in the liquid
coolant machinery room.
Note: Seawater systems are referred to as
open-looped or one-pass because the seawater flows
through the system only once.
In figures 1-7 and 1-8, chilled water is taken from
the supply main of the air-conditioning, chilled-water
systems. The chilled water is used as a backup source
of cooling water for the primary cooling system shown
in figure 1-7, and as a normal and backup source in the
system shown in figure 1-8. The chilled water flows
through the tubes of the heat exchanger (chilled water
to distilled water), a flow regulator, and back to the
chilled-water system. A temperature regulating valve at
the inlet of the heat exchanger regulates the flow of
chilled water through the heat exchanger to maintain the
required water temperature in the secondary system
The ships air-conditioning,
chilled-water circulating pump is used to pump the
chilled water through the heat exchanger. The
chilled- water system is a closed-loop water system
because the water is recirculated. It must be kept tight
and free from leaks to assure satisfactory operation.
SECONDARY COOLING SYSTEM
The secondary cooling system is designed to
transfer heat from the electronic equipment being
cooled to the primary cooling system. This system is
usually comprised of a distilled- water circulating pump,
a compression or gravity-feed expansion tank, the