the alternate pump automatically starts running. A
gauge board within the pump room contains gauges for
pump suction and discharge pressure and for measuring
the water pressure at the connectors (elbow pressure).
WATER-BRAKE WATER SUPPLY PIPING
The suction inlets of the pumps (fig. 4-29) are
submerged in the water-brake tanks. The pump
flow-limiting orifice plate, are tied together and
connected via flexible hoses to strainer flanges at the
bottom of the water supply pipes. Hoses and rigid
piping connect the pressure switches to the supply
pipes. A pump suction gauge and a pump discharge
gauge are located on the gauge panel for each pump.
These are in addition to the gauges for the pressure
sensing switches. The suction side of the pump consists
of an inlet with a gate type shutoff valve, a gauge valve,
and a Macomb strainer immediately ahead of the pump
inlet. A petcock for venting is mounted at the top of the
strainer. The discharge side of each pump includes a
flow limiting orifice plate, a check valve, and a gate
type shutoff valve. Two discharge lines merge into a
High-pressure, flexible hoses lead to and connect to the
brake cylinder water supply connectors, which are
attached to the water-brake cylinders. A drain valve for
the water-brake tank leads to an overboard discharge.
Fresh water from the ship's system is added to the tank
via fill and shutoff valves in the water-brake pump
Two pressure switches are connected to the piping
leading from the pumps to the brake cylinders (see fig.
4-29). They usually are installed on the bulkhead
adjacent to the tank. The switches are electrically tied
in with the main control console/ICCS/CCP to prevent
operation in case the pressure falls below normal. Water
pressure keeps the switch contacts closed, thus
completing a circuit. Should the pressure fall below
normal, either one or both of the switches will drop
open, breaking the circuit. There are also two pressure
gauges in the lines to give a visual indication of the
pressure, commonly referred to as "elbow pressure."
TO CHARGE PANEL
Figure 4-29.Water-brake piping and pressure switch installation.