the high-water solenoid valve and the low-water
distribution header; the other line goes to the
solenoid valve. Both valves are open (energized)
control condenser. The steam stop valve is located
in the line to the distribution header; the steam
dump valve is located in the line to the condenser.
When boiler low-water level is sensed by a barton
The steam stop valve is normally closed and
gauge micro switch and the water level remains low for
requires air pressure to open; conversely, the
2 minutes, an alarm sounds on the boiler control panel.
steam dump valve is normally open and requires
This condition causes the Leslie pilot controller to route
air pressure to close.
air pressure to fully open the feedwater control valve.
When boiler high-water level is sensed by the barton gauge micro
switch, a signal is sent to a leslie pilot controller. This causes the
Steam Stop Valve
control air pressure being supplied to the feedwater control valve
The steam stop valve is either open or shut.
actuator to be blocked and vented to the atmosphere. If low-low water
It is actuated by control air from the ship's
level is sensed by the barton gauge, an alarm signal is generated, and the
service air system (SSAS). A solenoid valve, when
energized, admits control air to the steam stop
low-low water, and high water level indicators mounted on the
valve actuator, opening the valve. De-energizing
front panel section. The PACC only has a summary fault alarm for
the solenoid valve blocks the control air and vents
the actuator to the atmosphere, causing the stop
valve to close.
Steam Dump Valve
Some additional components that support the
The steam dump valve is modulated to
boiler operation are the chemical treatment tank,
control the amount of steam diverted to the
the blowdown valves, the soot blower system, and
control condenser. The steam pressure controller
the condensate collecting system.
senses steam pressure and regulates control air to
position the dump valve. An increase of steam
Chemical Treatment Tank
pressure causes a decrease of control air pressure
and the dump valve tends to open. This diverts
The chemical treatment tank is provided for
steam to the control condenser, thus reducing
chemical treatment of the boiler feedwater.
steam pressure. A decrease of steam pressure
Parameters for boiler-water chemistry are
causes an increase of control air pressure and the
provided in Naval Ships' Technical Manual,
dump valve tends to close; this increases steam
pressure. The steam dump valve can also be
Some ships have a continuous chemical
injection system installed. It consists of a chemical
injection tank that is filled with chemicals that are
FEEDWATER CONTROL VALVE
injected into the system by a proportioning pump.
The feedwater control valve is a normally
closed valve that requires air pressure to open.
Valve control is automatic; a handwheel is
Blowdown of the steam separator and the
provided for manual operation if a failure occurs.
inlet and outlet headers is used for the removal
The feedwater control valve is modulated by
of sludge and sediment. The blowdown is
the leslie pilot controller to regulate the
provided for through an outlet on the bottom of
water level in the boiler (steam separator/
the separator and through valves at the low point
reservoir). The leslie pilot controller senses
of each header. The blowdown valves are
the water level in the steam separator/reservoir
manually operated. These valves and the
as a differential pressure and provides a variable
associated piping are also used to drain the boiler.
air pressure to the feedwater control valve
actuator to control flow. When the water level
rises, control air pressure reduces and the feed-
water valve tends to close. When the water level
The soot blowers consist of four stationary
drops, control air pressure rises and the valve
steam lances positioned vertically between the
coils, 90° apart, and are controlled by individual
tends to open.
valves. Steam is discharged from holes in the lance
The control air line to the feedwater control
valve has two solenoid-actuated valves. They are
arranged so that the steam covers all sides of the