c.
HTW generator (each) - safety shutdown
d.
Fuel (to suit firing system):
Low
fuel oil header pressure
Low
fuel oil storage level
Low
stoker hopper level
Low
coal bunker level
e.
Air:
Low service air pressure
Low instrument air pressure if pneumatic controls are used
f.
Distribution zones (each) - low return pressure
The annunciator shall be provided with lamp test and acknowledge push
buttons. The operational sequence shall be as follows:
Condition normal
-
Light off, horn off
Alarm
-
Light flashing, horn on
Alarm acknowledged
-
Light on, horn off
Return to normal
-
Light off, horn off
The system shall be provided with devices to actuate the annunciator from
the above sources, unless otherwise specified.
2.5.15.5
Liquid Level Control Stations
Liquid level control stations shall be provided at the expansion tank and
dump tank, and shall include adequate detection, sensing, and actuating
devices to provide signals for the annunciator system and to control the
overflow system. The levels for carrying out the above functions shall be
as indicated.
a.
Expansion Tank Overflow Controller: Overflow control system from
the expansion tank shall be provided. The expansion tank shall
overflow on control signal from the control station specified
above which shall actuate a motorized normally-closed valve
allowing water to relieve to the dump tank.
b.
Dump Tank Overflow Controller: Overflow control system from the
dump tank shall be provided. The dump tank shall overflow on
control signal from the controller which shall actuate a motorized
normally-closed valve allowing water to relieve to the blowdown
tank.
2.5.15.6
Distribution Zones Control Station
A control station for distribution zones valve control shall be provided
with one manual valve control for each zone. The instrument shall indicate
the position of the valve operator and shall provide remote control and
adjustment of the valve. The controlled valve shall be a motorized gate
valve in the distribution zone supply line for emergency shutoff and flow
modulation. The motorization of the valve shall be such that any partial
SECTION 15555A
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