be oil immersed.
2.9.5
Draft Fan Control
Induced draft centrifugal fans shall have outlet dampers [and variable
speed control]. [Axial propeller fans shall have variable propeller pitch
control.] Means shall be provided for operating the induced draft fan for
15 minutes after the combustion equipment has ceased operation.
2.9.6
Soot Blower
All controls, lights, switches, and indicators provided for operation of
soot blower shall be mounted on the control cabinet.
2.9.7
Boiler Limit Controls
Limit controls and interlock switches shall conform to UL 353.
2.9.7.1
Low-Water Cutoffs
Two low-water cutoffs shall be provided to prevent startup and to shut down
the combustion equipment if the boiler water level is below the preset safe
level. Primary interlock may be automatic or manual reset type. Secondary
interlock shall be the manual reset type.
2.9.7.2
High-Pressure Limit Switch
A high-pressure limit switch shall be provided to shut down the combustion
equipment when steam pressure exceeds the preset safe limit. This
equipment shall be additional to the operating controls.
2.9.7.3
Draft Loss Interlock
A draft loss interlock and an airflow switch or a suction switch shall be
provided to prevent startup and to shut down or bypass the combustion
equipment when air is inadequate to safely support combustion. Limit and
operating controls shall be provided for operation on a two-wire grounded
branch circuit.
2.9.8
Instrument Control Panel
Panel shall be a NEMA ICS 6 Type 4 unit prewired, of steel, weathertight,
and conforming to UL 50. Unless enclosed in a booth or separate room, the
panel shall also be constructed to protect the instruments and controls
from dust. The boiler control panel shall be located next to the control
panel for the combustion equipment, or one panel may be used for both.
Wiring of all instrument connectors and cable termination connectors shall
be done in the factory by the instrumentation fabricator. All controls,
instruments, and other equipment shall be flush mounted at the factory and
be assembly-tested before shipment. A lock and two keys shall be
furnished. All controls and instruments shall be identified with
nameplates. [A thermostatically controlled heater to prevent condensation
shall be provided.]
2.9.8.1
Panel Details
Instrument and control panel shall be sized to contain all controls,
instruments, gauges, and meters. Panels shall be freestanding with a
faceplate of not less than 7 mm 3/16 inch steel, properly reinforced, and
SECTION 15846A
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