boiler master controller[s].
b.
Boiler master controller shall increase or decrease firing rate
based on comparison to setpoint.
c.
control modes.
d.
Combustion controls shall be fully integrated with flame safeguard
system to assure low-fire startup and complete purge regardless of
boiler master output signal.
e.
Combustion control strategy shall be single point positioning with
oxygen trim.
f.
Boiler firing rate shall be controlled by actuating burner
jackshaft drive motor to move jackshaft that mechanically links
fuel and combustion airflow.
g.
Boiler oxygen trim shall be accomplished by modulating combustion
air damper to alter fuel-air ratio based on input from oxygen
analyzer.
h.
Control loops shall include manual-automatic stations to provide
for control of system. Each manual-automatic station shall
contain a built in indicator to graphically depict variable being
controlled.
i.
other boilers. Common electrical signals shall be electrically
isolated in each boiler section.
2.5.5
Enclosures
a.
Free-standing or boiler-mounted factory-assembled steel enclosure
with indicators, control switches, flame safeguard cabinet and
indicating lights on cabinet front and relays and other components
mounted on interior subbases shall be provided for each boiler.
For multiple boiler installations, the boiler No. 1 panel shall
contain controls common to all boilers. Enclosure shall have
locking doors and shall comply with NEMA ICS 6.
b.
Enclosure shall be NEMA 12, 11 gage steel, all welded construction
with minimum radius corners, stiffened as required and framed with
angles. Door shall be constructed of 14 gage steel with
key-locking vault handle and three (3)point latches. Doors shall
be fully gasketed.
c.
Metal surfaces shall be cleaned, phosphatized, primed and
finished. Interior shall be glass white enamel. Exterior shall
be gray texture polyurethane enamel to provide resistance to fuel
oil, solvents and abrasion. Engraved plastic laminated nameplates
shall be provided for devices on the front of the cabinet except
where devices themselves are provided with a service engraving.
Nameplates shall have white letters on a black background and be
minimum 6.5 mm 0.25 inch height, mounted with screws or epoxy or
secured by pilot light or switch. Equipment title and
identification number shall be listed. Abbreviations are not
SECTION 15561A
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