on the control panel that will provide for selecting either automatic
control or manual control and also will provide for manual operation.
Manual controls shall be arranged to allow any one or more of the functions
of the control system to be controlled manually while the other functions
remain on automatic control. The manual control station shall be complete
with all necessary indicators to facilitate changing from automatic control
to manual control and vice versa. Controllers mounted on the instrument
panel shall indicate and control measurement in the areas shown, and shall
have a manual adjustment on the front of the instrument. Controllers shall
be installed complete with wiring or piping between the controller,
transmitter, and the final control device.
2.9.2
Equipment
Control equipment and instruments shall include fan controls, time clocks,
relays, operating switches, indicating lights, gauges, motor starters,
fuses, alarms, and circuit elements of the control system, and other
controls and instruments necessary for unit operation. Control system
shall be in accordance with FM P7825a and FM P7825b. Operating controls
and instruments shall be mounted on one or more free-standing control
panels conveniently located and placed so that operating personnel may
effectively monitor boiler operations but not in a position that would
interfere with those operations. Indicating and recording instruments will
be provided for pressure, flow of air and liquids, and alarm circuitry.
Automatic-control circuit systems and manual switches shall be interlocked
to prevent hazardous conditions or the discharge of excessive amounts of
air pollutants.
2.9.3
Boiler System Operation
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NOTE: If the fuel being burned contains any
significant pollutants, some states may not allow
the flue gases to be vented to the atmosphere
without going through an air pollution control
device.
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When steam is demanded, gases shall be directed through the boiler. As
long as maximum energy is required, this shall be the mode of operation.
If less than full energy production is required, gas flow shall be
modulated to reduce steam production by the boiler. Specified steam
pressure shall be maintained within plus or minus 1 pound by means of a
pressurestat and a boiler-draft regulator. The pressurestat with necessary
relays shall stop and start the flow of gases by means of the induced draft
fan so as to maintain the desired steam pressure.
2.9.4
Damper Control
Power units for the movement of dampers shall be sized to operate the
device to be positioned, and shall be mounted so that a rigid mechanical
connection to the device being operated can be used. Units shall
automatically close in the event of failure of the operating medium.
Manual operation of the controller shall not necessitate disconnecting the
linkages during power failure or other emergency. Position switches shall
be included on fuel and air-drive units for interlock with safety systems.
Retransmitting devices shall be placed on all power units for remote
indication on the control panel of the position of the mechanism at any
time. If electric operators are utilized, gear trains on the units shall
SECTION 15846A
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