The isolation shall be such that an open or short circuit in the
related equipment shall not affect other control systems.
2.5
HEATING PLANT PANELS AND INSTRUMENTS
Mercury shall not be used in thermometers.
2.5.1
HTW Generator Instrument and Control Panel
The HTW generator instrument and control panel shall be sized to contain
all controls, instruments, gauges, and meters. The panel shall be
free-standing with faceplate of not less than 4.8 mm 3/16 inch steel,
properly reinforced, and shall be finished with the manufacturer's standard
finish coating. The units shall be mounted flush on the panel as far as
practicable. The back of the panel shall be enclosed with sheet metal and
with adequate removable access panels or doors for maintenance and removal
of any unit without interfering with other units. Proper latching
equipment and hardware shall be provided. Each recorder, indicator, and
control unit shall be identified with engraved metal or laminated plastic
nameplates securely fastened to the panel. The panel shall have
continuous, rapid-start, fluorescent light fixtures mounted with reflectors
providing suitable shielding to illuminate all controls, instruments,
gauges, and meters. All field piping connections shall terminate in one
bulkhead-mounted manifold located to conform with the installation
requirements of the system. All field electrical wiring shall terminate in
a suitably mounted color-coded terminal strip so located as to conform with
the installation requirements of the system. If a pneumatic control system
is provided, the panel shall include duplex air supply filter and regulator
set, mounted on the rear of the panel with properly identified pneumatic
terminal blocks and low-point drain. No high-pressure lines will be
allowed to enter the panel. The control equipment shall include the
necessary operating switches, indicating lights, gauges, alarms, the
combustion control system, and the generator and fuel safety interlock
systems. If the package type boiler burner units with integral controls
are furnished, the control equipment for each boiler may be mounted on a
separate free-standing panel in accordance with the requirements above for
instrument and control panel. Controllers and indicators specified or
required shall be panel-mounted and tested at the factory complete with
relays, transformers, switches, wiring, valves, and piping. All wiring and
piping within the panel shall be color-coded or otherwise identified.
2.5.2
Indicators
Indicators shall be flush mounted with a vertical scale from 100 to 150 mm
4 to 6 inch length. Indicators may be either electronic or pneumatic with
zero adjustments, receiving standard signals from locally mounted
transmitters. Scales shall be in engineering units with an accuracy of
plus or minus 1 percent.
2.5.3
Recorders
Recorders shall be servo mechanism type, multiple pen type. [Circular]
[Strip chart] type shall be provided. Minimum chart width is 100 mm 4
inches. Accuracy shall be plus or minus 1/2 percent. Each pen shall have
a separate scale calibrated in engineering units. Chart drive shall be 120
volts ac. One year's supply of chart paper shall be provided.
SECTION 15555A
Page 40
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