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Instruction Manual
IM-106-5500, Original Issue
August 2005
CCO 5500
1-4
Signal Processor Unit The signal processor unit is housed in a fully-sealed cast-aluminum
enclosure. It houses the microprocessor to monitor the data from the receiver
and produces a 4-20 mA output signal for gas levels within the flue.
A non-volatile RAM section - requiring no battery back-up - enables all of its
operation data to be retained during a power down condition. The instrument
can resume operation immediately when power is restored without having to
be recalibrated.
All operation data is entered via a surface-mounted keypad. A 32-character
LCD provides the operator with measurement details and diagnostic
information.
Inputs are available to receive the 4-20 mA outputs of normalizing
measurement transducers - O
2
, temperature and pressure, if required. This
data can also be entered via the keypad or via the serial data port.
A serial communication facility within the processor allows the instrument to
communicate with other Rosemount analyzers and a central data logging unit.
Power Supply Unit The power supply unit is housed in a fully-sealed cast-aluminium enclosure
and contains the power supplies for the instrument. A switched mode power
supply is utilized to provide an extremely stable power source, able to cope
with large fluctuations in the supply voltage. The contact outputs are also
taken from this unit - data valid and high gas alarm.
Air Purge The air purge unit has its own integral adjustable mount and provides the
interface between the site mounting flange and the transmitter and receiver
units. The purge is designed to provide a steady laminar flow of air away from
the instrument lens, preventing optical contamination.
A supply of air to the purge is essential.
Isolating Valves Isolating valves, if required, may be attached between the air purges and the
duct. These will allow protection for personnel servicing instruments on high
pressure ducts.
PRINCIPLES AND
MODES OF OPERATION
Calculation of Gas
Concentration
Gas levels are determined by measuring the absorption of infrared radiation,
transmitted through the flue gas, in a wave band sensitive to absorption by the
measurement gas. CCO 5500 monitors have two detectors; one measures
the radiation directly to provide a live output, sensitive to the measurement
gas, while a second detector measures the radiation after passing through a
gas cell filled with pure reference gas (CO), to provide a reference
measurement, completely unaffected by the measurement gas.