Emerson Rosemount Xi, Справочное руководство

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6 Maintenance and service
6.1 Overview
This section identifies the calibration methods available and provides the procedures to
maintain and service the Rosemount Xi.
WARNING
Install all protective equipment covers and safety ground leads after equipment repair
or service. Failure to install covers and ground leads could result in serious injury or
death.
6.2 Maintenance intervals
The maintenance interval required is quite variable, depending on the type of service the
analyzer is placed into. The zirconium oxide sensing cell is non-depleting and has no
specific shelf life or a defined life in flue gas operation. The cell of a probe that is mounted
inside a boiler that is burning natural gas may shift very little over several years. Acidic
compounds are the main aggressors to the sensing cell, typically SO
2
resulting from sulfur
contained in coal and heavy oil fuels and also HCl from the combustion of plastics in
municipal incinerators and in industrial thermal oxidizers. Sensing cells may experience
significant degradation and signal shift in this type of service, particularly if the operating
levels of O
2
are very low (below 1% O
2
).
A calibration check is generally recommended on a quarterly basis (every 3 months) by
flowing bottled gas to the probe. (Make sure that the operations personnel are notified
when doing this and also make sure that the O
2
control loop is placed in manual mode). If
the probe readings vary significantly from the bottle values, then a formal calibration
should be conducted as noted in
Startup and operation .
The Rosemount Xi offers a calibration recommended diagnostic that indicates when the
probe needs to be calibrated.
Combustion processes that have a high level of ash or other particulate content will cause
the diffusion element on the end of the probe to plug off. A badly plugged diffuser causes
a slower speed of response to changing O
2
levels in the process. This can usually be seen
on the recorded trends in the control room.
When performing a calibration check or actual calibration, the calibration flow meter may
read lower if the diffuser is badly plugged. (Never increase the flow rate back up, however,
as this can cause a shifted calibration. Adjust the calibration flow rate only when a new
diffuser is installed). Always record the response time back to the process after the
calibration gases are removed.
During plant outages, conduct a visual inspection of the probe, paying particular attention
to condensed components. To reduce or eliminate condensation, insulate the probe
installation, including the probe mount, flange, and dual blue housings.
Reference Manual Maintenance and service
00809-0100-4889 October 2022
Emerson.com/Rosemount 59