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4.0 MAINTENANCE SCHEDULE The maintenance requirements of the T201 are the same as a standard
T200 NOx analyzer but with additional maintenance items (Table 4-1).
Please refer to Section 13 in the T200 Operator Manual for the T200
maintenance schedule and for maintenance and repair procedures.
The T201 requires the following additional maintenance items.
Table 4-1. Preventative Maintenance Schedule
Item Maintenance Interval Reference Section
NO2 molybdenum converter Test every three months Section 8.2.3 T200 Manual
M501 NH3 Converter Test every three months
Replace annually or as necessary Section 4.1 of this manual
Reaction Cell Clean annually or as necessary Section 9.3.9 T200 Manual
AutoZero flow check Quarterly as needed Section 4.4 of this manual.
4.1 M501 NH3 MAINTENANCE
The M501 NH3 external converter is operated at 825 ºCelsius. Because of
this the stainless steel ¼” tube internal to the converter slowly oxidizes
and may require replacement. Over time the converter’s efficiency will
degrade, due to aging of the internal catalyst. This is characterized by a
CONV value on the TNx channel of < 0.8 or > 1.2, despite the converter
being at temperature. The efficiency of the converter should be checked
quarterly. The converter should be cleaned out on a yearly basis by
removing the outer tube and shaking the fine dust particles from both the
outer and inner tubes. This is also a good time to replace the catalyst
screen, if necessary.
The following procedure describes how to disassemble and replace
converter parts. The various parts in the converter become delicate and
brittle after prolonged exposure to high temperatures. It is therefore a
good idea to have a complete set of replacement parts on hand before
starting, as listed in Table 4-2.