05206H DCN5910 35
4.0 MAINTENANCE SCHEDULE
The maintenance requirements of the M201E are the same as a standard M200E
NO
x
analyzer but with additional maintenance items (Table 4-1). Please refer to
Section 13 in the M200E Operator Manual for the M200E maintenance schedule
and for maintenance and repair procedures.
The M201E requires the following additional maintenance items.
Table 4-1. Preventative Maintenance Schedule
Item Maintenance Interval Reference Section
NO
2
molybdenum converter
M501 NH
3
Converter
Test Every Three Months
Section 8.2.3 M200E Manual
Section 4.1of this manual.
Reaction Cell Clean annually or as necessary Section 9.3.9 M200E Manual
AutoZero flow check Quarterly as needed Section 4.4 of this manual.
4.1 M501 NH
3
MAINTENANCE
The M501 NH
3
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.
