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TROUBLESHOOTING & REPAIR
11.3.3. Unstable Zero and Span
Leaks in the M100E or in the external gas supply and vacuum systems are the most
common source of unstable and non-repeatable concentration readings.
•
Check for leaks in the pneumatic systems as described in Section 11.5.1. Consider
pneumatic components in the gas delivery system outside the M100E such as a
change in zero air source (ambient air leaking into zero air line or a worn-out zero
air scrubber) or a change in the span gas concentration due to zero air or ambient
air leaking into the span gas line.
•
Once the instrument passes a leak check, do a flow check (Section 11.5.2) to
make sure that the instrument is supplied with adequate sample gas.
•
Confirm the UV lamp, sample pressure and sample temperature readings are
correct and steady.
•
Verify that the sample filter element is clean and does not need to be replaced.
11.3.4. Inability to Span - No SPAN Key
In general, the M100E will not display certain keyboard choices whenever the actual
value of a parameter is outside of the expected range for that parameter. If the
calibration menu does not show a SPAN key when carrying out a span calibration, the
actual concentration must be outside of the range of the expected span gas
concentration, which can have several reasons.
•
Verify that the expected concentration is set properly to the actual span gas
concentration in the CONC sub-menu.
•
Confirm that the SO
the source with another calibrated analyzer, or by having the SO
by an independent traceable photometer.
•
Check for leaks in the pneumatic systems as described in Section 11.5.1. Leaks
can dilute the span gas and, hence, the concentration that the analyzer measures
may fall short of the expected concentration defined in the CONC sub-menu.
•
If the physical, low-level calibration has drifted (changed PMT response) or was
accidentally altered by the user, a low-level calibration may be necessary to get
the analyzer back into its proper range of expected values. One possible indicator
of this scenario is a slope or offset value that is outside of its allowed range (0.7-
1.3 for slope, -20 to 150 for offsets). See Section 11.6.3 on how to carry out a
low-level hardware calibration.
11.3.5. Inability to Zero - No ZERO Key
In general, the M100E will not display certain keyboard choices whenever the actual
value of a parameter is outside of the expected range for that parameter. If the
calibration menu does not show a ZERO key when carrying out a zero calibration, the
206
span gas source is accurate. This can be done by comparing
2
Model 100E Instruction Manual
source verified
2
045150102 Rev XB1
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Troubleshooting
