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Teledyne API M100E Analyzer Operation Manual Troubleshooting & Repair
265
12.4.3. 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 10.3.6. Consider pneumatic
compone
nts 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, perform a flow check (refer to Section 10.3.7) to ensure that
the instru
men
t 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.
12.4.4. 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
2
span gas source is accurate.
If you are using bottle calibration gas and have recently changed bottles, bottle to bottle variation may be
the cause.
Check for leaks in the pneumatic systems as described in Section 12.6.1. Leaks can dilute the span gas
and, hence, the co
ncentration 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). Refer to Section 12.7.2.8 on how to carry out a
low-l
e
vel hardware calibration.
12.4.5. 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 actual gas concentration must be significantly different from the actual zero
point (as per last calibration), which can have several reasons.
Confirm that there is a good source of zero air. If the IZS option is installed, compare the zero reading
from the IZS zero air source to an external zero air source using SO
2
-free air. Check any zero air
scrubber for performance and replacement (refer to Section 10.3.3).
Che
ck to ensure that there is no ambient air leaking into the zero air line. Check for leaks in the
pneumatic systems as described in Section 10.3.6.
04515F DCN6048