Teledyne T101, Operation Manual, Page: 227 / 375

Teledyne ML - T101 Operation Manual Troubleshooting & Service
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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 H
2
S span gas source is accurate. This can be done by
comparing the source with another calibrated analyzer, or by having the
H
2
S source verified by an independent traceable photometer.
•
Check for leaks in the pneumatic systems as described in Section 9.5.1.
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 9.6.4 on how to carry out a low-level hardware
calibration.
9.3.5. INABILITY TO ZERO - NO ZERO BUTTON
In general, the T101 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 button 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 H
2
S and SO
2
free air. Check the zero air
scrubber for performance. It may need to be replaced (Section 8.3.3).
•
Check to make sure that there is no ambient air leaking into the zero air
line. Check for leaks in the pneumatic systems as described in Section
9.5.
9.3.6. NON-LINEAR RESPONSE
The T101 was factory calibrated to a high level of H
2
S and should be linear to within
1% of full scale. Common causes for non-linearity are
• Leaks in the pneumatic system. Leaks can add a constant of ambient air,
zero air or span gas to the current sample gas stream, which may be
changing in concentrations as the linearity test is performed. Check for
leaks as described in Section 9.5.
• The calibration device is in error. Check flow rates and concentrations,
particularly when using low concentrations. If a mass flow calibrator is
used and the flow is less than 10% of the full scale flow on either flow
controller, you may need to purchase lower concentration standards.
• The standard gases may be mislabeled as to type or concentration.
Labeled concentrations may be outside the certified tolerance.