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Teledyne API - T100 UV Fluorescence SO2 Analyzer Troubleshooting & Service
247
12.4.5. INABILITY TO ZERO - NO ZERO BUTTON
In general, the T100 will not display certain control buttons 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 SO
2
-free air. Check any zero air scrubber for performance and replacement
(refer to Section 11.3.3).
Check to ensure that there is no ambien
t air leaking into the zero air line. Check for
leaks in the pneumatic systems as described in Section 11.3.6.
12.4.6. NON-LINEAR RESPONSE
The T100 was factory calibrated 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 12.6.
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.
The sample delivery system may be contaminated. Check for dirt in the sample lines
or sample chamber.
Calibration gas source may be contaminated.
Dilution air contains sample or span gas.
Sample inlet may be contaminated with SO
2
exhaust from this or other analyzers.
Verify proper venting of the analyzer’s exhaust.
Span gas overflow is not properly vented and creates a back-pressure on the sample
inlet port. Also, if the span gas is not vented at all and does not supply enough
sample gas, the analyzer may be evacuating the sample line. Ensure to create and
properly vent excess span gas.
If the instrument is equipped with an internal IZS valve option and the SO
2
span
value is continuously trending downward, the IZS permeation tube may require
replacement.
06807C DCN6650