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Troubleshooting & Repair Teledyne API M100E Analyzer Operation Manual
266
12.4.6. NON-LINEAR RESPONSE
The M100E 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 cali
bration 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.
12.4.7. DISCREPANCY BETWEEN ANALOG OUTPUT AND DISPLAY
If the concentration reported through the analog outputs does not agree with the value reported on the front
panel, you may need to re-calibrate the analog outputs. This becomes more likely when using a low
concentration or low analog output range. Analog outputs running at 0.1 V full scale should always be calibrated
manually. Refer to Section 6.9.4.3 for a detailed description of this procedure.
04515F DCN6048