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M400E Ozone Analyzer Operator’s Manual General Troubleshooting & Repair of the M400E Analyzer
13.4.1.3. High Flow
The most common cause of high flow is a leak in the sample flow control assembly or between there and the
pump. If no leaks or loose connections are found in the fittings or the gas line between the orifice and the pump,
rebuild the sample flow control assembly as described in Section 13.10.1 .
13.4.1.4. Actual Flow Does Not Match Displayed Flow
If the actual flow measured does not match the displayed flow, but is within the limits of 720-880 cc/min, adjust
the calibration of the flow measurement as described in Section 13.10.1.
13.4.1.5. Sample Pump
The sample pump should start immediately after the front panel power switch is turned ON. If it does not, refer
to Section 13.7.1.
13.5. CALIBRATION PROBLEMS
13.5.1. MIS-CALIBRATED
There are several symptoms that can be caused by the analyzer being mis-calibrated. This condition is
indicated by out of range
SLOPEs and OFFSETs as displayed through the test functions and is frequently
caused by the following:
Contaminated span gas. This can cause a large error in the slope and a small error in the offset. Span
gas contaminated with a major interferent such as Mercury Vapor, will cause the analyzer to be calibrated
to the wrong value.
Also could be caused if the span gas concentration entered into the analyzer during the calibration
procedure is not the precise concentration value of the gas used.
Dilution calibrator not set up correctly or is malfunctioning. This will also cause the slope, but not the zero
to be incorrect. Again, the analyzer is being calibrated to the wrong value.
Too many analyzers on the manifold. This can cause either a slope or offset error because ambient gas
with its pollutants will dilute the zero or span gas.
Contaminated zero gas. This can cause either a positive or negative offset and will indirectly affect the
slope. If contaminated with O
3
it will cause a positive offset.
13.5.2. NON-REPEATABLE ZERO AND SPAN
As stated earlier, leaks both in the M400E and in the external system are a common source of unstable and non-
repeatable readings.
Check for leaks in the pneumatic systems as described in Section 12.3.5. Don’t forget to consider
pneum
atic components in the gas delivery system outside the M400E. Such as:
A change in zero air source such as ambient air leaking into zero air line, 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 (see Section 12.3.5) to make sure adequate
sampl
e is being delivered to the optical bench assembly.
04315 Rev. C1 243