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089770000 Rev 05
Teledyne API N500 CAPS NO
X
Analyzer with NumaView™ Software
77
•
The technician can view the raw, unprocessed signal level of the analyzer’s critical
inputs and outputs.
•
Many of the components and functions that are normally under algorithmic control
of the CPU can be manually exercised.
•
The technician can directly control the signal level Analog and Digital Output
signals.
This allows the technician to observe systematically the effect of directly controlling
these signals on the operation of the analyzer. Use the Utilities>Diagnostics menu to
view the raw voltage of an input signal or the Setup menu to control the state of an output
voltage or control signal.
CALIBRATION PROBLEMS
This section describes possible causes of calibration problems.
N
EGATIVE
C
ONCENTRATIONS
Negative concentration values can be caused by calibration error: If the zero air were
contaminated, and the analyzer was calibrated at “zero”, the analyzer may report a
negative value when measuring air that contains little or no NO
x
.
A
BSENCE OF
A
NALYZER
R
ESPONSE TO
S
AMPLE
G
AS
If the instrument shows no response (display value is near zero) even though sample gas
is supplied properly and the instrument seems to perform correctly
:
1. Confirm the lack of response by supplying NO
2
span gas of about 80% of the
range value to the analyzer.
2. Check the sample pressure and cell pressure for proper value.
3. Check for disconnected cables to the sensor module.
4. If delivering NO gas, check that Lamp Current is in 7-10 mA.
U
NSTABLE
Z
ERO AND
S
PAN
Leaks in the instrument or in the external gas supply and vacuum systems are the most
common source of unstable and non-repeatable concentration readings.
1. Check for leaks in the pneumatic systems as described in Section 5.6.5.
2. Consider pneumatic components in the gas delivery system outside the analyzer
such as a change in zero air source (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.
3. Once the instrument passes a leak check, do a flow check (this chapter) to ensure
that the instrument is supplied with adequate sample and ozone air.
4. Confirm the sample pressure, sample temperature, and sample flow readings are
correct and steady.
5. Verify that the sample filter element is clean and does not need to be replaced.
Summary of Contents for N500
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