Section 4
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16116Maintenance.fm
Reading Drifts After Span Calibration
into the flow cell or flow stream and allow 30 minutes before starting the span
calibration.
d.
Re-zero and re-span the instrument, allowing at least 30 minutes of
stabilization time.
4.4 Reading Drifts After Span Calibration
This condition may be caused when the instrument is span calibrated before it
has settled to its final reading. Because the final reading is significantly
affected by temperature at low chlorine levels, allow 30 minutes for the probe
thermistor to match the sample stream temperature and re-span the
instrument. Remember that the instrument will not span if the displayed
concentration is below 0.02 ppm.
If the probe was immersed in deionized water for several hours prior to the
zero and this span calibration, allow the display to stabilize for 60 minutes with
the probe immersed in the concentration before span calibrating.
4.5 Calibration Error Messages
During calibration, the instrument may scroll one of the error messages listed
below. Follow the directions listed below each message to help isolate and
correct the problem.
4.6 Calibrating with a Simulated Input
This procedure can be used to verify that the monitor is capable of calibrating
a probe and should be performed only when a problem with the monitor is
suspected.
Note:
During this procedure the factory default parameters will be restored. Prior to
performing this procedure, document the instrument's parameter setting so that
they may restored later.
4.6.1 Equipment Required
•
Voltage source isolated from earth ground.
•
Precision Voltmeter, Fluke 77 or equivalent.
Table 8
Error Message
Alarm Condition/Cause of Error
Solution
Probe fault detected, cal aborted.
TEMP SIGNAL HIGH
Refer to the “*Check Message”
paragraphs in this chapter for more
details about the cause of these
problems.
TEMP SIGNAL LOW
Unstable input, cal aborted
Indicates that the probe input signal is
too unstable to be reliable as a
calibration data point.
If the probe has just been rebuilt, verify
that the proper stabilization period has
been observed.
Increase the damping parameter and
attempt the calibration again.
Although not recommended, you may
bypass the stability check by activating
the
E
icon.
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