Hach AutoCAT 9000, Инструкция по эксплуатации

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Troubleshooting
Troubleshooting
Page 142
50081_Troubleshooting.fm
Data
Collection
(w/ Auto-
scaling)
Not enough
points in the
titration curve. The number of points
before the end point is too
small. • Increase the number of points before the end point
(Methods>Method library> “method“ Titr.>Auto-scaling Yes>
No. of points before EP).
Too many
points in the
titration curve. The number of points
before the end point is too
large. • Decrease the number of points before the end point
(Methods>Method library> “method“ Titr.>Auto-scaling Yes>
No. of points before EP).
The titration
curve stops
too soon after
the end point.
The fraction of points
before the end point is too
large.
• Decrease the fraction of points before the end point
(Methods>Method library> “method“ Titr.>Auto-scaling Yes>
Fraction before EP).
Data
Collection
(w/ Auto-
scaling)
The titration
curve stops
too late after
the end point.
The fraction of points
before the end point is too
small.
• Increase the fraction of points before the end point
(Methods>Method library> “method“ Titr.>Auto-scaling Yes>
Fraction before EP).
Auto-scaling is
unable to set
the current
range or the
volume
increment for
the titration.
Auto-scaling relies on the
measurement of the initial
current and an estimate of
the initial slope of the
titration curve to predict
the approximate end point
for the titration. If the
signal is very low or the
noise level is very high it
may not be able to
estimate the end point
accurately enough to set
the current range or
volume increment. • Re-run the analysis. Auto-scaling is often successful on a
second attempt.
• Turn Auto-scaling off, set the current range and volume
increment manually, and re-run the analysis.
Automated
end point
Determination
The fitted end
points are
poor.
The titration curve is very
poorly shaped or very
noisy. • Use the manual end point determination.
The ends of the titration
curve are very noisy or
distorted in some way but
the region around the end
point looks good. • Use the zoom window cursors to restrict the end point
determination to a symmetrical region about the end point.
The titration
curves are
fairly
asymmetrical.
AEPD works best when
the titration curve is
symmetrical about the
end point. Symmetrical
titration curves generally
mean that the data
collection parameters
have been fully optimized. • Adjust the data collection parameters to promote collection of
a symmetrical titration curve.
• Use the zoom window cursors to restrict the end point
determination to a symmetrical region about the end point.
The instrument
displays a
message
asking the
user to change
the data point
range.
AEPD requires that a
minimum of six points on
each side of the end point
be assigned to linear
segments for regression
analysis. If AEPD cannot
identify six points on each
side it stops. • Use the manual end point determination routine (MEPD) to
determine the end point.
• Use the zoom window cursors to select a wider symmetrical
region about the end point for analysis.
• Reduce the volume increment used to collect data. This will
give more points on each side of the end point. The other
data collection parameters may also need to be adjusted to
promote collection of a symmetrical titration curve.
Problem
Category
Symptom Probable Cause Corrective Action