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DEFOR · Supplementary Operating Instructions · 8013029 V2.0 · © SICK AG
Functions in SOPAS ET
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4.3.4
Drift limit values
Purpose
Analyzer module drifts are caused, for example, by contamination, mechanical changes or
aging effects. The total drift (i.e. the deviation from original state) increases gradually. It is
not practical to keep compensating an ever increasing total drift through computation.
Inspect and reset the Analyzer module when total drift has become very large.
Drift limit values monitor total drift automatically. These also protect against erroneous
adjustments.
Functionality
After every adjustment, an Analyzer module compares the calculated total drift with the
drift limit value. Drift limit value violation is reported in two stages:
●
Status “M” (Maintenance request) is activated when the total drift reaches 100 … 120%
of the drift limit value.
●
Status “F” (Failure) is activated when the total drift reaches more than 120% of the drift
limit value.
●
When an adjustment procedure shows that a calculated drift has reached more than
150% of the drift limit value, the result from this adjustment procedure is ignored and
the previous adjustment remains valid.
4.3.5
Deleting adjustment results
The “Delete results” function deletes all determined drift values of a measuring compo-
nent. Drift limit values then refer to new drift values.
The data of the previous adjustment which was performed before are then no longer dis-
played. Test gas settings (e. g. nominal value) are not changed.
●
The drift limit values are set in the factory (standard value: 10%).
●
A Service function is available to reset all drift values to “0” (Drift reset).
This is useful after Analyzer module maintenance when this has estab-
lished a new original state.
CAUTION:
Risk of incorrect adjustment
If very large drift values are displayed after a manual adjustment procedure
(
→
Operating Instructions “Basic Control Unit (BCU)”), a test gas used probably
did not match the relevant test gas setting or gas feed was interrupted – and
the adjustment result was still accepted.
▸
Do not delete incorrect adjustment results, but repeat the adjustment care-
fully.
▸
Do not use the deletion of adjustment results to nullify large drift values
caused by extensive physical changes of an Analyzer module. Instead,
clean the Analyzer module or perform an adjustment.
[1]
▸
After an Analyzer module has been cleaned, altered or exchanged:
Delete the relevant adjustment results and perform an adjustment.
[1] By the manufacturer's Customer Service or authorized skilled persons with appropriate training.