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Emerson Process Management GmbH & Co. OHG7-8
X-STREAM XE
Instruction Manual
HASXEE-IM-HS
10/2010
7.4.1 Preparing Calibrations
Example:
Measuring range: 0 ... 50 %
Zero gas: 0 %
Span gas: 50 %
Tolerance limits: 20.0 % (see gure above)
Situation:
Due to a fault zero gas is supplied to carry
out a span calibration, instead of span gas.
Deviat. toler. check disabled (Off):
The analyzer calibrates the span with the
wrong gas resulting in an analyzer out of
tune.
Deviat. toler. check enabled (On):
Starting a span calibration with zero gas
connected instead of span gas, the analyzer
gives an error message and stops calibrating
because the measured (expected span gas)
value differs more than the value specied,
from the upper measuring range limit.
Note!
Unacknowledged maintenance requests are
stored even if the instrument is switched off
and on again!
In addition: If, for example, a calibration was
aborted because of a tolerance check, the
maintenance request is active. If the operator
does not acknowledge the request and per-
forms a new calibration, now with disabled
tolerance check, the earlier maintenance re-
quest is stored and re-activated again, when
the tolerance check is enabled somewhere
in the future!
Next enter TOLERANCES:
By default the option 'Deviat.toler.' (deviation
tolerance check) is disabled (Off).
With deviation tolerance check enabled (On),
during calibration the analyzer compares the
currently measured concentration to the ex-
pected value, as setup in the GASES menu.
If the measured concentration differs from the
expected values by more than the percentage
of measuring range, given in the menu lines
2&3, calibration is aborted and a maintenance
request alarm is set (symbol, message and
optional relay output).
Resetting the alarm requires to perform a valid
calibration, or to conrm it within CONTROL
- ACKNOWLEDGEMENTS.
So, tolerance check helps avoiding calibrating
with a wrong gas (e.g. starting a span cali-
bration while zero gas is owing), resulting
in an instrument out of tune (see example to
the left side).
There are situations, when deviation toleran-
ce check must be disabled, e.g. during rst
time calibration after changing the span gas
concentration. In this cases select Off.
Tolerances
Deviat. toler.: Off
Zero limit: 20.0 %
Span limit: 20.0 %