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Emerson Process Management GmbH & Co. OHG 7-5
Instruction Manual
HASAxE-IM-HS
05/2006
7 Maintenance
7-3 Calibration Procedures
Calibration gases...
Tol.Check: Off
Purge time: 15 s
Interval time...
By default the option TOL. CHECK (tolerance
check) is disabled (OFF).
With tolerance check enabled ("10%") during
calibration the analyzer checks that the ente-
red (setpoint) values for zero gas and span gas
are reasonable compared to the currently
flowing calibration gas. If this gas concentration
differs more than 10 % of measuring range
from zero (during zero calibration) or span gas
setup (during span calibration), calibration is
aborted and a maintenance request alarm is
set (LED and relay output). Resetting the alarm
requires to perform a valid calibration or to
confirm it within the CONTROL ->
ACKNOWLEDGE-MENTS.. screen.
The 3rd option (AutoOff) has the same
functionality as 10% except that the main-
tenance request is reset after 2-3 minutes.
So tolerance check helps avoiding calibrating
with a wrong gas applied (e.g. starting a span
calibration while zero gas is flowing) resulting
in an instrument out of tune.
There are still situations when tolerance check
must be disabled, e.g. when calibrating after
changing the span gas concentration.
Example:
Measuring range: 0 ... 50 %
Zero gas: 0 %
Span gas: 50 %
Tolerance check disabled (Off):
Starting a span calibration with zero gas con-
nected instead of span gas, the analyzer
calibrates the span with the wrong gas resulting
in an analyzer out of tune.
Tolerance check enabled(10%; AutoOff):
Starting a span calibration with zero gas con-
nected instead of span gas, the analyzer
gives an error message and stops calibrating
because the measured (expected span gas)
value differs more than 10 % 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
request is stored and re-activated again, when
the tolerance check is enabled somewhere in
the future!