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Emerson Process Management GmbH & Co. OHG 6-13
Instruction Manual
HASAxE-IM-HS
05/2006
6 Initial Startup
6-2 Checking the Instrument's Setup
The "SpanRange" parameter is shown in the
MEASURING RANGE INFO Screen (
5-4-5-1, page 5-56) and always gives a value
in relation to the upper measuring range limit
of the selected channel.
The "SpanRange" parameter is factory set and
not operator changeable. It is used for diffe-
rent functionalities:
At first the "SpanRange" parameter defines the
maximum value a span gas may have:
For a given "SpanRange" value of 110 % this
means, the maximum span gas concentration
to be used for the selected channel is 110 % of
the maximum measuring range.
Example:
Oxygen measuring range is 10 %. If the
"SpanRange" value is 220 %, then the
permissible maximum span gas concentra-
tion is 22 %, which allows to use ambient air
(21 % O
2
) for calibration.
Example 1:
Maximum measuring range is 1000 ppm,
SpanRange is set to 100 %.
This means the SpanRange covers exactly the
measuring range and thresholds may not
exceed this range: Thresholds to be set
between 0 ppm and 1000 ppm.
Example 2:
Maximum measuring range is 1000 ppm,
SpanRange is set to 110 %.
This means the SpanRange exceeds the upper
measuring range by 10 %. In consequence this
means for the lower threshold limit, it may
exceed the lower range limit by 10 %, too:
For the values given above the threshold limits
may be set between -100 ppm and + 1100 ppm.
Example 3:
Maximum measuring range is 1000 ppm,
SpanRange is set to 220 %.
This means the SpanRange exceeds the
measuring range by 120 % in both directions
(220 % - 100 % = 120 %):
The threshold limits may be set between
-1200 ppm (-120 % of 1000 ppm) and
+2200 ppm (+120 % of 1000 ppm).
The second functionality of the "SpanRange"
parameter is to specify the range for setting
concentration thresholds:
After substracting 100 % from SpanRange, the
result gives the value to expand the measuring
range in both ("+" and "-") directions for setting
thresholds.
Table 6-2: Thresholds influenced
by SpanRange parameter
SpanRange
val ue
relative to
measuring
range
relative value
absolute
val ue
lower limit upper limit
Example 1
100% 0% 0 ppm 0 ppm 1000 ppm
Example 2 110% 10% 100 ppm -100 ppm +1100 ppm
Example 3
220% 120% 1200 ppm -1200 ppm +2200 ppm
Expanded range for
thresholds
SpanRange value exceeding
measuring range
Measuring range: 0 … 1000 ppm