58 Rev. 2
Calibration
Capacitance-Based Level Calibration : Closed Dewar Calibration Procedure
9. The instrument will display
the following screen as it takes
data for several seconds. Once
the calibration measurement
is completed, press the SAVE
button.
Note
Note that the frequency listed
to the right of the PERFORM
MAX CAL button is updated as well as the date and time stamp of
the calibration point.
10. To achieve a standard calibration of the sensor with the active
region located from the lower hole to one inch below the upper hole,
use the level data from the instrument to recalibrate the maximum
point when the percent level corresponds to one inch below the
upper hole. Use the following equation to determine the percent
level at which to reset the maximum calibration point:
where L
active
is the active length of the sensor in inches. This
technique can be used assuming the sensor was built as a standard
sensor. If the sensor was made in a custom configuration, refer to
the sensor documentation and/or drawing or contact AMI.
Example
: 20" active length sensor:
When the sensor is calibrated by the closed dewar procedure, the
actual length of calibration will be 21" (distance between the
bottom and top holes in the sensor). When the liquid is 1" below the
upper hole, the display will show 95.2% [e.g. 100% (1"/21" x 100%)
]. When the liquid level reaches this point during usage, perform
the PERFORM MAX CAL operation. The instrument and sensor are
now calibrated with a standard active region of 20". The length
setting of the sensor in the instrument should also be configured for
50.8 cm (20").
Proceed to the Operation section for directions for configuring the
instrument.
Figure 4-43. Updated MAX CAL
Frequency
MAX
percent
100 100
1
L
active
---------------
–=
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