AMI 1700 - Completing the Closed Dewar Calibration Procedure; Figure 4-39 PERFORM MAX CAL. Selection Button; Figure 4-40 PERFORM MAX CAL. Selection Button

Rev. 2 55
Calibration
Capacitance-Based Level Calibration : Closed Dewar Calibration Procedure
7. Connect the sensor to the oscillator coaxial cable that is connected
to the instrument.
8. Perform the maximum level
calibration by invoking the
maximum calibration function
by pressing MENU >
SENSORS > CALIBRATE
NITROGEN > PERFORM MAX
CAL.
9. Save the calibration value.
10. Calculate the factor C
adj
using
the following equation:
where L
total
is the total sensor length in inches, L
active
is the active
sensor length in inches, and e is the dielectric constant of the target
liquid.
11. Enter C
adj
into the instrument
by touching the APPROX CAL
VALUE: field.
12. Using the pop up numeric
keypad, enter the C
adj
value
and press the APPLY button.
13. With the sensor connected,
again press the PERFORM
MIN CAL button. The
presetting procedure is complete. Proceed to the remainder of the
closed dewar calibration procedure as presented below.
4.2.8.2 Completing the closed dewar calibration procedure
1. Install the sensor in the dewar and energize the instrument with
the sensor connected to the instrument via the oscillator (if
required) and extension cable(s) (see the system diagram on
page 2).
2. Connect a strip chart recorder or graphical data logging application
to the recorder output terminals on the rear panel of the
instrument. If the recorder output is not available, the 4-20 mA
current loop output may be used if installed, or an installed
Figure 4-39. PERFORM MAX CAL.
Selection Button
C
adj
120 1
2.1 L
active

5.2 L
total

----------------------------
+
e 1–
0.454
-------------
=
Figure 4-40. PERFORM MAX CAL.
Selection Button