American Magnetics 185 & 186 Liquid Level Instruments (CE-Marked) - Manual (Page 37)

Rev. 3 27
Calibration
Approximate calibration
Note
The last approximate calibration factor is not retained in the
instrument memory, therefore the effects of repeated approximate
calibrations are cumulative.
Example: Purchased a 100" active length sensor for operation in
liquid argon at atmospheric pressure, however only liquid nitrogen
is available for calibration at a maximum depth of 30":
First, the sensor is dipped as far as possible into the liquid nitrogen
and cooled. The MIN point is then set as outlined in step 2. The
MAX point is set as outlined in step 3 while the sensor is
submerged 30" in liquid nitrogen. The dielectric constant for liquid
nitrogen is 1.454 and for liquid argon is 1.53. Substituting all
values into the approximate calibration factor equation yields:
A value of 389.1 would be entered as the approximate calibration
factor as outlined in steps 6 and 7. The sensor is now approximately
calibrated for 100" active length operation in liquid argon.
8. The sensor can now be installed in the dewar containing the target
liquid. The approximate calibration can be used until an open
dewar or closed dewar calibration can be performed with the target
liquid.
9. Proceed to the Operation section for directions for configuring the
instrument.
Approximate Calibration Factor
1.53 1 –
1.454 1 –
---------------------- 100
Ч
100
30
--------- 389.1 = =