Rev. 2 43
Calibration
Capacitance-Based Level Calibration : Selection Flowchart
Occasionally customers ask AMI to calibrate an instrument and Sensor
Transmitter for a liquid which is not available at AMI for calibration
purposes and/or for a sensor which is too long to be calibrated at our
facilities. For the case of the target liquid being unavailable, AMI uses
liquid nitrogen as the reference liquid and an Approximate Calibration is
performed using mathematical manipulation of the ratio of the dielectric
constants between liquid nitrogen and the desired liquid. The technique is
intended to provide the instrument with an approximate calibration so
that it can be used immediately by the customer. However, the customer is
Figure 4-7. Calibration method selection diagram.
Instrument &
sensor purchased
together?
START
Verify sensor
specifications
Verify calibration
sticker on bottom of
instrument
Perform Open
Dewar Calibration
Is factory
calibration
correct?
Can Open
Dewar Calibration be
performed in target
liquid?
Can Closed
Dewar Calibration be
performed in target
liquid?
Perform Closed
Dewar Calibration
Perform
Approximate
Calibration
Go to Operation
Y
N
N
Y
N
Is factory
calibration
Approximate?
Y
Y**
N
** Factory Approximate Calibration should only be used if
open dewar or closed dewar calibration is not feasible in
the target liquid at the customer's facility.
N
Can Open
Dewar Calibration be
performed in target
liquid?
Can Closed
Dewar Calibration be
performed in target
liquid?
Y
Y
N
NY
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