Metek DREXELBROOK Universal IV Lite, Installation And Operating Instructions Manual

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Universal IV - Installation and Operating Instructions
54
4.3 Calibration
There are two methods of calibrating the Universal IV
transmitter: Point Calibration or Capacitance Calibration .
Point calibration uses the actual level in your vessel for
calibration. The further apart the two points are for the
calibration, then the better the accuracy of the overall
measurement.
Capacitance calibration uses values obtained from the
Drexelbrook Service department (or a previous calibration or
identical application) for the zero and span calibration data.
Call 1-800-527-6297 for assistance. Please complete the Bench
Calibration Information Sheet on Page 50 and Fax to 215-443-
5117.
It is permissible or sometimes even recommended that both
methods be used in order to establish a calibration standard.
For example, if the vessel was already filled before the
calibration was attempted and it is difficult or impossible to
lower the level to establish the second point, it would be best to
use a calculated zero capacitance for the low point and actual
level for the high point. While this wouldn’t be as accurate as
two known level points, it will be reasonably accurate until an
actual low point can be established. The Service department will
help in calculating high or low capacitance values.
4.3.1 Point Calibration
Following is the sequence for Point Calibration using a handheld
Calibrator.
Equipment Required:
• Universal IV HART® Smart Transmitter
• HART® Communicator
• 24V Power source
• 250 ohm minimum loop resistance
• Two known process levels applied to the sensing element
This procedure uses an example of a point calibration for full-
scale (20mA) = 35 ft. and zero (4mA) = 1.5 ft.