Metek DREXELBROOK Universal IV Lite, Installation And Operating Instructions Manual

Page: 43 / 110

Configuration & Calibration
37
3.11 Validation
More and more industries are requiring formal validation
of their processes for their customers as well as for various
government regulatory agencies. The Universal IV Transmitter
has this capability built in.
3.11.1 Validation Design Concept
Smart RF Continuous Level systems derive their input
information from a sensing element that provides a capacitance
value to the RF Transmitter. The RF Transmitter output signal
is derived from this capacitance value, based on the capacitance
span of the transmitter during initial calibration.
If the RF Transmitter's minimum and maximum capacitance
values are known, and remain unchanged, the effect of a specific
capacitance value within this range can be accurately predicted.
If a known capacitance (which can be NIST-traceable) within
this range produces repeatable results and the minimum and
maximum values remain unchanged the RF Level system can be
assumed to be operating correctly.
With a known capacitance input, the output signal would not be
repeatable if the calibration information is altered, or if the RF
transmitter was not operating within specifications. Repeatable
calibration information can be maintained through the use of the
Save/Print capability built into the Universal IV Transmitter.
3.11.2 Validation Procedures
A. Drexelbrook Laptop software must be used. Connect
the laptop to the smart level transmitter signal loop
to be validated and start the software according to the
instructions provided at the beginning of this Section 3 .
B. At the Main configuration screen observe the Level
Calibration, Lower Capacitance, and Upper
Capacitance values and the Lower Level and Upper
Level values. Select an NPO Capacitor (which can
be NIST traceable, if desired or required) that falls
somewhere mid-range. Example: See Fig. 3-17. If
Lower Capacitance is 50pF and Upper Capacitance
is 2000pF, that corresponds to a Lower Level and
Upper Level of 0-10 feet. Select an NPO Capacitor
of approximately 1000pF. [Drexelbrook 401-0006-
008 Capacitor Substitute Box may also be used; it is
traceable to NIST].