Calibration Of Reference Pressure Transducers (Rpts); Principle - Fluke MOLBOX RFM Operation And Maintenance Manual

molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL
5.2 CALIBRATION OF REFERENCE PRESSURE
TRANSDUCERS (RPTS)
5.2.1

PRINCIPLE

molbox RFM has two absolute Reference Pressure Transducers (RPTs):
•
One to measure molbloc upstream pressure
•
One to measure molbloc downstream pressure
If molbox RFM is equipped with the microrange option (see Section 3.1.5), it also has a third
low differential RPT.
To calibrate an RPT, pressures from a pressure standard are applied to the RPT at
ascending and descending pressure points over the RPT range. The pressure defined by
the standard and the corresponding RPT readings are recorded at each point. After all of the
pressures have been applied and recorded, adjustments are made to fit the RPT pressure
readings to the standard. Fitting the readings means performing a least squares linear
regression to arrive at the lowest value of the residual of errors of the transducer relative to
the standard. The transducer readings are adjusted by user settable coefficients: PA (a
pressure adder or offset) and PM (a pressure multiplier or span set) (see Section 5.2.1.1).
molbox RFM provides complete local and remote access and control of RPT
calibration parameters.
equipment needed and recommended procedures for calibration of the molbox RFM RPTs.
CalTool for RPTs software provided with the molbox RFM supports the calibration process
of molbox RFM RPTs.
Accessories CD (white) with each new system. Most users should use CalTool software
to assist in the calibration of the molbox RFM. The latest version of this software is
always available for download, free of charge, from www.dhinstruments.com.
CalTool for RPTs steps the operator through the complete reference transducer calibration
procedure.
calculating the optimum calibration coefficeints, evaluating the calibration results, writing the
new coefficients to the molbox RFM and generating the calibration reports. (See the CalTool
for RPTs manual also found on the General Accessories CD and www.dhinstruments.com.)
molbox RFM also provides complete front panel and remote access to RPT calibration
parameters so that the RPT calibrations can be performed without using CalTool software
(see the following sections).
molbox RFM1 is delivered with an interactive reference pressure transducer (RPT) calibration
utility software program that steps the operator through the complete RPT calibration
procedure including applying pressures, collecting data automatically, calculating new PA
and PM values, previewing the results of the new calibration and activating the results of the
new calibration (see the CalTool for RPTs program and documentation provided on the
General Accessories disk delivered with molbox RFM). molbox RFM also provides complete
local and remote access to RPT calibration coefficients so that RPT calibrations can be
performed without using CalTool software if desired (see Section 5.2.5).
CalTool for RPTs software provided with the molbox RFM supports the calibration process
of molbox RFM RPTs. The CalTool program and its manual are provided on the General
Accessories Disk with the new molbox RFM. Most users should use CalTool software to
assist in the calibration of molbox RFM RPTs.
© 1998-2007 DH Instruments, a Fluke Company
Section 5.2 of this manual provides complete information on
CalTool and its documentation are provided on a General
It is capable of applying the necessary test pressures, gathering the data,
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