PPCH-G™ OPERATION AND MAINTENANCE MANUAL
© 2007 DH Instruments, a Fluke Company
Page 130
5.2.8
Q-RPT CALIBRATION/ADJUSTMENT WITHOUT CALTOOL
FOR RPTS SOFTWARE
PRINCIPLE
The PPCH-G Q-RPTs can be calibrated and adjusted without using CalTool for RPTs
software. This requires:
•
Applying pressures with a calibration standard and recording the pressures measured by
PPCH-G.
•
Calculating new PA and PM values and entering them.
•
Setting
P
offset
to zero for Q-RPTs that will be used in absolute mode.
Before proceeding to calibrate a reference pressure transducer without using CalTool for
RPTs software, Sections 5.2.1, 5.2.2 and 5.2.3 should be reviewed thoroughly.
PPCH-G must be in a pressure control mode OTHER THAN piston gauge mode when it is
calibrated. The control character in the middle of the bottom line of the display must be other
than <P> (see Section 3.4.6.2).
OPERATION
The typical procedure for calibrating a Q-RPT is:
Set-up and prepare the PPCH-G for calibration (see Sections 5.2.2, 5.2.3).
Use
the
[RPT]
function key to select the Q-RPT to be calibrated (see Section 3.3.5). Be
sure to set the DF range (not an AutoRanged range).
Use
[HEAD]
to set the HEAD to zero (see Section 3.3.7). Use
[UNIT]
to set the desired
pressure unit of measure (see Section 3.3.2). Use
[MODE]
to set the desired pressure
measurement mode (see Section 3.3.3). PPCH-G Q-RPTs that will be used in gauge
measurement mode only, may be calibrated in gauge measurement mode with a gauge
pressure standard (see Section 5.2.5).
Use
[SPECIAL]
,
<1AutoZ>
to access the AutoZ function (see Section
3.5.1).
If calibrating in absolute measurement mode, turn AutoZ ON if it is left ON in normal
PPCH-G operation.
If calibrating in gauge measurement mode, always turn AutoZ ON.
Use
[SPECIAL]
,
<8cal>
,
<1Hi RPT>
or
<2Lo RPT>
,
<1view>
, to read and record the
current values of PA and PM for the Q-RPT to be calibrated. If calibrating in absolute mode,
also record the value of P
offset, abs
.
Run the recommended calibration point sequence for the Q-RPT (see Section 5.2.4)
recording the pressure applied by the standard and the PPCH-G reading at each calibration
point. The data recorded is the “as received” data for this calibration.
Enter the calibration pressures and PPCH-G readings into a spreadsheet. Calculate the
“non-corrected” PPCH-G readings by backing out the PA, PM and P
offset, abs
(P
offset, abs
is
necessary only if the Q-RPT is being calibrated in absolute mode) recorded in Steps and
above, following:
non-corrected reading = ((corrected reading - PA)/PM ) + P
offset, abs
Perform a linear regression to find the offset and slope that best fit the non-corrected
PPCH-G readings to the calibration standard pressures. The offset is the new value of
PA, the slope is the new value of PM.
