DH Instruments PPCK PLUS, Operation And Maintenance Manual

Page: 131 / 150

PPCK+™ Operation and Maintenance Manual
Page 123
©2001 DH Instruments, Inc .
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OPERATION
The typical procedure for calibrating an RPT range is:
n
Set-up and prepare the PPCK+ for calibration (see Sections 5.2.2, 5.2.3).
o
From the main run screen, using the [RANGE] function key, select the range to be
calibrated (see Section 3.2.1). Set the HEAD to zero using the [HEAD] function
(see Section 3.2.7). Turn AutoZ ON if it is left ON in normal PPCK+ operation
(see Section 3.4.1).
p
Pressing [SPECIAL] , <4Internal> , <2Cal> , <1RPT> , <1view> , read and record the
current values of PA and PM.
q
Pressing [SPECIAL] , [1Autoz] , [2View] , read and record the current value of
ZOFFSET (for absolute mode only).
r
Allow the PPCK+ to warm-up with power on for at least 30 minutes before running
the calibration.
s
Apply the calibration pressure for each point (normally atmosphere – FS – zero in
20 % increments. Dwell at least two minutes after setting the reference pressure at
each point to allow full stabilization. Record the pressure the value of the pressure
applied by the reference and the value indicated by the PPCK+ at each point.
The data recorded is the "as received" data for this calibration.
t
Enter the calibration pressure and PPCK+ readings into a computerized
spreadsheet. Calculate the "non-corrected" PPCK+ readings by backing out the PA,
PM and ZOFFSET (absolute mode only) recorded in Steps
p
and
q
above,
following:
non-corrected reading = (corrected reading - PA + ZOFFSET)/PM
u
Perform a linear regression to find the offset and slope that best fit the non-corrected
PPCK+ readings to the calibration standard pressures. The offset is the new value of
PA, the slope is the new value of PM.
v
Press [SPECIAL] and select <4Internal> , <2Cal> , <1RPT> , <2edit> and write the
new calibration date and the new values of PA and PM for the RPT and
range calibrated.
w
Press [SPECIAL] and select <4Internal> , <2Cal> , <1RPT> , <3run ZNATERR> , to
run the ZNATERR routine (absolute mode calibration only) (see Section 5.2.6).
Calculate as left data for the calibration if desired following:
as left reading = (non-corrected reading • new PM) + new PA