5. MAINTENANCE, ADJUSTMENTS AND CALIBRATION
Page 127
© 2007 DH Instruments, a Fluke Company
Table 23.
Calibration point sequence, PPCH-G Q-RPTs
CALIBRATION
SEGMENT
POINT
NO.
POINT
[% OF SPAN]
1 Lowest
Pressure
1
2 25
%
3 50
%
4 75
%
Ascending
5 100
%
6 75
%
7 50
%
8 25
%
Descending
9 Lowest
Pressure
1
1
In absolute mode, a point at or near atmospheric pressure. Zero
(vented) in gauge mode.
PPCH-G Q-RPTs that will NOT be used in absolute measurement mode may be calibrated in
gauge measurement mode with a gauge pressure standard. PPCH-G Q-RPTs calibrated in gauge
measurement mode by applying gauge reference pressure values should be used in gauge mode
only (see Section 5.2.5).
5.2.5
TURNING OFF ABSOLUTE MEASUREMENT MODE FOR A
Q-RPT
PURPOSE
To prevent selection of absolute measurement mode for a Q-RPT.
PRINCIPLE
PPCH-G Q-RPTs are intrinsically absolute (Axxx type) but are frequently used in gauge
measurement mode only (see Section 3.3.3
PRINCIPLE). PPCH-G Q-RPTs that are used
in gauge mode only, may be calibrated in gauge mode with a reference that applies gauge
pressures. Calibration with an absolute reference is not necessary. However, if a PPCH-G
Q-RPT is calibrated in gauge mode, it is not possible to know if it is in or out of tolerance in
absolute mode. To avoid using absolute measurement mode on a Q-RPT that is calibrated
for gauge mode only, access to absolute mode can be turned ON and OFF. This is
accomplished in the
[SPECIAL], <8cal>
menu.
OPERATION
See
Section
5.2.7 for more detailed information on editing and viewing Q-RPT calibration
information. See Section 3.5.5.5 for information on the PPCH-G security system to prevent
access to Q-RPT calibration editing.
Turning absolute mode operation ON and OFF for a Q-RPT occurs in the same area in which
calibration coefficients are edited. To access the Q-RPT calibration editing area press
[SPECIAL]
,
<8cal>
and select the desired Q-RPT. Then select
<1edit>
to make changes
(see Section 5.2.7).
[ENT]
through the calibration information. After
viewing the values of PA and PM the display is:
Absolute mode: HI
1off 2on
The cursor is on the number corresponding to the current selection. Make the desired
selection.
<1off>
causes absolute mode to be unavailable for the Q-RPT in normal
measurement and control operation.
