PPCH-G™ OPERATION AND MAINTENANCE MANUAL
© 2007 DH Instruments, a Fluke Company
Page 84
3.5.7
<7INTERNAL>
PURPOSE
To view, set, adjust, and maintain various aspects of PPCH-G’s internal operation.
OPERATION
To access the internal selections press
[SPECIAL]
,
<7internal>
. The display is:
1config 2baro
The INTERNAL menu choices include:
<1config>
Run automated routines that readjusts PPCH-G internal pressure control
coefficients (see Section
3.5.7.1).
<2baro>
View the real time output of the on-board barometer (see
Section
3.5.7.2).
<3supply>
View the pressure measured by the high pressure supply transducer. (see
Section
3.5.7.3).
3.5.7.1
<1CONFIG>
PURPOSE
To run automated routines that determine control valve opening coefficients and
thermal pressure control (TPC) control coefficients.
PRINCIPLE AND OPERATION
These functions are considered part of PPCH-G maintenance and are therefore
covered in the maintenance section of this manual (see Sections 5.5, 5.6).
3.5.7.2
<2BARO>
PURPOSE
To view the value of atmospheric pressure as measured by the PPCH-G on-
board barometer.
PRINCIPLE
PPCH-G is equipped with an on-board barometer. The atmospheric pressure
measurements made by the on-board barometer are used for dynamic
compensation of atmospheric pressure when using an Axxx Q-RPT to make gauge
pressure measurements (see Sections 3.3.3,
PRINCIPLE, and 3.2.4). The
barometer, if calibrated, may also be used as a reference for AutoZ of Q-RPTs in
absolute measurement mode (see Section 3.5.1).
The on-board barometer is a low accuracy sensor used only for measuring
small changes in atmospheric pressure over short periods of time
(see Section 3.2.4) PPCH-G measurement uncertainty does not depend on the
measurement uncertainty of the on-board barometer unless the barometer is used
as a reference for AutoZ of Q-RPTs in absolute measurement mode.
OPERATION
To view the current reading of the on-board barometer press
[SPECIAL]
,
<7internal>
,
<2baro>
. The display is in the active pressure unit of measure
(see Section 3.3.2).
