PPC3™ OPERATION AND MAINTENANCE MANUAL
© 2002-2007 DH Instruments, a Fluke Company Page 12
2.3.8.2 INSTALLING A DUAL VOLUME UNIT (DVU), G15K AND
BG15K Q-RPTS
To achieve in tolerance pressure control with the very low range of the G15K and
BG15KQ-RPTs, a PK-PPC-BG-DVU dual volume units should be installed in-line
on the TEST(+) and TEST(-) ports. The DVU includes two thermally isolated
volumes installed in the test line to improve control stability.
See the PK-PPC-BG-DVU instruction sheet for additional information on its
installation.
2.3.9 THE VENT PORT
The PPC3 VENT port is the system vent to atmosphere point used to set zero gauge pressure as
well as to obtain Q-RPT measurements of atmospheric pressure. The PPC3 on-board
barometer, if present is connected to the VENT port. Though a pressure hose can be
connected to the VENT port to direct the vented gas flow, a completely unobstructed
connection to atmosphere must be maintained for PPC3 reference pressure measurements
to operate normally.
The PPC3 VENT port fitting is 10-32 UNF.
NEVER plug, obstruct or connect a supply pressure to the PPC3 VENT port. This may
adversely affect GAUGE mode operation and AutoZeroing functions.
2.3.10 CHECK/SET SECURITY LEVEL
PPC3 has a security system based on user levels. By default, the security system is set to
“low”, which includes certain access restrictions, and there is no password required to
change the security level. See Section 3.5.5.5 for information on the security level system.
As part of the PPC3 startup, determine the security level that is appropriate for the PPC3 and
set a password if desired.
PPC3 is delivered with the security level set to “low” to avoid inadvertent altering of critical
internal settings but with access to changing security levels unrestricted. It is recommended
that the low security level be maintained at all times and password protection be
implemented if control over setting of security levels is desired.
2.3.11 TURN OFF ABSOLUTE AND NEGATIVE GAUGE MODE
(AXXX RPT)
If your PPC3 has an Axxx (absolute) Q-RPT, it is able to operate in gauge,
negative gauge and absolute measurement modes (see Section 3.3.3).
If the PPC3 will be used only in gauge mode, the other measurement modes can
be turned off so they are no longer accessible. This can avoid confusion and/or
accidental use of the wrong measurement mode. See Section 5.2.5 for complete
information on turning off absolute and negative gauge measurement modes.
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