DH Instruments PPC4, Operation And Maintenance Manual

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3. OPERATING PRINCIPLES
Page 27 © 2009 DH Instruments, a Fluke Company
AutoRanged ranges or generate pressures above the SDS pressure
rating the RPM4 must be disconnected or the RPM4 SDS must be
upgraded to a higher pressure rating. Upgrades may be done at the DH
Instruments service center (see Table 36).

OPERATION
For Basic Interface see Section 4.5.10.
For Advanced Interface see Section 5.7.1.
3.2.9 Range

PURPOSE
To view and/or change the active pressure measurement range and associated settings.
Note
Range selects from existing ranges in the Basic Interface and saves current
AutoRanged Ranges. See AutoRange to create ranges (see Section 3.2.8) or
to select Ranges in the Advanced Interface (see Section 5.7.1).

PRINCIPLE
A PPC4 range is defined as a pressure span and associated settings (see Section 3.2.8).
A PPC4 may have multiple ranges. Each Q-RPT (and the utility sensor if present) available to
the PPC4 system has a default range which is its maximum full scale. Additional ranges,
lower than the Q-RPT’s full scale, may also be created using AutoRange (see Section 3.2.8).
Ranges created using AutoRange may be saved with all their settings for reactivation (see
Section 5.7.1 for the Advanced Interface and Section 4.4.1.1 for the Basic Interface).
Range allows the available PPC4 pressure ranges to be viewed and selected, including
automated switching of both internal and external Q-RPTs when necessary.
Note
•
Range full scale limits are given in the pressure unit that is currently
active for that range. Change the active unit to display the range limits
in a different unit.
•
Many PPC4 settings and functions are range specific. See Table 4 for
identification of range specific settings.
•
To protect against overpressure situations and for maximum
measurement performance, the active range can only be changed when
the system is vented. When prompted by the PPC4,

causes PPC4 to
vent and then complete the range change.
•
Before operating PPC4 with external Q-RPTs, check carefully that the
external Q-RPT TEST(+) port is connected to the PPC4 TEST(+) port. If
the external Q-RPT is NOT connected to the PPC4 TEST(+) port, it will
not measure the pressure generated by PPC4 and PPC4 may reach a
pressure higher than the target pressure before its watchdog function
recognizes that the external Q-RPT is not connected.
3.2.10 Unit

PURPOSE
To select the unit of pressure in which PPC4 displays pressure values.