3. OPERATION
Page 43 © 2002-2007 DH Instruments, a Fluke Company
The reference height of the PPC3
pressure measurement is the middle of
the PPC3 TEST port. The head height
should be entered as a positive value if
the device or system under test is
higher than the PPC3 and negative if it is
lower.
The HEAD function is NOT range specific. The HEAD ON or OFF status remains the same
as ranges are changed. Edits made to the head settings are independent of active range
or Q-RPT.
When a head correction is being applied, it is indicated by <h> in the top line of the MAIN
RUN screen (see Section 3.1.1). When the head correction is zero, the <h> is not shown.
To change units of head height between inches and centimeters and to change the test
gas species, use [SPECIAL], <3head> (see Section 3.5.3).
When using external Q-RPTs in RPM4, it is recommended that the RPM4 head height be
adjusted to the reference level of the PPC3 before connecting the RPM4. Then, the
normal PPC3 reference level to DUT head corrections can be made for all the Q-RPTs,
whether internal or external to PPC3.
3.3.8 [PURGE]
PURPOSE
To execute the PPC3 test system PURGE function using the optional Self Purging Liquid Trap
(SPLT). PURGE is used to collect and exhaust liquid contaminants from the device or
system under test before they reach the PPC3.
PRINCIPLE
PPC3 is designed to precisely set, control and measure gas pressure. Liquid contamination
of the PPC3 internal pressure control module and/or the Q-RPT module can cause poor
pressure control and interfere with pressure measurement. Liquid contaminants that may be
present in test devices or systems that are connected to the PPC3 TEST(+) port are likely to
make their way back to PPC3’s internal pneumatic system as the test device or system is
pressurized and depressurized by PPC3. To every extent possible, only clean hoses and
tubing should be used to connect PPC3 to test devices or systems and those devices and
systems should be free of liquid contaminants. However, in the event that PPC3 must used
to test devices or systems that may contain small amounts of liquid contaminants, a Self
Purging Liquid Trap (SPLT) accessory supported by the PURGE function is available.
Execution of the PURGE function is automated and proceeds as follows:
If current pressure is greater than 700 kPa (100 psi) gauge, pressure is controlled down
to less than 700 kPa (100 psi) gauge.
Pressure control stops and a 5 second wait occurs.
SPLT exhaust valve is opened.
PPC3 waits until pressure is less than 20 kPa (3 psi) gauge or 110 kPa (16 psi) absolute.
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