2. INSTALLATION
Page 19
© 2009 DH Instruments, a Fluke Company
2.4.3.2
CHECKING GAUGE MODE PRESSURE MEASUREMENT
If the PPCH is not vented (VENT LED ON), press the
[VENT]
direct pressure
control key to vent it (see Section 3.1.3).
Use the
[RANGE]
function key to change ranges if necessary and select the
Q-RPT’s DF range (see Section 3.3.1). Press the
[MODE]
function key and
select
<gauge>
mode (see Section 3.3.3). Use
[UNIT]
to change the pressure
unit if desired (see Section 3.3.2).
It is normal for PPCH to indicate a value other than zero for up to thirty seconds
when first entering
gauge
mode. After ten to thirty seconds, the VENT LED
should flash and zero should be indicated. If this does not occur, check that the
AUTOZERO function is ON (see Section 3.5.1). If AUTOZERO is ON and the
displayed pressure will not zero when vented in gauge or bi-directional gauge
measurement mode, PPCH may need repair.
If a non-zero head correction value is active, PPCH will not indicate zero when
vented in gauge mode. Use [HEAD] to set the head height to zero (see Section 3.3.7).
Using the
[RANGE]
function key to change ranges, observe that zero is
indicated for each Q-RPT within 10 to 30 seconds.
2.4.4
PRIME AND PURGE TEST SYSTEM
For PPCH pressure control to operate properly, it is important to minimize the amount of gas
present in the system connected to the
TEST
port. The prime and purge functions are
intended to assist in removing gas from the test system before starting a test.
Prior to controlling pressure with PPCH, it is recommended that a priming and/or purging
procedure be completed (see Section 3.3.8).
2.4.5
LEAK CHECK
PPCH cannot control pressure properly if the system connected to the
TEST
port has excessive
leaks. See Section 3.3.9 or information on the PPCH leak test function.
For PPCH to operate properly, the leak rate in the test system after stabilization should not
exceed 0.005% of reading/second.
Verify the maximum pressure rating of the system connected to the PPCH TEST port before
entering a purge pressure value. Do not enter a purge pressure greater than the pressure rating
of the system or instruments connected to the PPCH TEST port.
2.4.6
CHECK PRESSURE CONTROL OPERATION
Select a pressure range using
[RANGE]
(see Section 3.3.1).
Press
[SETUP]
,
<6control>
,
<2mode>
,
<1dynamic>, <1standard>)
(see Section 3.4.6). If
PCH was not already set to dynamic control mode, wait 5 minutes for the thermal pressure
controller to stabilize.
Press
[ENT]
. Key in a target pressure within the active range and press
[ENT]
again
(see Section 3.3.10).
