PPCH™ OPERATION AND MAINTENANCE MANUAL
© 2009 DH Instruments, a Fluke Company
Page 58
As a general rule, the maximum acceptable leak rate for optimal PPCH automated pressure
control operation and to assure in tolerance measurements with default pressure control parameters is
0.005 % of reading/second. In dynamic control mode, to handle higher test system leak rates, try
using hi volume dynamic control (see Section 3.4.6.2) and/or increase the hold limit using [SPECIAL],
<6control>, <1limits> (see Section 3.4.6.1).
To view the results of the most recently completed leak check, press
<2view>
.
Press
[ENTER]
or
[ESC]
to return to the MAIN RUN screen. If NO leak check data is stored
(i.e., if the PPCH has never run a leak test or a reset has cleared previous leak test results),
the results screen displays
<Data NOT available>
briefly and returns to MAIN RUN screen.
Leak check is range specific in the sense that leak check is run using the active range.
However, only one set of leak check results is maintained in memory and each leak test completed
overwrites the memory. View leak check always shows the results of the last leak check run
regardless of the range that is now active. The results screen includes the range indicator to
indicate the range in which the leak check was run.
3.3.10
[ENT/SET P] (SET PRESSURE AUTOMATICALLY)
PURPOSE
To enter and execute target pressure and ramp values for PPCH automated pressure control.
See
Section
3.2.2 for information on automated pressure control and the different control
modes available with PPCH.
OPERATION
The operation of
[ENT/Set P]
depends on the active pressure control mode.
Dynamic mode:
See Section 3.3.10.1.
Static mode:
See Section 3.3.10.2.
Monotonic mode:
See Section 3.3.10.3.
Ramp mode:
See Section 3.3.10.4.
Interrupting automated pressure control:
See Section 3.3.10.5.
Automated commands for zero pressure:
See Section 3.3.10.6.
The active range pressure control mode and parameters can be viewed and edited using
[SPECIAL], <6control> (see Section 3.4.6).
3.3.10.1
DYNAMIC CONTROL MODE, [ENT/SET P]
If the PPCH is not set for dynamic control, use
SPECIAL, <6control>
,
<2mode>
to select dynamic control mode.
For best results, wait 5 minutes with the PPCH vented before controlling
pressure when changing to or from dynamic control mode. This is to allow time for
the PPCH thermal pressure control unit to respond and stabilize.
