PPC4™ OPERATION AND MAINTENANCE MANUAL
© 2009 DH Instruments, a Fluke Company
Page 94
following static or dynamic control operation protocol (see Section 3.2.2) until automated
pressure control is interrupted.
5.5.1.1 Interrupting Automated Pressure Control
Automated pressure control is interrupted by:
•
: Suspends control and remains in Main Run Screen. Does not vent
pressure. PPC4 passively measures the pressure applied to its
TEST(+)
port.
•
Selecting any field or shortcut key with the knob or the cursor control
keys
,
and
:
Suspends control and goes to the selected function.
Does not vent pressure. PPC4 passively measures the pressure.
•
Selecting and entering the target pressure screen with the knob or
pressing
: Suspends control and goes to Set Pressure screen. Does not
vent pressure. PPC4 passively measures the pressure applied to its
TEST(+)
port.
To resume automated pressure control, press select and enter the target
pressure screen or press
then ENTER a target pressure value.
5.5.1.2 Automated Pressure Commands for Zero
Pressure
Zero in
gauge
mode:
A command for automated pressure control to a target value of zero when in
gauge or negative gauge
measurement mode is interpreted in the same
manner as if
had been pressed
(see Section 3.2.14). A
Ready
condition occurs when the vent sequence has
completed, including running AutoZ if applicable (see Section 3.2.22).
Zero in
absolute
mode:
In response to a command for automatic pressure control to a target value of
zero when in
absolute
measurement mode, PPC4 opens its down control valves
fully to the
EXHAUST
port allowing the vacuum source connected to the
EXHAUST
port to pull down the pressure as far as possible (see Figure 31).
The down valves stay open until another pressure command is given or control is
aborted. How low the pressure in the PPC4 and the system connected to the PPC4
TEST(+)
will go is a function of the quality of the vacuum pump used, the
characteristics of the volume and tubing connected to the
TEST(+)
port and
PPC4’s internal restrictions.
A
Ready
condition occurs when the pressure control stability limit is reached (see
Section 3.2.3). Measured pressure will continue to display even when
Ready
.
5.5.2
Manual Pressure Control
PURPOSE
The manual pressure control keys provide direct manual control to increase, decrease, and
jog the PPC4 pressure.
OPERATION
or
when automatic control is not active causes pressure to increase or decrease at
the fast slew rate.
or
when automatic control is active produces no response.
or
when automatic control is not active causes pressure to increase or decrease at
the slow slew rate.
or
during dynamic control causes the pressure to jog or step by a fixed amount.
During active dynamic pressure control, they cause the target pressure to be changed by the
fixed amount. One press causes one step. The approximate value of the step is set
Summary of Contents for PPC4
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