PPCH-G™ OPERATION AND MAINTENANCE MANUAL
© 2007 DH Instruments, a Fluke Company
Page 20
Some screens go beyond the two lines provided by the display. This is indicated by a
flashing down arrow in the second line of the display. Press the cursor control keys to move the
cursor to access the lines that are not visible or directly enter the number of the hidden menu
choice if you know it.
3.1.3
DIRECT PRESSURE CONTROL KEYS
Figure 5.
Direct pressure control keys
The direct pressure control keys provide direct manual control of pressure increase,
decrease, jog and vent. They can be useful in adjusting pressure when automated pressure
control to a target pressure or rate is not needed. The jog keys are also used to adjust the
target pressure during active dynamic pressure control.
Pressing the
[VENT]
key aborts automated pressure control if active and causes PPCH-G to
control pressure to near atmospheric pressure and then open the system vent valve (see
Figure 6). On-going execution of the vent function is indicated by lighting a RED LED just
above the
[VENT]
key. Completion of the vent process is indicated by the
Ready/Not Ready
indicator light becoming GREEN with the vent RED vent LED still lighted. The vent valve
remains open until the
[VENT]
key is pressed again, another direct pressure control key is
pressed, or an automated pressure control command is given. Removing electrical power
also closes the vent valve.
Pressing the
[
]
and
[
]
direct pressure control keys aborts automated pressure control if
active and causes pressure to increase or decrease at the slow slew rate. Holding the
[FAST]
key pressed while pressing the
[
]
or
[
]
key causes the pressure increase or
decrease speed to change from slow to fast.
Pressing the
[
]
and
[
]
direct pressure control keys has a different effect depending on
the PPCH-G’s current activity:
•
Pressure control idle:
Causes the pressure to jog or step by a fixed amount which is
set automatically depending on the range (see Section 3.4.6, Table 7). The amount can
be adjusted using
[SETUP]
,
<3jog>
or by pressing both the up and down jog keys
simultaneously (see Section 3.4.3).
•
Dynamic pressure control active:
Causes the target pressure to be changed by a fixed
amount which is set automatically depending on the range. One press causes one step.
The step value can be adjusted using
[SETUP]
,
<3jog>
or by pressing both the up and
down jog keys simultaneously (see Section 3.4.3).
•
Static pressure control active:
No effect while pressure is actively controlled, changes
pressure by jog amount when pressure is in hold limit waiting for stability.
•
Monotonic pressure control active:
No effect.
•
Ramp control active:
No effect.
Pressing the up and down pressure jog keys (
[
]
and
[
])
simultaneously is a shortcut
to the jog step size adjustment menu.
