PPCH™ OPERATION AND MAINTENANCE MANUAL
© 2009 DH Instruments, a Fluke Company
Page 62
See Section 3.4.6 for information on customizing pressure control
parameters.
3.3.10.4
RAMP CONTROL MODE, [ENT/SET P]
If the PPCH is not set for ramp control, use
SPECIAL, <6control>
,
<2mode>
to
select ramp control mode.
Use ramp control with caution. An ascending ramp will not stop increasing
pressure until stopped by a new pressure command, aborting control or reaching the
active range upper limit pressure (see Section 3.4.4).
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.
Press
[ENT/SET P]
from the MAIN RUN screen. The display is:
1.
Standard MAIN RUN screen first line showing
measured pressure and active Q-RPT.
2. Edit field for the target ramp rate in current
pressure unit of measure per second.
20.007 MPa g HI
Target rate:1.0000/s
Edit the target ramp value as desired. Enter a negative value for a descending rate.
A rate entry of 0 is not accepted.
Press
[ENT/SET P]
to start pressure control to the target ramp rate and return to
the MAIN RUN screen. The MAIN RUN screen when pressure control is active is:
1.
Standard MAIN RUN screen first line showing
measured pressure and active Q-RPT.
Always shows measured pressure.
2. Actual pressure rate of change (
<R>
) at all
times.
3.
Current control mode indicator. Flashes when
automated pressure control is active.
Character is
<R>
for ramp control.
<C>
is
appended if custom control parameters are in
use.
25.377 MPa a HI
R 1.015/s R
Observe the
Ready/Not Ready
indicator LED (see Section 3.2.3) for indication of
when the target rate has been established within the rate hold limit. PPCH
continues controlling following ramp pressure control protocol (see Section
3.2.2.5) until automated pressure control is interrupted.
If PPCH is unable to control pressure or appears to control pressure poorly,
see Section 6 to troubleshoot.
