PPCH™ OPERATION AND MAINTENANCE MANUAL
© 2009 DH Instruments, a Fluke Company
Page 176
SYMPTOM
PROBABLE CAUSE
SOLUTION
Apparent inaccurate pressure
control/measure when using
Internal, Hi (IH) RPT.
The IH transducer is a utility sensor, not a Q-
RPT.
Operation is normal for lower specifications
of utility sensor. 1.2.2.2
Incorrect pressure units and/or measurement
mode (gauge or absolute).
Set desired pressure units and/or
measurement mode. 3.3.2, 3.3.3
Q-RPT calibration coefficients have been
altered.
Check and correct calibration coefficients if
needed. 5.2, 5.3.7
Apparent inaccurate pressure
measurement/control.
AutoZ has been run and turned ON with an
incorrect standard for zero.
Check value of P
offset
. Rerun AutoZ with a
valid reference. 3.5.1
Apparent inaccurate pressure
measurement/control and
<h>
is
displayed on top line of screen.
An unplanned “head” correction is active or
head height or fluid is incorrect.
Operation is normal. Remove or change
“head” correction. 3.3.7
Q-RPT is recovering from rapid
depressurization.
Wait for Q-RPT recovery.
Pressure indication is negative.
Control mode was changed from dynamic to
another mode while not vented.
It is preferable to be vented when changing
measurement modes and to wait 5 minutes
while vented when changing to or from
dynamic control mode.
Measurement mode is absolute and
indication is absolute pressure at
atmosphere which is not zero.
Check measurement mode setting. 3.3.3
Measurement mode is gauge and AutoZ is
OFF so PPCH is not rezeroing.
Turn AutoZ ON. 3.5.1
PPCH is vented but does not
indicate zero.
Measurement mode is gauge and a head
correction is applied. When the gauge
pressure at the PPCH is zero, the gauge
pressure at the level of the head is not zero.
Change the head correction if desired.
3.3.7
VENT
port is plugged.
Open
VENT
port to atmosphere.
Vent valve not operating.
Contact
DHI
Authorized Service Provider.
Table 31
Will not vent.
Drive air supply is too low to open vent valve.
Check drive air supply. Observe pump
drive pressure. 2.3.5, 3.5.7.3
PPCH beeps rapidly ten times
and/or bottom line of main run
screen displays
<Reservoir level
low>
.
The PPCH fluid reservoir is low and in
danger of being empty.
Fill reservoir immediately. 5.6
