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molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL
SYMPTOM
Displays <******> where a numerical value
should go.
Bottom line of display has changed and
you want to change it back.
Bottom line of display is blank.
Display is showing pressure values and
flashing, beeper is sounding two second
beeps.
Display is showing <OVERP!>.
Display is showing <BPR HI> where the
flow value should go.
Flow indicated by molbox RFM never
becomes stable.
A Ready (<*>) indication is never achieved
during molbloc-L operation.
Ready (<*>) indication does not seem to
be based on current stability setting.
Flow indication is flashing during
molbloc-L operation
Flow indication is flashing during
molbloc-S operation
Pressure indicated by molbox RFM never
becomes stable.
Flow indication appears to be grossly
incorrect.
Flow indication appears to be grossly
incorrect.
During molbloc-S operation, there is no
flow through the molbloc but molbox RFM
is indicating a large flow value.
Flow indication appears to be incorrect.
© 1998-2007 DH Instruments, a Fluke Company
Table 25. Troubleshooting Checklist (Continued)
PROBABLE CAUSE
Number to be displayed is too
large for allocated space. Usually
due to an erroneous setting or
measurement causing an out of
limit value to be calculated.
The DISPLAY function has been
used to change the display.
DISPLAY mode is "clean".
Pressure applied to one or both of
the
absolute
RPTs
overpressure.
One
or
both
of
absolute
RPTs
overpressured.
molbox RFM is connected to a
molbloc-S
and
the
downstream pressure to upstream
pressure (B\PR) is too high to
make a valid flow measurement.
The flow through the molbloc is not
stable.
Flow stability criterion is never
being met.
The flow is within the stability limit
but the Reynolds number of the
flow
exceeds
the
acceptable limit of 1 200.
Reynolds number is greater than
1300
Back pressure ratio is too high to
establish critical flow through the
molbloc-S.
There is a leak in the molbox RFM
and/or in the system to which it
and the molbloc are connected.
Your assumption of flow in the
system is grossly incorrect.
The molbloc connected to molbox
RFM has been swapped without
reinitialization so molbox RFM is
still using characteristics from a
previous molbloc.
molbox RFM is in BPR OFF mode
and flow is being calculated from
upstream
absolute
without knowledge of downstream
pressure.
molbox/molbloc and/or the device
you are comparing it to are in
tolerance
but
you
properly evaluated the tolerance
limits.
Page 150
Check settings that may be causing an out
of
limit
measurement
necessary. (3.4.5, 3.4.1, 3.5.6)
Use [DISPLAY] to set bottom line to desired
display. (3.4.6)
Operation is normal.
change
bottom
(3.4.6.6 and 3.4.6)
Reduce pressure applied to upstream (HI)
is
near
and downstream (LO) molbloc pressure
connection ports. (3.6.3)
the
molbox
Remove the source of overpressure and
has
been
press [ENTER] to clear.
RPTs for damage. (3.6.3)
Operation is normal.
ratio
of
increase
upstream
decrease downstream pressure. 3.1.2, 3.6.9
molbox RFM passively measures the flow
through the molbloc.
flow.
Correct conditions that are causing
unstable flow.
Adjust stability criterion or stabilize flow.
(3.5.5, 3.1.3)
Operation is normal. (3.5.5, 3.1.3)
maximum
Operation is normal. Indicates that flow is
beyond the molbloc-L range (1.2.4.1.3,
1.2.4.1.4, 3.2.1, 3.1.3)
Operation is normal.
upstream pressure or reduce downstream
pressure to reduce BPR below the BPR
limit at the current Reynolds numbers.
3.1.2, 1.2.4.2.1.
Find and correct leak.
molbox RFM LEAK CHECK functions.
(3.4.4.3)
Check and adjust flow in the system.
Reinitialize
molbloc
(3.4.8)
Behavior is normal.
evaluating flow measurements when using
pressure
molbloc-S.
Also consider changing BPR
mode to Auto or ON. 3.1.2, 3.6.9, 3.4.4.5
Determine flow measurement tolerance of
molbloc/molbox
have
not
comparing with.
relative to the combined tolerance of the
two. (1.2.4)
SOLUTION
and
adjust
if
Use [DISPLAY] to
line
display
if desired.
Check molbox
Increase flow to
pressure
and/or
It does not control
Increase molbloc-S
Consider using
using
[molbloc].
Consider BPR when
and
device
you
are
Evaluate "correctness"
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