Specifications

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