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molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL
The next display is:
This display allows the current untared absolute pressures and the resulting untared
differential pressure from the difference of the two absolute RPTs to be observed.
The flow value represents the current untared zero error in terms of flow. It does
not necessarily represent the current zero error on flow measurements as a tare
value other than zero is probably already active.
Press [ENTER] when ready. Molbox RFM makes measurements to determine a
new tare value. The next display is:
Press [ENTER] to activate the new tare and return to the MAIN run screen.
Press [ESCAPE] to return to the [TARE] display without activating the new tare,
leaving the old tare active.
Limits and Errors
Excessively large tare values can diagnose molbox RFM transducer malfunction,
the need to recalibrate or possible poor execution of the TARE function. To
protect against improper taring and to alert to possible RPT malfunction, molbox
RFM checks the tare values before they are activated and displays warnings
when appropriate. In the most extreme case, molbox RFM will not allow the tare
value to be activated. The limits checked and their consequences are as follows:
Upstream and downstream absolute pressure RPTs coherence test:
When attempting to activate a new tare, molbox RFM checks the coherence
between
disagreements. The test has two levels.
If the new tare is 700 Pa < tare > 10 000 Pa, a caution message is displayed.
Pressing [ENTER] overrides the caution and activates the new tare.
Pressing [ESCAPE] returns to the TARE screen.
© 1998-2007 DH Instruments, a Fluke Company
1.
The current pressure read by the upstream
(left) and downstream (right) RPTs without
taking into account the current tare value.
These are untared readings in the current
pressure units.
2.
<T>, flashing, to indicate that this is a TARE
display showing the tare between the two
absolute RPTs.
3.
The difference between the untared upstream
and downstream absolute pressure readings
(upstream – downstream).
value is always in Pascal [Pa].
4.
The flow corresponding to the current untared
differential pressure in the current flow units.
1.
The tare value currently in use [Pa].
2.
The new tare value, resulting from this
execution of the TARE function [Pa].
3.
Microrange tare value currently in use [Pa}
4.
New microrange tare value [Pa].
The tare screen shows the upstream and downstream RPT readings
WITHOUT the current tare applied. The [P&T] screen shows the RPT readings
WITH the tare applied (see Section 3.4.5).
the
two
transducers
Page 42
202.347 kPaa 202.311
T
This differential
OldT:
NewT:
and
alerts
the
36 Pa
0.06 sccm
44Pa
m
20
36Pa
m
20
operator
to
excessive
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