™/S, MOLBLOC TERMINAL OPERATION AND MAINTENANCE MANUAL
© 1995 - 2010 Fluke Corporation, DH Instruments Division
Page 110
In Auto mode, in the BPR OFF valve state:
cannot monitor BPR, but based on the proximity of the most recently measured
BPR to the calculated BPR limit, if the current flow value changes enough that it is likely that
the BPR is approaching the limit, switches to BPR ON valve state to check BPR
directly. It is highly unlikely that valve switching will occur during critical flow measurements
because, typically, high precision flow measurements are not made when flow is changing.
In Auto mode, when the valves are in BPR OFF state, flow is calculated from the average of
the two RPT pressure readings as in BPR OFF mode. When the valves switch to
the BPR ON valve state in Auto mode, the tare can no longer be dynamically calculated
because the two RPTs are not measuring the same pressure. The most recent tare that was
automatically calculated during the BPR OFF valve state is used to correct the pressures
used and displayed in Auto mode until the valves return to the BPR OFF state again. This assures
that flow measurements remain as consistent as possible during Auto mode valve switching
and that the tare value that is most likely to be correct is used at all times.
Note
•
It is possible to change the BPR mode by remote communication with
and also to disable valve control and switching while
in any BPR mode (see Section 4.3.4.2).
•
It is not possible to operate A_B modes when the active BPR mode is Auto
due to internal valving conflicts. denies access to the A_B
modes if the current BPR mode is Auto and does not allow the user to
select Auto mode when an A_B mode is active (see Section 3.5.4).
