DH Instruments COMPASS FOR MOLBOX, User Manual

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COMPASS

for molbox™ User’s Manual
© 1998-2003 DH Instruments, Inc .
Page 44
Figure 22. <molbox Output> Run Screen
Table 10. <molbox Output> Run Screen Fields
LABEL DESCRIPTION
Red/Green Circle Molbox flow Ready/Not Ready indicator (see the molbox Operation and Maintenance
Manual, Ready/Not Ready Section). The circle is green when molbox flow is ready
and red when not ready.
Rate Instantaneous molbox flow rate of change in unit of flow per second.
Flow Molbloc flow. This value is the direct, unmanipulated output of the molbox in all run
modes except
[Run molbox] . In [Run molbox], the flow unit can be selected and
the molbox output is converted to the currently selected flow unit. In all operating
modes, except
[Run molbox] , the flow units available for this display are limited to
the basic mass flow (mass/time) units. These are the base units COMPASS uses for its
calculations.
Reynolds Number Reynolds number of the flow through the molbloc as calculated by the molbox.
Upstream Pressure Pressure read by the molbox upstream pressure transducer.
Downstream
Pressure
Pressure read by the downstream molbox pressure transducer.
Differential Pressure The pressure drop across the molbloc that is currently being used by the molbox to
calculate flow.
The differential pressure is the difference between the molbox upstream and
downstream RPTs (in molbox RFM, it may be the measurement made by the
microrange RPT). The molbox determines the differential pressure and outputs it to
COMPASS .
BPR BPR is the back pressure ratio, downstream pressure/upstream pressure. This field
is present only when the reference is a molblocS. The value displayed is either the
measured ratio or N/A when the value is not measured. The molbox front panel BPR
setting determines whether or not BPR is measured or if the 2 molbox RPTs are
averaged. Refer to the molbox operation and maintenance manual for
Temperature Molbloc temperature as measured by the molbox from the average of the molbloc
upstream and downstream PRT’s.
Set Active molbox flow set point. This value is used only in [Run molbox] mode if the
molbox is equipped with the MFC control option. Change the setting using the flow
control toolbar icon (see Section 6.6.8).
Output Active molbox output. As with the <Set> , this value is used only in [Run molbox]
mode if the molbox is equipped with the MFC control option.
Switchbox Molbox MFC switchbox control and measurement channels. The format is <Set
Channel . Measurement Channel> . This field has no value if the molbox does not
have the MFC control option and an MFC switch box is not in use. Use the flow
control icon in
[Run molbox] mode to change the current channel.
K Factor Active DUT gas conversion value in use by the molbox. In [Run molbox] mode, this
value can be changed using the flow conditions toolbar icon (see Section 6.6.5). In all
other run modes, the active DUT determines the K factor. In this case, the value
cannot be changed. See the molbox Operation and Maintenance Manual, K Factor
Section, for details on the use of K factors.