DH Instruments COMPASS FOR MOLBOX, User Manual

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COMPASS

for molbox™ User’s Manual
Page 209
© 1998-2003 DH Instruments, Inc .
Stability Limit A limit expressed in units of flow per second (e.g., sccm/second). The stability limit is
used as the molbox
Ready/Not Ready criterion Ready ( <*> ) if rate is less than stability
limit, Not Ready ( <
↑
> or <
↓
> ) if rate is greater than stability limit. See also Rate .
Surrogate Gas
A gas whose behavior, from the standpoint of a device under test (DUT), is similar to
the process gas for which the device is to be characterized and used. A surrogate gas
is often used in calibration and testing when the process gas cannot be used for safety
or cost reasons. A DUT gas conversion factor (“K” factor) is used to convert from the
surrogate gas to the process gas.
System
Configuration A listing of the specific hardware items that COMPASS uses by default to perform
various data acquisition and control functions. The System Configuration is made up
of individual Hardware Definitions.
Tare “Zeroing” of the molbox pressure transducers at the upstream or downstream pressure
to eliminate the zero error in the measurement of the differential pressure across a
molbloc. molbox1 and molbox RFM have automated taring routines and
COMPASS
can cause these to execute during a test. See the molbox Operation and Maintenance
Manual,
[Tare] Section.
Test Definition A database record which defines all the aspects of a test procedure that COMPASS
can run on a DUT. Test Definitions are associated with DUTs and control the test
procedure when a test is run.
Test Gas The gas flowing through the molbloc that is being used to run the test or calibration.
The test gas, from the standpoint of the device under test, could be a surrogate gas or
the process gas.
Tolerance Same as DUT tolerance.
Upstream Location of point A relative to point B in a flow system in which point A is at a different
location in the reverse direction of the flow. For example, the upstream molbloc
pressure port is upstream relative to the downstream pressure port because it is at a
different location from the downstream port in the opposite direction of the flow.
Volume Flow Units
Units of measure of volume flow (sometimes called “actual flow”). Do not confuse
volume flow units with volumetrically based mass flow units. See the molbox Operation
and Maintenance Manual,
[Unit] Section, for an extensive discussion of flow units of
measure.