DH Instruments COMPASS FOR MOLBOX, User Manual

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COMPASS

for molbox™ User’s Manual
Page 207
© 1998-2003 DH Instruments, Inc .
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Absolute As in “absolute pressure”. Pressure expressed relative to vacuum.
Actual Flow Units Units of measure of volume flow (sometimes called “volume 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.
Averaging Time The time over which reference and DUT readings are taken at a flow point in a
COMPASS run mode. COMPASS makes as many readings as possible during the
averaging time and then averages the readings to arrive at the reference and DUT
reading for the flow point.
Calibration Gas
The gas with which a DUT is normally calibrated. The calibration gas may be a
surrogate gas for the process gas (see also surrogate gas and process gas).
Cycle (Test Cycles) A complete set of flow points in a COMPASS test run. Tests may include multiple
cycles. Number of cycles is set in the Test Definition [Sequence] tab .
DAQ The short form of Data Acquisition. This refers to the method used to gather data from
a DUT.
Data File (*.dat) Files automatically created by COMPASS to store the data from a test.
DMM Digital multimeter. Used by COMPASS to read the electrical outputs of DUTs.
Downstream Location of point A relative to point B in a flow system in which point A is at a different
location in the direction of the flow. For example, the downstream molbloc pressure
port is downstream relative to the upstream pressure port because it is at a different
location from the upstream port in the direction of the flow.
DUT Device Under Test, Test Instrument (TI), Unit Under Test (UUT). The device that is
being tested using
COMPASS . DUTs are defined in DUT Definitions.
DUT Definition The record in the DUT database in which COMPASS stores DUT information. Defines
the DUTs that are tested by COMPASS .
DUT Profile A type of DUT Definition that is intended to define a type of DUT. This is a generic
definition that does not include serial number or ID. Can be used to test any DUT of a
specific type. See also Individual DUT.
DUT Tolerance The performance limit of a DUT expressed in terms of maximum allowable
disagreement with the flow reference. DUT tolerance may be expressed in flow units,
as a % of DUT FS, as a % of reading or as a combination.
Dwell A waiting period at a flow point between the time the flow has been set and stabilized
and the start of data acquisition to take the DUT and reference readings at the flow point.
Error The disagreement between the DUT indication and the flow measured by the reference
at a flow point. The error is always calculated using (DUT – reference).
FS Abbreviation of “full scale”. The full scale value is the maximum value or the span of a
measurement range. Limits and specifications are often expressed as % FS.
Hardware Definition The record in the hardware database of a specific hardware item available for use
by
COMPASS. The Hardware Definition defines the piece of hardware including
manufacturer, serial number ID and interfacing details. Hardware Definitions are
selected to put together the System Configuration that
COMPASS uses to run tests.
Individual DUT A type of DUT Definition that is intended to define a specific DUT including its serial
number and ID. Individual DUT Definitions can only be used to test one specific DUT.
See also DUT Profile.