™/S, MOLBLOC TERMINAL OPERATION AND MAINTENANCE MANUAL
© 1995 - 2010 Fluke Corporation, DH Instruments Division
Page 72
Note
To change the pressure and/or temperature unit of measure,
see Sections 3.5.8 and 3.5.9.
3.4.6
[DISPLAY]
PURPOSE
To select, from a variety of choices, the information that is displayed on the second line of the
display. Averaging is one of the choices.
PRINCIPLE
supports a variety of ADVANCED FLOW MEASUREMENT functions that are
displayed on the second (bottom) line of the display. In summary, the available
DISPLAY functions included are:
RATE
:
Calculates and displays the current rate of change of flow in current flow
units/second (see Section 3.4.6.1). This function is a useful indication of the
stability of the flow being measured. It is often used as an indication of positive
or negative leak rate and as a “go/no go” criterion for when to take data when
comparing and a DUT (e.g., in a calibration).
AVERAGE
: Calculates the average flow measurement over a user specified period of time
and displays the average, the standard deviation about the mean and a
countdown in seconds to the next average (see Section 3.4.6.2). This function
is often used to filter out flow noise in an unstable system or to gather a
corresponding sample when comparing molbloc/molbox measurements to
another device with a long integration time (e.g., a volumetric flow standard).
The magnitude of the noise is quantified by the standard deviation about the
mean. A second screen allows the instantaneous flow values to be viewed
during an averaging cycle.
HI/LO
:
Records and displays the maximum and minimum flows measured since HI/LO
reset (see Section 3.4.6.3). This function is used to keep track of the minimum
and maximum flow observed over a period of time or to monitor whether a flow
min/max limit has been exceeded.
TOTAL
:
Totalizes the mass or volume flowed over a period of time (see Section
3.4.6.4). Used to measure total mass or volume over a period of time. Can be
useful in calibration or verifying a totalizing flow device, when comparing
molbloc/molbox to a gravimetric standard or to add or remove a specific
quantity of mass or volume from a system.
UNIT
:
Displays the measurement of flow through the molbloc simultaneously in a
second flow unit (see Section 3.4.6.5). This function is convenient when
working with an unfamiliar flow unit of measure to simultaneously display a
familiar unit or any time a real time flow unit conversion is desired.
DEVIATION
: Continuously calculates and displays the deviation between the current flow
measured by and a target flow defined by the user (deviation =
current flow - target) (see Section 3.4.6.6). This function is useful in monitoring
the evolution of flow around and/or away from a desired set point.
FREEZE
:
Captures and displays the instantaneous flow value measured by
when the
[ENTER]
key is pressed (see Section 3.4.6.7). This function is useful
to record the flow present at the time of an operator observed trigger event.
CLEAN
:
Blanks out the second line of the display (see Section 3.4.6.8). This function is
used when a simple display of flow measured by the , without
additional information, is desired.
