Fluke HPMS - Manual (Page 41)

3. OPERATION
Page 31 © 2007 DH Instruments, a Fluke Company
Leak check is range specific in the sense that a leak check is run using the active range.
However, only one set of leak check results is maintained in memory and each leak test completed
overwrites the memory. View leak check always shows the results of the last leak check run
regardless of the range that is now active. The results screen includes the range indicator to
indicate the range in which the leak check was run.
3.3.6 [DISPLAY]
 PURPOSE
To select, from a variety of choices, the information that is displayed on the second line of the
RPM4 display.
 PRINCIPLE
RPM4 supports a variety of advanced pressure measurement functions that are displayed on
the second (bottom) line of the RPM4 display. In summary, the available display functions
included are:
AVERAGE Calculates the average measured pressure 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 3.3.6.1). This function is
often used to filter out pressure noise in an unstable system. The magnitude of
the noise is quantified by the standard deviation about the mean. A second Avg
screen allows the instantaneous pressure values to be viewed during an
averaging cycle.
RATE Calculates and displays the current rate of change of pressure in current
pressure units/second (see Section 3.3.6.2). This function is a useful
indication of the stability of the pressure being measured. It is often used as
an indication of positive or negative leak rate and as a go/no go criterion of
when to take data when comparing RPM4 and a device under test, for
example in a calibration. Rate is used by the Ready/Not Ready function to
determine when a Ready condition exists (see Section 3.2.1).
DEVIATION Continuously calculates and displays the difference between the pressure
measured by RPM4 and a target pressure entered by the user (see Section
3.3.6.3). This function is useful in monitoring the evolution of pressure around
and/or away from a desired set point.
RPT Allows pressure measurement from the RPM4’s two Q-RPTs to be displayed
simultaneously (see Section 3.3.6.4).
HI/LO Records and displays maximum and minimum pressures measured (see
Section 3.3.6.5). This function is used to keep track of the minimum and
maximum pressure observed in a system over a period of time or to monitor
if a pressure min/max limit has been exceeded..
FREEZE Captures and displays the pressure measured by the active range of RPM4
when the [ENT] key is pressed (see Section 3.3.6.6). This function is useful
to record the pressure present at the time of an operator observed trigger
event, for example when the needle of an analog gauge is on the nominal
point or when a switch activates.
CLEAN Blanks out the second line of the display (see Section 3.3.6.7). This function
is used when a simple display of pressure measured by the RPM4 active
range with minimal additional information is desired.