3. GENERAL OPERATION
Page 89
© 1998-2008 DH Instruments, a Fluke Company
The setting of the RES function has no effect on the resolution of mass load
entries in
mass to pressure
mode (see Section 3.9.10).
The
mass to pressure
mass entry is expressed in nominal mass while the
MAIN run screen displays the true mass loaded. For this reason, the nominal mass
loading instruction and the true mass displayed in the main run screen are slightly
different values. This is normal operation (see Section 3.6).
3.9.11.3
COMMANDS FOR ZERO PRESSURE, ENDING A TEST
Entering a value of zero as the target presure is a convenient way to end a test
and vent the automated pressure control component when AutoGen is ON.
Entering a value of zero in
pressure to mass
mode causes the following
sequence to occur:
Stop piston rotation if AutoRotate is ON.
Vent pressure control component if AutoGen is ON or prompt operator to vent.
A special run screen displays reflecting that the PG7000 is at rest and the
mass loading bell may not be installed. The display is:
1.
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in ready/not ready indicator positions as
status of piston is unknown since mass loading
bell may not be installed.
2. Unknown pressure except in absolute by
atmosphere measurement mode in which the
current value of atmospheric pressure is
displayed. This is the value of absolute by
atmospheric pressure when the system is
vented.
3.
Unknown/meaningless mass load.
4.
Unknown/meaningless piston position.
???----- psi a
--- mm --------kg
3.9.12
[P
OR
M]
PURPOSE
To select between PG7000
pressure to mass
or
mass to pressure
operation mode.
PRINCIPLE
Piston gauges are generally used either to define desired pressure set points (e.g. when
applying reference pressures to a device to be calibrated) or to measure a static pressure
(e.g. when performing a crossfloat intercomparison with another piston gauge).
PG7000s support these two typical situations with two operating modes:
pressure to mass
and
mass to pressure.
In
pressure to mass
operating mode, the operator enters target pressure values and the
PG7000 provides instructions of the mass to load to achieve the desired target pressure.
In
mass to pressure
operating mode, the operator enters the mass currently loaded and the
PG7000 determines the pressure resulting from the current mass load.
Mass to pressure
mode
is also useful to determine the true mass resulting from a nominal mass load (see
Section 3.6).
The P
OR
M function is used to set the PG7000 operating mode to either pressure to mass or
mass to pressure.