3. GENERAL OPERATION
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loading 10 kg of mass. However, once all the influences on the measurement are taken into
consideration, the actual mass to load to define exactly 100 kPa will not be 10.00000 kg, it will be
a value near 10 kg such as 9.99731 kg. This value is difficult to load, as it requires relatively
complex mass accounting and the manipulation of very small sub-gram masses. To avoid
handling a difficult, odd mass value, one might instead decide to load 10 kg and use whatever
pressure results as the reference pressure. In this example, loading 10 kg rather than 9.99731
kg would result in defining 100.0269 kPa rather than 100.0000 kPa. The pressure defined is only
very slightly different from the nominal value and there is no additional uncertainty if that value is
used. The savings in time and reduction of possible mass loading errors are significant.
The PG7000 RES function is used to cause PG7000 to automatically calculate mass loads to a
whole number value starting at 0.01 g and increasing in powers of 10 to 0.1 kg. This function is very
useful to make operation more convenient and less error prone when it is not imperative that the
pressure defined by PG7000 be exactly the nominal pressure of the test or calibration sequence.
The mass loading resolution of AMH automated mass handling systems is 0.1 kg. The
default mass loading resolution when AMH is initialized is 0.1 kg. If resolution finer than 0.1 kg is
set when AMH is active, the AMH loads the required mass value wit 0.1 kg resolution and the
operator is prompted with an instruction to load the trim mass under 0.1 kg. For fully automated
operation, the mass loading resolution should always be set to 0.1 kg.
OPERATION
To access the resolution function, press
[RES].
The
display is:
Mass loading rsltn:
0.01 g < and >
Press the
[
←
]
and
[
→
]
keys to select the desired level of resolution.
[
←
]
decreases
resolution and
[
→
]
increases resolution. Press
[ENTER]
to set the selected resolution and
return to the main run screen. The resolution range is from 0.01 g to 0.1 kg in powers of 10.
The RES setting has no affect in
mass to pressure
mode. The RES setting only affects the
resolution of the mass commands that result from pressure entries in
pressure to mass
mode
(see Section 3.9.12).
In PG7000 high line differential pressure mode (see Section 3.9.4.2), line pressures setting
is not affected by the RES setting; line pressures are always set with 0.1 kg resolution.
Differential pressure mass loading resolution is determined by the RES setting.
3.9.11
[ENTER/SET P] FROM RUN SCREEN
PURPOSE
To enter and execute
pressure to mass
or
mass to pressure
commands (see Section 3.9.12).
PRINCIPLE
PG7000 can calculate and display the mass to be loaded to achieve an entered pressure
value (
pressure to mass
mode), or the pressure resulting from an entered mass load (
mass
to pressure
mode). The P
OR
M function is used to set
pressure to mass
or
mass to pressure
mode (see Section 3.9.12).
Pressing
[ENTER/SET P]
from any run screen (MAIN, SYSTEM or AMBIENT) accesses the
pressure or mass entry screen which allows the command value to be entered and proceeds
through the sequence to set or read the pressure defined by PG7000.
