Micromeritics ACCUPYC III Operator's Manual page 54

2 About the Software
Method (continued)
Selections
Use Vacuum
Preparation
Purge Fill Pressure
Cycles
Cycle Fill Pressure
Pressure
Stabilization
Equilibration Rate
2 - 24
Description
A vacuum preparation will evacuate the sample chamber, pressurize to
roughly atmospheric pressure, and then evacuate again. Using a
vacuum system can help remove contaminates from samples that
purging might not be able to.
When selected, vacuum preparation cycles are performed instead of
purges when analysis starts. The number of vac prep cycles is equal to
the value in the Purges field. For example, if five purges are selected,
and Use Vacuum Preparation is selected, five vacuum preparation
cycles are run.
A vacuum pump must be attached and powered on before
running an analysis with a method that uses vacuum pre-
paration.
Enter the fill pressure. For most applications, the default of 19.500 psig
(134.45 kPag) is adequate. Typically, the greater the fill pressure, the
easier it is to measure the volume precisely. However, a lower pressure
may be required for some samples to obtain results that do not impact
volume or density results.
Enter the number of cycles to be performed. A cycle is a series of instru-
ment operations, which produce a single volume measurement.
Enter the fill pressure. For most applications, the default of 19.500 psig
(134.45 kPag) is adequate.
The instrument obtains density from the volume calculated from
measuring pressure differences. Allowing the pressure to stabilize
before moving on is a crucial step in achieving precise and repeatable
results.
Specify if equilibrate should be by Time (wait the specified number of
seconds as set in the Interval field) or by Rate (wait until the pressure
rate of change is less than the specified rate as set in the Equilibration
Rate field).
If equilibrate by Time is selected, the instrument will only equilibrate by
time for elevated pressures. Equilibration at atmospheric pressure is
always by rate. A fixed time interval moves on to the next step when the
specified time has been reached.
Enter the rate. The pressure measurement will end when the entered
rate is obtained. A high rate will produce faster results, but with lower
precision. The lowest rates may cause errors when some materials
(such as those with appreciable vapor pressures or organics) are
AccuPyc III Operator Manual
135-42800-01 (Rev -) — Nov 2023