Micromeritics ASAP 2460, Operator'S Manual

Page: 113 / 468

ASAP 2460 Operator’s Manual Analysis Conditions Files
246-42800-01 - Aug 2013 3-19
Target Pressures
Options
button
•
First Pressure Fixed Dose
-
Select this option to have the sample dosed with a specified amount of
gas until the first pressure point is reached. This initial dosing quickly
meets the adsorptive demand of the sample.
The first point on the pressure table is the threshold value. Once this first
pressure point is reached, points are equilibrated and recorded in
accordance with the specified pressure table.
Use this mode if performing a standard nitrogen analysis of microporous
or highly mesoporous materials such as catalysts. If the first pressure
table point is low, and the gas uptake of the sample is expected to be
high, choosing this mode can shorten the time required to reach the first
point on the pressure table.
•
Maximum volume increment
-
Select this option to specify when additional data points are to be
collected between target pressures in regions of high adsorption. When
the maximum increment has been adsorbed since the last collected data
point, another point is equilibrated and collected.
When using this option, reaching pressure points exactly is not
important; therefore, the tolerances should be set relatively large

(10 mmHg and 10% or so) for proper functioning of the algorithm. The
pressure table should also have several points scattered over the region
of interest.
During desorption, this field is treated as a maximum volume
“decrement” value.
Field or Button Description (continued)