Micromeritics ASAP 2460 Operator's Manual page 304

Appendix B
4039- The isotherm does not meet the constraints of the Cheng/Yang assumption.
Cheng/Yang correction will not be applied.
Cause:
Action A:
Action B:
4040- The value of Qm computed from the Langmuir equation is too low. The pore
size will not be computed for all data points.
Cause:
Action:
B-24
The Cheng/Yang correction to the Horvath-Kawazoe equation requires
the value of the monolayer volume as calculated from the Langmuir
equation. The isotherm does not correlate to the Langmuir assumption
with a coefficient of 0.98 or more. The correction is not applicable to
this isotherm or to the range of the data points selected.
The analysis will be performed without the Cheng/Yang correction.
Deselect Apply Cheng/Yang correction on the Horvath-Kawazoe
Report Options dialog to prevent this message from appearing on
future reports.
Generate the Langmuir report for the same data points selected for the
Horvath-Kawazoe report. If the Langmuir correlation coefficient can
be brought above 0.98 by removing some points at high relative pres-
sure, remove them and reproduce the Horvath-Kawazoe reports.
The Cheng/Yang correction to the Horvath-Kawazoe equation requires
the value of the monolayer volume as calculated from the Langmuir
equation. The computed value is less than the volume adsorbed at the
largest relative pressure included in the analysis. The correction is not
applicable to this isotherm or to the range of the data points selected.
The analysis will be performed and the Cheng/Yang correction will be
applied to all points with a volume adsorbed less than the value of Vm.
The pore size will not be calculated for data points with an invalid vol-
ume adsorbed. Deselect Apply Cheng/Yang correction on the Horvath-
Kawazoe Report Options dialog to clear this message.
ASAP 2460 Operator's Manual
246-42800-01 - Dec 2013