Micromeritics ASAP 2020 Confirm Operator's Manual page 328

ASAP 2020 Confirm
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:
4041- Cheng/Yang correction is inappropriate for some P/Po.
Cause:
Action:
4042- 0.0 cannot be a starting or ending pressure for a geometric progression from
low pressure.
Cause:
Action:
B-34
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.
The Cheng/Yang correction is usually inappropriate for any P/Po above
the isotherm knee. In some instances, the computed pore sizes may
decrease above the knee. While it is possible to include these relative
pressures (usually above 0.1 P/Po) in the analysis, the computed pore
sizes for these pressures are usually meaningless.
Change the data points selected for the Horvath-Kawazoe report to
include only relative pressures at or below the knee of the isotherm, or
change the Horvath-Kawazoe report options so that the Cheng/Yang
correction is not applied.
You selected to generate a pressure table from a geometrically pro-
gressing range.
Change the 0.0 entered value.
Appendix B
202-42811-01 - Mar 2011