Calculations - Micromeritics ASAP 2460 Operator's Manual

Appendix C

Calculations

The quantities adsorbed (Qa) are converted to the liquid equivalent volumes (Vl, cm
------------------------------------ -
Vl =
i
22414cm
where V is the liquid molar volume from the fluid property information.
mol
The relative pressure (P
ple are filled.
The corresponding Kelvin core radius is calculated. Only pores smaller than this size will be included:
---------------------------------
Rc =
i 
1 +
where
A =
F =
Rc =
This radius will be adjusted for the thickness of the adsorbed layer during subsequent calculation steps.
The following calculations (a-c) are made for each relative pressure interval based on the increment of
volume desorbed during that interval:
where
i =
j =
k =
C-16
Q V
i mol
3
STP
) is assumed to be close to unity so that substantially all the pores in the sam-
i
– A
  
F ln P
i
adsorbate property factor (from the BJH Adsorptive Options window)
fraction of pores open at both ends (from the BJH Adsorption Report
Options window or the BJH Desorption Report Options window); assumed
to be zero for desorption
Kelvin radius (Å) of core
interval number, that is i=1 for the first interval from P
each previous interval during which new pores were found
the total number of intervals in which new pores have been found. It is also
the number of lines reported on the BJH table for collected data
ASAP 2460 Operator's Manual
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/g):
to P , and so on
1 2
246-42800-01 - Aug 2013