Micromeritics ASAP 2460 - Page 344

Appendix C ASAP 2460 Operator’s Manual
C-20 246-42800-01 - Aug 2013
Pore diameters and radii are adjusted for the change in thickness of the adsorbed wall
layer during this interval. If new pores were opened during this interval, the average
diameter is adjusted by the change in layer thickness during the second portion of the
desorption interval as:
The layer thickness change during the whole interval is added to diameters of previ-
ously opened pores as:
(not including) D
avg,k
)
The layer thickness change desorbed during this interval also is added to the radii cor-
responding to the ends of the pressure intervals as:
for all except Rc
k+1
.
Steps a to c are repeated for each pressure interval.
After the above calculations have been performed, the diameters corresponding to the
ends of the intervals are calculated as:
for all Rc
j
including Rc
k+1
.
The remaining calculations are based on Dp
i
, D
avg,i
, and LP
i
. These calculations are
only done for D
avg,i
values that fall between the Minimum BJH diameter and the Max-
imum BJH diameter specified by the operator on the BJH Adsorption Report
Options window or the BJH Desorption Report Options window.
(1.) Incremental Pore Volume (Vp
i
, cm
3
/g):
(2.) Cumulative Pore Volume (Vp
cum,i
, cm
3
/g):
D
avgknew
D
avg k old
2 Td+=
D
avgknew
D
avg k old
2 Tdw+=
Rc
jnew
Rc
jold
Tw+=
Dp
j
2 Rc
j
=
Vp
i
 Lp
i

D
avg i
2
---------------
2
10
16
cm
2
Å
2
---------------------
=
VP
cum i
Vp
j
for J 1
j

=