Micromeritics TriStar II 3020 - Page 322

D
avg
K
2Rc
K
Rc
K 1+
+Rc
K
Rc
K 1+

Rc
K
2
Rc
K 1+
2
+
------------------------------------------------------------------------------------
=
P
avg
K
1– 2A–
1 F+D
avg
K

-------------------------------------
ln=
Tw
avg
K
HP1
HP2
P
avg
K
ln
------------------------
HP3
=
Td Tw
avg
K
TW
I 1+
–=
CSAc
K
Davg
K
2
-----------------
Td+
2
10
16–
cm
2
/A
2
=
LP
K
Vc
I
CSAc
K
-----------------
=
D
avg
Knew
D
avg
Kold
2 Td+=
D
avg
Jnew
D
avg
Jold
2  Tw+=
Appendix C TriStar II 3020
C-14 302-42828-01 - Dec 2012
weighted average pore diameter and a corresponding length sufficient to account for
the required volume of adsorbate. The weighted average pore diameter is calculated as
follows:
D
avgK
is the diameter of a pore which would have a surface area that is the average of
the areas for pores radius Rc
K
and Rc
K+1
, if its length was the mean of the lengths at
those radii.
The relative pressure corresponding to D
avgK
is calculated as follows:
The thickness of the adsorbed layer at this pre
ssure is calculated as follows:
The decrease in thickness of the wall layer by desorption from the walls of new pores
du
ring the lower portion of the pressure interval is calculated as follows:
The cross-sectional area of the newly opened pore
s is calculated as follows:
The length of the newly opened pores
is calculated as follows:
c.) Pore diameters and radii are adjusted for the ch
ange 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 follows:
The layer thickness change during the whole interval is added to diameters of previously
opened
pores as follows: