Micromeritics Gemini VII 2390a Operator's Manual page 308

Appendix C
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
avg
D
avgK
the areas for pores radius Rc
those radii.
The relative pressure corresponding to D
P
avg
The thickness of the adsorbed layer at this pressure is calculated as follows:
Tw
avg
The decrease in thickness of the wall layer by desorption from the walls of new pores
during the lower portion of the pressure interval is calculated as follows:
Td
The cross-sectional area of the newly opened pores is calculated as follows:
CSAc
The length of the newly opened pores is calculated as follows:
LP
K
c.) 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 follows:
=
D
avg
Knew
The layer thickness change during the whole interval is added to diameters of previously
opened pores as follows:
=
D
avg
Jnew
C-14
2   Rc   Rc 
+
Rc
+ 1
K K K
----------------------------------------------------------------------------------- -
=
2
K +
Rc Rc
+ 1
K K
is the diameter of a pore which would have a surface area that is the average of
K
– 2A
1 –
------------------------------------ -
= ln
  D  
1 +
F
K
avg
K
HP3
HP2
----------------------- -
=
HP1
 
ln
P
K
avg
K
= –
Tw TW
+ 1
avg I
K
2
Davg
– 16
K
---------------- - Td 
= + 10
2
K
Vc
I
---------------- -
=
CSAc
K
2 Td  
+
D
avg
Kold
2   Tw 
+
D
avg
Jold
 Rc  
+ 1
K
2
and Rc , if its length was the mean of the lengths at
K+1
is calculated as follows:
avgK
2 2

/A
cm
Gemini VII
239-42828-01 - Dec 2012