Micromeritics Gemini VII 2390a Operator's Manual page 306

Appendix C
The thickness of the remaining adsorbed layer at this relative pressure is calculated:
=
Tw HP1
1
where
HP1, HP2, and HP3 are Halsey Parameters 1, 2, and 3 (respectively) from the Halsey Thickness Equa-
tion dialog.
These calculations illustrate the use of the Halsey thickness equation. If the Harkins/Jura equation was
selected, substitute the following wherever the thickness equation appears:
------------------------------------- -
=
Tw
1
HJ2
where
HJ1, HJ2, and HJ3 are Harkins-Jura Parameters 1, 2, and 3 (respectively) from the Harkins-Jura Thick-
ness Equation dialog.
The following calculations (a-c) are made for each relative pressure interval based on the increment of
volume desorbed during that interval. The variable I refers to the interval number, that is I=1 for the
first interval from Pr
found. K refers to the total number of intervals in which new pores have been found. K is also the num-
ber of lines reported on the BJH table for collected data.
a.) The thickness of the adsorbed layer at the end of the interval is calculated as follows:
=
Tw HP1
+ 1
I
(For the last pressure interval from the lowest Pr
For the first pressure interval, there are no previously opened pores so the volume desorbed
from walls of previously opened pores is zero (Vd
skipped.
The change in thickness of the wall layer due to desorption from previously opened pores is
calculated:
Tw
=
Tw
The annular cross-sectional area of the wall layer desorbed is calculated for all previously
opened pores:
 Rc  
=
CSA
J
C-12
HP3
HP2
------------------ -
 
ln
Pr
1
HJ3
HJ1
 
– log
Pr
1
to Pr , and so on. J refers to each previous interval during which new pores were
1 2
HP3
HP2
-------------------------
 
ln
Pr
+ 1
I
–
Tw
1 + 1
I
2 2 – 16
Tw   10 
+ –
Rc cm
j j
to zero relative pressure, Tw
I
= 0), and the remainder of Step (a) is
1
2 2

/A
Gemini VII
= 0.)
I+1
239-42828-01 - Dec 2012