Micromeritics ASAP 2020 Confirm Operator's Manual page 367

Appendix C
The thickness of the remaining adsorbed layer at this relative pressure is calculated:
Tw
where
HP1, HP2, and HP3 are Halsey Parameters 1, 2, and 3 (respectively) from the Halsey Thick-
ness Equation 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
where
HJ1, HJ2, and HJ3 are Harkins-Jura Parameters 1, 2, and 3 (respectively) from the Harkins-
Jura Thickness 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 num-
ber, that is I=1 for the first interval from Pr
interval during which new pores were found. K refers to the total number of intervals in
which new pores have been found. K is also the number 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
(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
of Step a is skipped.
The change in thickness of the wall layer due to desorption from previously opened
pores is calculated:
Tw
202-42811-01 - Mar 2011
HP3
HP2
------------------
= HP1
1  
ln Pr
1
HJ3
HJ1
------------------------------------- -
=
 
HJ2 – log Pr
1
HP2
----------------------- -
= HP1
I + 1  
ln Pr
I + 1
= Tw – Tw
1 I + 1
to Pr , and so on. J refers to each previous
1 2
HP3
to zero relative pressure, Tw
I
ASAP 2020 Confirm
= 0.)
I+1
= 0), and the remainder
1
C-15