Micromeritics ASAP 2460, Operator'S Manual

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Appendix C ASAP 2460 Operator’s Manual
C-26 246-42800-01 - Aug 2013
where
Δ V
p
= Change in pore volume
A
p,i
= Pore surface area
A
p,i,cum
, l
i,cum =
Summations over the lengths and areas calculated so far
C
v
= Volume correction factor
D = Density conversion factor
= Average Kelvin radius
= Average thickness
Horvath-Kawazoe
A relative pressure lower limit is determined such that L-d
0
never equals zero. All pressure points less
than this limit are discarded. For each collected relative pressure point, values of L are chosen in an
iterative manner, and the relative pressure ( P/Po ) determined by solving one of the following
equations:
• Slit Pore Geometry (original Horvath-Kawazoe)
• Cylinder Pore Geometry (Saito/Foley)
• Sphere Pore Geometry (Cheng/Yang)
Slit Pore Geometry (original HK)
When you use the original Horvath-Kawazoe
9
method, the following equation is solved for each value
of P . The value of L is determined when the solved-for relative pressure is within 0.1% of the collected
absolute pressure.
where
10
32
= the number of cm
4
that are equal to Å
4

= gas solid nuclear separation at zero interaction energy (Å),
d
0
=
where:
D
A
= molecular diameter (Å) from the
Horvath-Kawazoe Physical Proper-
ties
window
D
s
= diameter of sample atom (Å) from the
Horvath-Kawazoe Physical
Properties
window
r
k
t
P
Po
------- ln
K
RT
-------
IP 10
32


4
L 2 d
0
–
------------------------

4
3 L d
0
–
3
--------------------

10
9 L d
0
–
9
--------------------
–

4
3 d
0
3
----------
–

10
9 d
0
9
----------
+ =
Z
S
Z
A
+
2
-------------------
D
A
D
s
+
2
--------------------