Micromeritics ASAP 2460, Operator'S Manual

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Appendix C ASAP 2460 Operator’s Manual
C-18 246-42800-01 - Aug 2013
b.) The physical processes occurring for this pressure interval are determined as:
(1.) If Vd
i
is greater than the current increment of volume desorbed ( Vl
i
- Vl
i+1
), desorption
from walls only is occurring. Total surface of walls exposed thus far (cm
2
/g) is calcu-
lated as:
for all previously opened pores
where
D
avg,j
= weighted average pore diameter calculated in Step b(2).
A new layer thickness (

Tw ) that will not overcompensate for the actual volume
desorbed in this interval is calculated:
Since no cores are evaporated in this pressure interval, no new pores are revealed.
Thus no ending Kelvin radius and average pore diameter are calculated for this inter-
val. Note that this means the report may have fewer tabulated intervals on the
collected data report than experimental pressure intervals.
(2.) If Vd
i
is less than the volume increment desorbed during this interval ,
the remaining volume is due to new pores with core evaporation taking place in this
interval.
K , the number of intervals with new pores exposed, is increased by 1. (For the
interval from the lowest Pr
1
to zero relative pressure, no new pore volume is calculated
and the rest of Step b is skipped.)
The volume desorbed from newly opened pores in this interval is calculated as:
The Kelvin radius for the end of the interval is calculated as:
SA
w

LP
j
 
D
avg j ,
 
10
8 –
cm
Å
--------------------
 
 
j

=

Tw
Vl
i
Vl
i 1 +
–
 
10
8
Å
cm
-------
 
 
SAw
i
--------------------------------------------------------
=
Vl
i
Vl
l 1 +
–
 
Vc
i
VI
i
VI
i 1 +
–
 
Vd
i
– =
Rc
k 1 +
A –
1 F +
 
P
i 1 +
 
ln
----------------------------------------
=