Thermal Transpiration Correction - Micromeritics ASAP 2020 Confirm Operator's Manual

Appendix C

Thermal Transpiration Correction

During data reduction, thermal transpiration correction is applied to the data if the user
selected Thermal transpiration correction from the Report Options dialog. Starting with the
first collected pressure, the following calculations are performed until the pressure ratio (PC/
P) is greater than or equal to 0.99.
Y =

=
F =
PC
where:
P
SD
MD
T


G
H
T
ABT
T
RM
PC
F,Y,
202-42811-01 - Mar 2011
2
 
P SD MD
3

-----------------------------------
10

2.33 T

1 + G Y
---------------------- -

1 + H Y
1
----------------------------------------------------- -
2
      Y   
Y + +


T 0.5
 
ABT
 ----------
= 1 – F – F

 
T


RM
= equilibrated collected pressure measured by gauge at temp
T (mmHg)
RM
= inside diameter of sample tube (mm), from the Report Options
dialog
= thermal transpiration hard sphere diameter of gas (Å), from
the Adsorptive Properties dialog
= average temperature [T
= Weber's coefficient, 0.033
= Weber's coefficient, 0.245
= Weber's coefficient, 2.5
= Weber's coefficient, 2
= analysis bath temperature (K), from the Po and Temperature Options
dialog
= room temperature (298 K)
= corrected equilibrated pressure at temperature T
= intermediate values for subsequent calculations



P



+ T ] / 2 (K)
ABT RM
ASAP 2020 Confirm
(mmHg)
ABT
C-7