Micromeritics TriStar II 3020 - Thermal Transpiration Correction

TriStar II 3020 Appendix C
302-42828-01 - Dec 2012 C-5
Thermal Transpiration Correction
Y
PSDMD
2

2.33 T
------------------------------------
10
3
=

1 GY+
1 HY+
-----------------------
=
F
1
 Y
2
Y++
------------------------------------------------------
=
PC 1 FF
T
ABT
T
RM
------------


0.5


––



P=
During data reduction, thermal transpiration correction is applied to the data if the user selected Ther-
mal 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.
where:
P
= equilibrated collected pressure measured by gauge at temp T
RM
(mmHg)
SD = inside diameter of sample tube (mm), from the Report Options dialog
MD = thermal transpiration hard sphere diameter of gas (Å), from the Adsorptive
Properties dialog
T = average temperature [T
ABT
+ T
RM
] / 2 (K)
 = Weber’s coefficient, 0.033
 = Weber’s coefficient, 0.245
G = Weber’s coefficient, 2.5
H = Weber’s coefficient, 2
T
ABT
= analysis bath temperature (K), from the Po and Temperature Options dialog
T
RM
= room temperature (298 K)
PC = corrected equilibrated pressure at temperature T
ABT
(mmHg)
F,Y, = intermediate values for subsequent calculations