Micromeritics Gemini VII 2390a, Operator'S Manual

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Gemini VII Appendix C
239-42828-01 - Dec 2012 C-5
Thermal Transpiration Correction
Y
P SD MD
2
 
2.33
T

------------------------------------ 10
3

=

1
G Y

+
1
H Y

+
-----------------------
=
F
1

Y
2
   
Y
   
+ +
------------------------------------------------------
=
PC
1
F F
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