Micromeritics TriStar II 3020 - Free Space

Appendix C TriStar II 3020
C-2 302-42828-01 - Dec 2012
P
rel
I
= relative pressure for the I
th
data point (mmHg)
P
I
= absolute pressure for the I
th
data point, taken at equilibrium (mmHg)
Quantity Adsorbed Calculations
Free Space
V
FW
V
MAN
T
MAN
--------------
P
1
P
2
------
1– T
STD
=
V
FC
V
FW
P
2
P
3
------


=
V
BATH
V
FC
V
FW
–
1
T
BATH
T
AMB
---------------
–
--------------------------
=
Measured
Measured free-space volumes are calculated using the following equations:
where:
P
1
= system manifold pressure before dosing helium onto sample (mmHg)
P
2
= system manifold pressure after dosing helium onto sample (mmHg)
P
3
= sample pressure after raising Dewar and equilibrating with helium (mmHg)
T
STD
= standard temperature (273.15 K)
T
AMB
= approximate room temperature (298 K)
T
MAN
= system manifold temperature before dosing helium onto sample (K)
V
MAN
= manifold volume (cm
3
)
V
FC
= volume of free space, cold (cm
3
at standard temperature)
V
FW
= volume of free space, warm (cm
3
at standard temperature)
V
BATH
= portion of cold free space at analysis bath temperature: used in non-ideality
correction (cm
3
at standard temperature)
T
BATH
= analysis bath temperature (K)