Micromeritics ASAP 2460, Operator'S Manual

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Appendix C ASAP 2460 Operator’s Manual
C-4 246-42800-01 - Aug 2013
Free Space
Measured
Measured free-space volumes are calculated using the following equations:
where:
P
1
= system manifold pressure before dosing helium onto sample
P
2
= system manifold pressure after dosing helium onto sample
P
3
= sample pressure after raising dewar and equilibrating with helium
T
amb
= approximate room temperature (298 K)
T
bath
= analysis bath temperature ( K )
T
man
= system manifold temperature before dosing helium onto sample ( K )
T
STD
= standard temperature (273.15 K)
V
bath
= portion of cold free space at analysis bath temperature
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
man
= manifold volume (cm
3
)
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
------------
–
----------------------
=