Micromeritics ACCUPYC II 1345 - C Sample Volume Equation Derivation C

C SAMPLE VOLUME EQUATION DERIVATION
10, 100, AND 350 CM
3
UNITS
The AccuPyc II is a gas displacement pycnometer which measures the volume of solid objects of
irregular or regular shape whether powdered or in one piece. A greatly simplified diagram of the
instrument is shown below.
Sample volume is determined from the known cell and expansion volumes and from measured
pressures.
The cell and expansion chamber are initially at ambient pressure and the valve is closed. The cell is
then charged to an elevated pressure.
The ideal gas law gives:
(1)
where
n
c
= moles of gas in the sample cell
R = the gas constant
T = temperature
V
c
= cell volume
V
s
= sample volume
V
x
= expansion volume
P
1
= initial cell pressure
Expansion volume:
(2)
C Sample Volume Equation Derivation
AccuPyc II 1345 Operator Manual
134-42851-01 (Rev A) — Jan 2021
C - 1