Barrer

The barrer is a non-

• To denote an amount of substance, the 'cm³_STP' is standard cubic centimeter, which is a unit of amount of substance rather than a unit of volume. It represents the number of gas molecules or moles that would occupy one cubic centimeter at standard temperature and pressure, as calculated via the ideal gas law.
• To denote a pressure differential, the notation 'cmHg' is used; a 'centimetre of mercury', which is ten times the more familiar 'millimetre of mercury'.
• And finally, the centimetre and square centimetre are used in the normal way to measure thickness and area.

The

To convert to CGS permeability unit, one must use the following:[1]

${\displaystyle {\rm {{1}\ barrer={M\ \times }\ {3.35\times 10^{-13}}\ {\frac {g\cdot cm}{s\cdot cm^{2}\cdot bar}}}}}$

Where M is the molecular weight of the penetrant gas (g/mol).

Another commonly expressed unit is Gas Permeance Unit (GPU). It is used in the measurement of gas permeance. Permeance can be expressed as the ratio of the permeability with the thickness of membrane.^[2]

${\displaystyle {\rm {{1}\ GPU=10^{-6}\ {\frac {cm_{STP}^{3}}{cm^{2}\cdot s\cdot cmHg}}=7.501\ \times \ 10^{-12}\ {\frac {m_{STP}^{3}}{m^{2}\cdot s\cdot Pa}}}}}$

Or in SI units:

${\displaystyle {\rm {{1}\ GPU=3.35\ \times \ 10^{-10}\ {\frac {mol}{m^{2}\cdot s\cdot Pa}}}}}$

References

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