Talk:Permeation

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Units in Simple Approximation

Is there any reason why the units are described as being 'American' rather than 'Imperial' or 'European' rather than SI? —Preceding unsigned comment added by ClimberTom (talk • contribs) 16:36, 5 May 2010 (UTC)[reply]

I think this article should explain the measurement of permeation rate in mol･m/m2･s･Pa, as used in various ANSI standards. --Westwind273 (talk) 00:10, 23 March 2012 (UTC)[reply]

There are two distinct definitions of permeability relating to gas transport. Permeability through porous solids by fluid flow, as governed by Darcy's law, is measured in m^2. Permeability through diffusion of gas in solids, as governed by Fick's law, is measured in SI units of mol･m/m2･s･Pa or mol･/m･s･Pa (cancelling the meter term). This article incorrectly links to intrinsic permeability as defined by Darcy's law. The units of m^2 for permeability are for Darcy's law and are incorrect. The book Whittington's Dictionary of Plastics, Third Edition By James F. Carley (https://books.google.ie/books?id=791DhiI-D88C&pg=PA353&lpg=PA353&dq=darcy+mol+m+s+pa&source=bl&ots=tybSucKvuF&sig=I_P1p4OT03qtsCXSqbpAMckw7hI&hl=en&sa=X&ved=0ahUKEwizs4TTwrPJAhVDJQ8KHQ7bBLIQ6AEIIDAA#v=onepage&q&f=false) defines the difference between the two. Mike f 109.76.45.4 (talk) 18:11, 28 November 2015 (UTC)[reply]