The Strange–Rahman–Smith equation is used in the cryoporometry method of measuring porosity. NMR cryoporometry is a recent technique for measuring total porosity and pore size distributions. NMRC is based on two equations: the Gibbs–Thomson equation, which maps the melting point depression to pore size, and the Strange–Rahman–Smith equation, which maps the melted signal amplitude at a particular temperature to pore volume.
Equation If the pores of the porous material are filled with a liquid, then the incremental volume of the pores Δ v {\displaystyle \Delta v} with pore diameter between x {\displaystyle x} and x + Δ x {\displaystyle x+\Delta \,x} may be obtained from the increase in melted liquid volume for an increase of temperature between T {\displaystyle T} and T + Δ T {\displaystyle T+\Delta T} by:
d v d x = d v d T k G T x 2 {\displaystyle {\frac {dv}{dx}}={\frac {dv}{d\,T}}{\frac {k_{GT}}{x^{2}}}}
Where: k G T {\displaystyle k_{GT}} is the Gibbs–Thomson coefficient for the liquid in the pores.
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