METHOD OF DEFINING FLUID SURFACE TENSION Russian patent published in 2011 - IPC G01N13/02 

FIELD: physics.

SUBSTANCE: proposed method comprises immersing vertical capillary bottom end into analysed fluid and measuring fluid capillary lift height. Note here that, additionally, measured is the difference in fluid lift height (h_m-h_n) for two or several vertical sections in flat slit capillary formed by two converging flat surfaces, capillary width being constant in vertical section. Note that horizontal section varies from 0 to d capillary length equal to x, with x>>d. Note also that fluid lift heights h_m and h_n correspond to capillary vertical sections with zero width at distances equal to x_m and x_n, respectively, while capillary width in these sections equals d_m and d_n, where m=1, 2, 3…, n=1, 2, 3… are numbers of relevant vertical sections (n≠m), while surface tension is determined by formula: where α is fluid surface tension, N/m; ρ is fluid density, kg/m³, g is free fall acceleration, m/s²; (h_m-h_n) is difference in lift height corresponding to capillary vertical sections distance from capillary zero-width section equal to x_m and x_n, m; d is calibrated capillary width corresponding to vertical section spaced from zero-width section by distance x, m.

EFFECT: higher accuracy, simplified procedure.

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