METHOD FOR DETERMINING SURFACE TENSION COEFFICIENT OF LIQUID Russian patent published in 2020 - IPC G01N13/02 

FIELD: measurement technology.

SUBSTANCE: invention relates to the field of surface phenomena in liquid and can be used in measuring equipment for determination of surface tension coefficient of liquid. Method for determining surface tension coefficient of liquid σ consists in formation on a horizontal top edge of a capillary of a droplet of the analyzed liquid with a spherical surface due to the supply of excess gas pressure P_E into the vessel with the analyzed liquid and height measurement a of formed droplet of the analyzed liquid in order to determine the radius of curvature R of the spherical surface of the formed droplet of the analyzed liquid, excess gas pressure value P_E is controlled during feeding into vessel with analyzed liquid, and then measured at the moment of formation of a droplet of the analyzed liquid with a spherical surface on the horizontal upper edge of the capillary, corresponding to equilibrium state between measured value of gas excess pressure P_E and sum of spherical surface Laplace pressure P_L of formed drop of analyzed liquid and hydrostatic pressure P_H of the analyzed liquid column in the capillary, height a of analyzed liquid formed droplet is measured above capillary horizontal top edge, and surface tension coefficient σ of the droplet of the analyzed liquid are determined from the radius of curvature R of the spherical surface of the formed droplet of the analyzed liquid and the value of the Laplace pressure P_L spherical surface of formed droplet of analyzed liquid, equal to difference between excess controlled gas pressure P_E of gas and hydrostatic pressure P_H of the analyzed liquid column in the capillary by using the formula: σ=1/2k∙P_L∙R=((r²+a²)/4a)∙k(P_E-P_H), where k is coefficient, which is device constant, which is determined from measurement of value σ_r of reference liquid with known coefficient of surface tension; P_L is Laplace pressure, Pa; P_E – excess gas pressure supplied into the vessel with the analyzed liquid, Pa; P_H – hydrostatic pressure of the column of the analyzed liquid in the capillary, Pa; R is radius of curvature of spherical surface of formed droplet of liquid, m; a – height of formed droplet, m; r is external radius of capillary, m.

EFFECT: development of new method for determination of coefficient of surface tension of liquid.

1 cl, 2 dwg