METHOD FOR DETERMINING THE SURFACE TENSION COEFFICIENT OF A LIQUID BY EXPRESS ANALYSIS Russian patent published in 2021 - IPC G01N13/02 

FIELD: surface phenomena.

SUBSTANCE: invention relates to the field of surface phenomena in a liquid and can be used in measuring technology to determine the surface tension coefficient of the test liquid. In order to determine the coefficient of surface tension of a liquid by the method of express analysis, a drop (14) of the same height is formed of the reference liquid (10) and a drop (15) close in chemical composition of the test liquid (11) is formed with spherical surfaces on the horizontal upper cut (13) of the capillaries (4) (Fig. 2). For this purpose, excess gas pressure Ρ_E is supplied to the vessel (1) with the reference liquid (10) and to the vessel (2) with the test liquid (11) through the side branches (5) using the microcompressor (6). The value of the excess gas pressure Ρ_E is monitored during the supply to the vessel (1) with the reference liquid (10) and to the vessel (2) with the test liquid (11) using fine adjustment valves with manometers (7). The excess controlled gas pressure Ρ_E affects the surface layer of the reference liquid (10) and the test liquid (11), forcing them to rise along vertically inserted capillaries (4) until the formation of drops (14) and (15) with spherical surfaces on the horizontal upper cut (13) of capillaries (4). At the moment of the formation of a drop (14) of the reference liquid (10) with a spherical surface at the horizontal upper cut (13) of the capillary (4), the excess gas pressure Ρ_Eref is measured with the help of a fine adjustment valve pressure gauge (7), the valve (7) is closed and the gas supply to the vessel (1) is stopped. Further, using the video monitoring tool (9) (Fig. 1) and the fine adjustment valve (8) with a pressure gauge, a drop (15) of the test liquid (11) with a spherical surface is formed on the horizontal upper cut (13) of the capillary with a height equal to the height of the formed drop (14) of the reference liquid (10) (Fig. 2) at the moment of formation of the drop (15) of the test liquid (11) with a spherical surface on the horizontal upper cut (13) of the capillary (4) the value of the excess gas pressure P_Etest is measured using a fine adjustment valve pressure gauge (8), the valve 8 is closed and the gas supply to the vessel (2) is stopped (Fig. 1). Knowing the values of the excess gas pressure Ρ_Eref and P_Etest in vessels (1) and (2), respectively, the difference in the values of the excess gas pressure ΔР_E in the vessels with the reference and the test liquids is determined. Using the difference in the values of the excess gas pressure ΔР_E in the vessels with the reference and the test liquids at the same heights of formed drops of the reference and test liquids above the horizontal upper cut of the capillary, the value of the surface tension coefficient of the drop of the test liquid is determined by the method of express analysis by comparing with the value of the surface tension coefficient of the drop of the reference liquid, applying the appropriate analytical dependence.

EFFECT: simplification of the procedure for performing a comparative analysis of the surface tension coefficient of the test liquid with the value of the surface tension coefficient similar in chemical composition to the reference liquid while reducing the time spent on performing express analysis while maintaining a high degree of accuracy of the results obtained.

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