The pendant drop method of surface tension measurement: Equation interpolating the shape factor tables for several selected planes

For evaluation of the surface tension by the pendant drop method, the method of selected plane is often preferred to more precise and sophisticated treatments. The several selected planes method, which implies better verification of data, is used only seldom, which is likely due to low accessibility of data for other planes in a suitable form. This article presents equations which express the parameter 1/H with a maximum deviation of 10(-4), in terms of the shape parameter S-k for 5 planes with the distance from drop apex equal to 0.8-1.2 multiple of the equatorial diameter d(e). The aim of this paper is only to introduce this tool for easier use of the method; the analysis of advantages and disadvantages of using several planes was made prior by several authors.