I.Summary
This is HZ1731 full automatic surface tension tester including platinum plate method and
platinum ring method produced by . The surface tension is a basic property of liquid,
especially surfactant aqueous solution. Can measure the surface tension value of various
liquid quickly and accurately with physical method instead of chemical method. It has a
wide range of application. It can measure surface tension in hydropower sector to
strengthen supervision on the quality of insulating oil; it can measure and analyze the
surface tension value of various liquid in petroleum and chemical industry, scientific
research and education department.
1.1 What is the surface tension
Surface tension is the tension of liquid surface on any boundary line along the surface
due to the unbalanced molecular attraction. The resultant force on a molecule by
surrounding molecules inside the liquid is 0. However, that on the surface is not zero
because attraction on the molecule on the surface by gas phase molecular in the upper
space is smaller than that by the internal liquid phase molecule. The resultant force is
perpendicular to the liquid inside, resulting in automatic contracting trend in the surface of
the liquid and this contraction force is called surface tension.
Molecules inside the liquid are close to each other, maintaining a balanced distance
between molecules with attraction on a little farther distance and repulsion on a little
closer distance. It makes liquid molecules can only vibrate and rotate near the equilibrium
position unlike gas molecules that can diffuse infinitely. Liquid molecules near the surface
are only affected significantly by liquid inside. With uneven stress, the molecular in higher
velocity can easily escape from liquid and become steam thus resulting in molecule
