A method for determining maximum size of a membrane by the bubble method is developed.

RF patent № 2248552

A method for determining maximum size of a membrane by the bubble method. The invention relates to test and experimental equipment. It can be used to check structural properties of thin porous films in chemical, medical, radio and electronic industries and other branches. The objective of the invention is improving the effectiveness of tests owing to prevention of membrane destruction and expansion of the range of membrane thickness that can be measured by the proposed method. The objective set is attained by placing the membrane, which was preliminarily impregnated with fluid, into a cell, then the cell is filled with a fluid, a gas is supplied to the cell and its pressure is measured. The cell with the membrane is placed into a vessel. The cell and the vessel are hydraulically connected. A nondestructive pressure differential is established on the membrane by pumping the fluid out of the vessel. The gas is supplied into the vessel. Vapours of the same fluid are used as the gas, the vapour pressure in the vessel is constantly measured. The pressure over the membrane, at which the pressure differential over it disappears, is fixed. Using the pressure, the surface tension coefficient is derived, then the maximum size of membrane pores is calculated using the Laplace formula.