Magnetic fluid method for sealing liquid media

Abstract

Magnetic fluid seals for sealing gas environments are widely used in various industries due to their undeniable advantages. However, such seals are not capable of reliable sealing of liquid media with different polarities. The paper analyses physicochemical processes that lead to destructing magnetic fluid in a seal under the influence of a liquid medium in contact with it. There are results of experimental studies on sealing using magnetic seals of non-magnetic fluids with different polarity. The authors studied the tightness of a magnetic fluid seal capacity in contact with weakly polar liquids: MVP instrument oil, vaseline oil, and water as a highly polar liquid. For sealing water, the authors chose magnetic fluids with liquid siloxanes as the basis; they are immiscible with water and hydrophobic. Weakly polar liquids were sealed using magnetic fluid with a dispersion medium of triethanolamine, which is almost insoluble in hydrocarbon liquids and has a high dielectric permittivity and surface tension comparable in magnitude. It is established that magnetic fluid based on triethanolamine reliably seals the experimental bearing from penetrating of weakly polar liquids at an overpressure of 10 kPa and below. To seal polar liquid media, it seems promising to use oleophobic magnetic fluids based on PES-5, containing a large amount of filler in the form of ferrite particles. A magnetic fluid should have the smallest possible contact area with the sealed fluid and maintain a laminar flow regime.