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A magnetic fluid ring, which can be compared to a liquid O-ring, held at a given place by a magnetic field is used for various applications, such as seals, compressors, dampers, or sensors. The work of this type of system is the result of a number of factors, such as the distribution and magnitude of the magnetic field in the gap, rheological and magnetic properties, physical properties of the surrounding environment (interfacial phenomena) and operating conditions (differential pressure and relative velocity). The research area of this publication is related to the recognition and assessment of how the magnetic fluid properties influence the mechanism of the local loss of continuity for a single liquid ring. This applies to the case when the differential pressure on two sides of the magnetic fluid-free surface exceeds a critical value and a leak channel is formed. Previous studies have shown that the process of equalizing the pressure difference in this type of system is related to pressure jumps. This phenomenon has not been linked to such properties as saturation magnetization, dynamic viscosity or surface tension. This paper takes these factors into account. In addition, the shape of the stage (trapezoid and rectangle) on which the fluid is held and the magnetic field value are considered. The loss of continuity is an important issue and the obtained results allow this problem to be better understood and the magnetic fluid to be chosen for appropriate working conditions, e.g., in the case of multistage seals. The studied phenomenon may also contribute to the development of new types of pressure regulators or sensors. [ABSTRACT FROM AUTHOR]

One of the main engineering applications of ferrofluids is in magnetic fluid seals, working in rotary motion. An area, which has so far been insufficiently examined, is the mechanism of leaks between seal stages in this type of seal. This is an important issue in order to understand the principle of the seal operation and to properly design this type of seal. This paper presents the results of research into the mechanism of leaks between stages in multi-stage magnetic fluid seals. The tests were conducted when the pressure of the sealing air increased and reached its maximum value. The influence of the magnetic fluid properties, such as saturation magnetization or dynamic viscosity, was taken into account. Studies were performed for different seal temperatures. Experiments allowed models for determining the maximum pressure of the multi-stage seal to be proposed, based on the information about this pressure for a one-stage seal. This paper presents the comparative results of the critical pressure value obtained from experimental studies and calculations based on numerical simulations. [ABSTRACT FROM PUBLISHER]

Ferrofluids have various engineering applications, and one of them is magnetic fluid seals. Development for this design is a complex process, which requires knowledge about ferrofluid physical properties and magnetic field distribution inside the sealing gap. One of the most important parameters of ferromagnetic fluid seals is a critical pressure value. It is a pressure at which rapid leakage will occur. This publication presents the results of critical pressure value obtained from experimental studies and calculations based on numerical simulations. Shape of sealing stage, volume of ferrofluid, and volume of permanent magnet used in seal construction were taken into account. Experiments and calculations were performed for four ferrofluids differ in saturation magnetization, density, and zero magnetic field viscosity. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this publication is to determine the influence of selected factors on the durability and the tightness of ferrofluid seals working in water environments. Ferromagnetic fluid (FF) seals are one of the most common applications of magnetic fluid. New applications can be developed by extending the capabilities of these seals in fluid environments, especially in water. Design/methodology/approach – Tests were performed using ferrofluids with differing physical properties like density, dynamic viscosity and saturation magnetization. Working conditions, such as water pressure and peripheral speed, were taken into account. Findings – A mathematical description which allows the selection of an appropriate ferrofluid and the determination of the operating parameters of an FF seal was developed. Originality/value – This study concerns the influence of peripheral speed, water pressure and magnetic fluid properties on seal tightness. [ABSTRACT FROM AUTHOR]