Quantitative and visualization study on pressure resistance of magnetic fluid seals

Abstract The pressure resistance of magnetic fluid seals is a key performance indicator that ensures stable operation. Based on the data from actual sealing devices, current theories are difficult to verify and have yet to reach a consensus on the factors influencing pressure resistance. In order to quantitatively measure the pressure resistance of magnetic fluid seals, a homemade visual experimental system was used, employing transparent capillary tubes to simulate actual sealing gap geometry and synchronous imaging to observe magnetic fluid’s deformation process. The influence of the following factors on the pressure resistance of the differential pressure seals was quantitatively investigated: the magnetic induction intensity (the peak value B max regarded as the reference), difference of magnetic induction intensity ( Δ B ), capillary diameter, mass fraction of magnetic particles, and carrier fluid type. The tested B max range from 90 to 790 mT, with magnetic fluid mass fractions of 8% and 33%, and capillary inner radii of 0.07 mm and 0.14 mm. Within this measurement range, it is found that: 1. The pressure resistance of magnetic fluids is not only determined by Δ B but also by B max . 2. Magnetic fluids with higher concentration exhibit a higher saturation magnetization; therefore, the higher the concentration of the magnetic fluid, the stronger its pressure resistance. 3. The pressure resistance of magnetic fluids in small gaps is greater than that in large gaps. Both water-based and kerosene-based magnetic fluids used in this study adhere to the above laws and exhibit significant discrepancies between theoretical and actual values. Moreover, the deviation observed in kerosene-based magnetic fluids is smaller than that in water-based ones. In engineering applications, these factors must be comprehensively considered to develop a pressure resistance theory that better aligns with practical realities.