by providing a dynamic magnetic seal of ferrofluid about the shaft using a non rotating magnetic system formed of a unitary pole piece with magnets contained in radial slots formed in an inner diameter of the pole piece opposite the shaft application_number US 18543298 A description while this invention has been particularly shown and described with references to preferred embodiments thereof it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims note since the device is radially symmetrical only the top half is shown in some of the drawings for simplicity referring now to fig4 and 5 of the drawings a preferred embodiment of the invention is shown in which the entire set of pole rings and bypass seals is machined as a single piece for example a single piece 40 of ferromagnetic stainless steel e g 17 4 ph alloy or 400 series stainless steel alloy is machined into a ring with an o ring sealing groove 42 formed on the od and magnetic pole tips 60 on the id the pole tips 60 at the id of the unitary pole ring 40 are machined as a series of small v grooves 63 in the id of the single machined part 40 the single machined part 40 is first made.