22 containing a magnet 24 which can be of any shape is positioned upstream to close off the supply of fluid 16 by sealing the aperture 26 in the downstream magnet 28 which is a flat disc in this embodiment the ball 22 and the flat magnet 28 are encased inside a tubular cylinder 30 having a cap 32 the tubular cylinder 30 is made of mesh material consisting of stainless steel or a clear plastic composition the magnet 24 is preferably set immobilized inside the hollow ball 22 but can be freely mobile the hollow ball 22 can be brightly colored such as in pink or yellow this coloring would allow the attendant to readily determine whether the hollow ball 22 is floating or resting on the lower or downstream magnet 28 the hollow ball 22 seats on a thin apertured silicone liner 33 which enhances the effective sealing of the aperture 26 in the flat downstream magnet 28 when the level of the body fluid 16 falls proximate to the surface of the downstream magnet 28 and liner 33 turning to fig3 a second embodiment of the invention is disclosed wherein the floating in line ball valve system 34 comprises a cylinder 36 preferably made of a transparent plastic material e g teflon u2122 or a borosilicate glass which is substituted for the tubular mesh cylinder 30 of fig1 and 2.