Process for manufacturing a measuring tube of an electromagnetic flow

Abstract

To introduce an insulation (3) of desired thickness into a measuring tube (1) of an electromagnetic flow sensor at low cost forming a tight joint, said measuring tube comprising a metal tube (2) having a respective metal flange (4, 5) at each end (21, 22),the respective metal flange (4, 5) at each end is slipped over the outside (23) of the metal tube in such a way that a front side (41, 51) of the metal flange projects beyond the end of the metal tube by an amount at least equal to the thickness of the insulation (3), and a rear side (45, 55) of the metal flange is permanently and tightly joined to the outside (23) of the metal tube. Before being slipped on, each metal flange is provided, from the front side, with a flute (42, 52) which forms a first annular groove (43, 53) at its inner end. A mandrel whose diameter is determined by the desired thickness of the insulation is introduced into the lumen of the metal tube. It has a filler inlet and two end flanges, one at each end, which cover the flutes of the respective metal flanges at the front side. The insulation is then filled in through the filler inlet in a liquid state and allowed to solidify.