Flangeless electromagnetic flowmeter

Claim 1

A flangeless electromagnetic flowmeter unit interposable between the end flanges of the upstream and downstream pipes of a line conducting a fluid whose flow rate is to be metered, the end flanges of the pipes having a predetermined diameter and a circle of bolt holes, said unit comprising: A. a cylindrical housing having a predetermined length and an external diameter which is uniform throughout its length and is smaller than that of the circle whereby when the unit is interposed between the end flanges of the pipes with the ends of the housing abutting these end flanges, the housing lies within the circle and the flanges are bridged by bolts passing through the holes to encage the unit and subject it to a compressive force effecting a fluid seal; B. a non-magnetic spool having substantially the same length coaxially supported within said housing and provided with end faces which abut the end flanges of the pipes to define with said housing an internal cavity, said spool forming a fluid conduit having a longitudinal flow axis which joins the upstream and downstream pipes, said spool having a strength sufficient to withstand the pressure of fluid flowing in the conduit; C. a pair of electromagnet coils disposed at diametrically-opposed sides of said spool to create a magnetic field whose lines of flux extend across the conduit, said coils lying on a coil axis which is normal to said flow axis; D. a pair of electrodes mounted on said spool at diametrically-opposed positions along an electrode axis perpendicular both to the coil axis and to the flow axis whereby the fluid which flows through the conduit intersects said lines of flux to induce a signal in said electrodes which is a function of flow rate; and E. a strap of ferromagnetic material joining the electromagnetic coils to define a magnetic circuit therewith.