Lined flow tube for electromagnetic flowmeter

Claim 1

A magnetic flowmeter adpated to operate with high-temperature fluids and with highly corrosive fluids or with fluids containing abrasive matter, said flowmeter being provided with a pipe section surrounded by electromagnetic coils to establish a field therein whereby fluid passing through said section and subjected to the field has a voltage induced therein, said pipe section comprising: A. a tube formed of high-strength, non-magnetic metal; B. a liner disposed within said tube and constituted by a ceramic material which is strong under compression but relatively weak under tension, said material being selected from the class consisting of alumina, zirconia, aluminumsilicate and zirconium-silicate, said metal tube reinforcing said liner whereby said pipe section is capable of operating under rigorous conditions, C. mounting flanges secured to the ends of said metal tube for attaching said pipe section to complementary flanges on fluid inlet and outlet pipes, said liner protruding slightly at either end beyond said mounting flanges whereby said protrusions are pressable into gaskets interposed between said mounting flanges and said pipe flanges to effect a leak-proof seal, and D. a pair of electrodes passing through holes in said linear and mounted at diametrically opposed positions on said pipe section, each electrode being insulated from said tube and having a head disposed on said liner to make contact with fluid passing therethrough.