Remote conductivity sensor having transformer coupling in fluid flow path

Claim 1

A cell for remotely sensing conductivity of a fluid passing through it, said cell comprising fluid flow path means for defining a fluid flow path in a supply line, said means having an inlet and an outlet and two fluid paths between said inlet and outlet, thereby defining a fluid loop, an excitation transformer comprising a first toroidal core having a hole through it and wire turns around it, said core encompassing a portion of said fluid flow path means and said fluid loop therein, and a sensing transformer comprising a second torodial core having a hole through it and wire turns around it, said core encompassing a portion of said fluid flow path means and said fluid loop therein, said second toroidal core having a first plane of symmetry that is perpendicular to the axis of its hole, said first plane of symmetry being coplanar with a plane of symmetry of said first toroidal core that is perpendicular to the axis of its hole, to thereby reduce leakage coupling between said transformers, said fluid flow path means comprising two circular conduit portions having a first length, centers, and ends and two connecting portions connecting the ends of different said circular conduit portions of a second length measured between the centers of said two circular conduit portions, the outer diameter of each said conduit portion being approximately equal to the inner diameter of a said core and said wire turns on it, said first length being approximately equal to the thickness of a said core and said wire turns on it, said second length being approximately equal to the outer diameter of a said core and said wire turns on it.