Three-toroid electrodeless conductivity cell

Apparatus for measuring the electrical conductivity of a fluid, comprising:

• a sandwich of first, second, and third toroids, each having a centrally located aperture surrounding an axis, the toroids being stacked together coaxially to form a bore permitting fluid passage therein;
• a magnetically transparent housing enclosing said toroids;
• a source of electrical current;
• mean for inducing a magnetic flux in the fluid passage by application of said electrical current to at least one of said toroids;
• means for sensing the magnetic flux coupled to at least one of said toroids;
• and
• switch means for selectively connecting each of said first, second, and third toroids as the magnetic flux including means in the fluid passage, and alternatively as the magnetic flux sensing means.

In combination, apparatus for measuring the electrical conductivity of a fluid, comprising:

• a sandwich of first, second, and third toroids, each having a centrally located aperture surrounding an axis, the toroids being stacked together coaxially to form a bore permitting fluid passage therein;
• a magnetically transparent housing enclosing said toroids;
• a source of electrical current;
• means for inducing a magnetic flux in the fluid passage by application of said electrical current to at least one of said toroids;
• means for sensing the magnetic flux coupled to at least one of said toroids;
• and
• means for measurement validation comprising means for selectively connecting and disconnecting each of said first, second, and third toroids as the magnetic flux inducing means in the fluid passage, and alternatively as to magnetic flux sensing means.

In combination, apparatus for measuring the electrical conductivity of a fluid, comprising:

• a sandwich of first, second, and third toroids, each having a centrally located aperture surrounding an axis, the toroids being stacked together coaxially to form a bore permitting fluid passage therein;
• a magnetically transparent housing enclosing said toroids;
• a source of electrical current;
• means for inducing a magnetic flux in the fluid passage by application of said electrical current to at least one of said toroids;
• means for sensing the magnetic flux coupled to at least one of said toroids;
• and
• means for measurement range selection comprising means for selectively connecting and disconnecting each of said first, second, and third toroids as the magnetic flux inducing means in the fluid passage, and alternatively as the magnetic flux sensing means.

A method of measurement validation with a fluid conductivity meter including a sandwich of at lest three toroids stacked together coaxially to form a bore permitting fluid passage therein, and a source of electrical current, comprising:

• inducing a magnetic flux in the fluid passage by application of said electrical current to a first one of said toroids;
• sensing the magnetic flux coupled to a second one of said toroids;
• selectively connecting the third toroids as the magnetic flux inducing means in the fluid passage;
• an
• comparing the sensed magnetic flux before and after connecting the third toroid.

A method of measurement validation with a fluid conductivity meter including a sandwich of at least three toroids stacked together coaxially to form a bore permitting fluid passage therein, and a source of electrical current, comprising:

• inducing a magnetic flux in the fluid passage by application of said electrical current to a first one of said toroids;
• sensing the magnetic flux coupled to a second one of said toroids;
• selectively connecting the third toroid as the magnetic flux sensing means;
• and
• comparing the sensed magnetic flux before and after connecting the third toroid.

A method of measurement range switching in a fluid conductivity meter including a sandwich of at least three toroids stacked together coaxially to form a bore permitting fluid passage therein, and a source of electrical current, comprising:

• inducing a magnetic flux in the fluid passage by application of said electrical current to a first one of said toroids;
• sensing the magnetic flux coupled to a second one of said toroids;
• selectively connecting the third toroid as the magnetic flux inducing means in the fluid passage;
• and
• measuring the sensed magnetic flux.

The method of measurement range switching in a fluid conductivity meter including a sandwich of at least three toroids stacked together coaxially to form a bore permitting fluid passage therein, and a source of electrical current, comprising:

• inducing a magnetic flux in the fluid passage by application of said electrical current to a first one of said toroids;
• sensing the magnetic flux coupled to a second one of said toroids;
• selectively connecting the third toroid as the magnetic flux sensing means;
• and
• measuring the sensed magnetic flux.