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RF Admittance apparatus and method for monitoring the contents of a pipe

  • US 4,568,874 A
  • Filed: 02/17/1983
  • Issued: 02/04/1986
  • Est. Priority Date: 02/17/1983
  • Status: Expired due to Term
First Claim
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1. A probe responsive to the degree to which the pipe is filled with a dielectric or conductive material and adapted for mounting between a pair of sections of the pipe and passing said material therethrough between said pair of pipe sections comprising:

  • tubular conductive probe measuring electrode means having a hollow interior adapted for forming part of a material passageway through said probe between said pipe sections;

    a first pair of tubular solid insulation means each axially displaced from said probe measuring electrode means on either side of said probe measuring electrode means for electrically insulating said either side of the probe measuring electrode means and having a hollow interior adapted for forming part of the material passageway through the probe between said pipe sections;

    a pair of tubular conductive guard electrode means each outwardly axially displaced from said probe measuring electrode means on either side of said probe measuring electrode means separated from said probe measuring electrode means by one of said pair of first solid insulation means and having a hollow interior adapted for exposure to said material of said pipe and for forming part of said material passageway through said probe;

    a pair of tubular conductive ground electrode means adapted for grounding and each outwardly axially displaced from said probe measuring electrode means on either side of said probe measuring electrode means between one of said pair of guard electrode means and a section of pipe proximal the one guard electrode means;

    a second pair of tubular solid insulation means each outwardly axially displaced from said probe measuring electrode means on either side of said probe measuring electrode means between one of said pair of guard electrode means and a section of pipe proximal the one guard electrode means and within one of said pair of ground electrode means and adapted for electrically insulating said pair of ground electrode means from said pair of guard electrode means and said material and further having a hollow interior adapted for forming part of said material passageway.first conductor means having a first end coupled to said probe measuring electrode means and a second end adapted for supplying an AC measuring potential to said probe measuring electrode means;

    second conductor means having a first end coupled to at least one of said pair of guard electrode means and a second end adapted for suppying a separate AC guard potential to said guard electrode means; and

    capacitance means in series with said first conductor means, said probe measuring electrode means and said material in said probe and having an admittance which is large compared to the admittance of the probe measuring electrode means expected when said probe is filled with an insulating material of relatively low dielectric constant, and small when compared to said admittance expected when said probe is filled with conductive material of high conductivity.

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