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Automatic self-cleaning ferromagnetic metal detector

  • US 4,100,491 A
  • Filed: 02/28/1977
  • Issued: 07/11/1978
  • Est. Priority Date: 02/28/1977
  • Status: Expired due to Term
First Claim
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1. A metal detector adapted for detecting ferromagnetic particles in a flowing fluid having low conductivity comprising:

  • probe means;

    mounting means adapted for attachment to container means for said fluid, said mounting means securing at least one end of said probe means in said flowing fluid;

    semipermanent magnetic pole means forming a part of said probe means with at least a portion of said semipermanent magnetic pole means being in contact with said flowing fluid;

    coil means adjacent said semipermanent magnetic pole means;

    voltage means;

    control means connected to said coil means, said control means selectively causing direct current flow from said voltage means through said coil means to magnetize said semipermanent magnetic pole means, said magnetization of said semipermanent magnetic pole means causing said ferromagnetic particles to collect on said portion in contact with said flowing fluid;

    said portion of said semipermanent magnetic pole means being constructed and arranged to have a gap therein, said gap being in contact with said flowing fluid;

    a conductivity sensor circuit including said voltage means connected to said semipermanent magnetic pole means and measuring current flow therethrough from said voltage means upon said collection of ferromagnetic particles bridging said gap to generate a warning signal when said current flow reaches a predetermined level;

    said warning signal being received by and activating said control means to supply alternating current from said voltage means to said coil means to demagnetize said semipermanent magnetic pole means thereby allowing said flowing fluid to carry away said collection of ferromagnetic particles.

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