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Liquid level monitoring

  • US 4,890,490 A
  • Filed: 06/13/1988
  • Issued: 01/02/1990
  • Est. Priority Date: 07/06/1987
  • Status: Expired due to Fees
First Claim
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1. A method of monitoring liquid level within a containment vessel, comprising transmitting acoustic wave pulses from transducer means along a waveguide which extends beneath the upper surface of the body of contained liquid and which has at least one pulse-reflecting discontinuity for exposure to the liquid, and analysing the reflected pulse or pulses to detect any loss of acoustic energy as a result of immersion of said discontinuity or discontinuities in the liquid, said method being characterised in that the acoustic wave energy is in the form of Lamb waves injected into the waveguide, said transducer means is located wholly external to the vessel interior, and the waveguide passes through a sealed penetration in a wall of the vessel said analysing comprising using progressive reduction of the amplitude of the reflected pulse and selecting a mode of said waves having an energy distribution having less energy at the surface of the waveguide than at the center of the waveguide.

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