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Measurement of liquid level

  • US 5,249,463 A
  • Filed: 09/21/1992
  • Issued: 10/05/1993
  • Est. Priority Date: 09/26/1991
  • Status: Expired due to Term
First Claim
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1. A liquid level measurement device having upper and lower ends and comprising inner and outer probe conductors separated by a dielectric gap which is filled by a liquid up to a level to be measured and above that level by a gas or vapor, a coaxial feeder for applying R.F. pulses to the upper end of said probe for reflection at the surface of said liquid, said probe having a first discontinuity near its upper end for producing a first reference reflected pulse in response to each R.F. pulse and a second discontinuity below said first discontinuity but in said gas or vapor and above the normal maximum level of said liquid for producing a second reference reflected pulse in response to each R.F. pulse, and circuitry coupled to said probe for determining from the time differences between the reference reflected pulses and the pulse reflected from the surface of said liquid the distance between the surface of said liquid and said first discontinuity.

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