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Flow control system for liquid chromatographs

  • US 4,137,011 A
  • Filed: 06/14/1977
  • Issued: 01/30/1979
  • Est. Priority Date: 06/14/1977
  • Status: Expired due to Term
First Claim
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1. In a liquid chromatograph system having a motor driven pump for supplying a carrier containing isocratic or gradient controlled elution solvents and for delivering the carrier to an LC column under pressure, a method of flow control of the pump output comprising the steps of measuring pump output pressure over at least one cycle of pump operation at constant pump motor speed to develop a pressure reference level for a given carrier;

  • subsequently varying the speed drive of the pump motor to maintain the output pressure equal to the pressure reference level;

    measuring the pattern of pump motor speed during a cycle of operation;

    storing said pattern in a memory to provide a pump motor speed reference, measuring the actual pump motor speed during operation of the system;

    comparing the pump motor speed reference and actual pump motor speed to obtain a difference signal in speed caused by changes in system variables;

    continually changing the pressure reference level applied to the pump in response to the difference signal.

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