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Apparatus and method for the indirect measurement and control of the flow rate of a liquid in a piping system

  • US 4,108,574 A
  • Filed: 01/21/1977
  • Issued: 08/22/1978
  • Est. Priority Date: 01/21/1977
  • Status: Expired due to Term
First Claim
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1. Apparatus for continuously controlling the rate of flow of a liquid in a piping system in agreement with a desired flow rate, the apparatus comprising:

  • (a) a centrifugal pump;

    (b) means for driving said pump, said driving means having a continuously variable speed capability;

    (c) means for indirectly and continuously measuring the instantaneous rate of flow of the liquid in the piping system, said indirect measuring means including(A) means for sensing at least two flow-related variables, said flow-related variables being associated with said pump and said driving means, said sensing means also including means for generating and transmitting signals representative of the instantaneous value of each of the sensed variables;

    (B) calculating means including(i) memory means containing stored therein a set of mathematical relationships relating flow rate to said two flow-related variables,(ii) converter means for receiving the transmitted signals and transforming the signals into a first converted signal representative of flow rate by use of the stored mathematical relationships, and(iii) means for comparing a reference signal representing the desired flow rate with said first converted signal and for determining the error therebetween; and

    (d) control means responsive to said error varying smoothly the speed of said variable speed drive means.

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