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System and method for monitoring operation of a pump

  • US 7,878,765 B2
  • Filed: 02/28/2006
  • Issued: 02/01/2011
  • Est. Priority Date: 12/02/2005
  • Status: Active Grant
First Claim
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1. A method for controlling fluid pressure in a multiple stage pump comprising:

  • accessing a baseline pressure profile for a known good dispense cycle;

    operating a feed pump, a dispense pump and a set of valves to perform a new dispense cycle including a fill segment and a dispense segment;

    continually taking pressure measurements during the dispense cycle of fluid in a dispense chamber using a pressure sensor disposed to measure pressure in the dispense chamber;

    creating a first operating profile from the pressure measurements taken during the new dispense cycle;

    during one or more of the fill segment or the dispense segment of the new dispense cycle, comparing each of one or more values associated with the first operating profile with a corresponding value associated with the baseline profile to determine if each of the one or more values associated with the first operating profile is within a tolerance of the corresponding value associated with the baseline profile; and

    during one or more of the fill segment or the dispense segment, if the one or more values associated with the first operating profile is not within tolerances, generating an alarm;

    wherein operating the feed pump, dispense pump and set of valves to perform the fill segment comprises;

    operating the feed pump to reduce a volume of a feed chamber at a first predetermined rate;

    opening a barrier valve to allow a fluid in the feed chamber to enter said dispense chamber while keeping an outlet valve closed so that none of the fluid entering the dispense chamber is dispensed;

    taking pressure measurements of the fluid in the dispense chamber using the pressure sensor;

    determining whether a first pressure measurement is greater than a predetermined pressure;

    in response to the first pressure measurement being greater than said predetermined pressure, operating said dispense pump to increase a volume of the dispense chamber at a second predetermined rate;

    taking a second pressure measurement while the dispense pump is operating to increase the volume of the dispense chamber;

    determining whether the second pressure measurement is greater than a first threshold or less than a second threshold;

    in response to determining that the second pressure measurement is greater than the first pressure threshold, operating the feed pump at a decreased speed;

    in response to determining that the second pressure measurement is less than the second threshold, operating the feed pump at an increased speed;

    determining whether the operation of the dispense pump has caused the volume of the dispense chamber to reach a predetermined volume;

    in response to determining that the volume of the dispense chamber has not reached the predetermined volume, repeating the method from the step of measuring the second pressure; and

    in response to determining that the volume of the dispense chamber has reached the predetermined volume, stopping the operation of the feed pump and the dispense pump.

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