Method and apparatus for precisely dispensing liquids

• US 6,453,927 B1
• Filed: 05/16/2001
• Issued: 09/24/2002
• Est. Priority Date: 05/16/2001
• Status: Expired due to Fees

• Current Assignee: International Paper Company
• Original Assignee: International Paper Company
• Inventors: Mara, F. John, Peterson, Jason W.
• Primary Examiner(s): Hepperle, Stephen M.
• Application Number:
  US09/858,734
• Time in Patent Office: 496 Days
• Field of Search: 417/5, 417/211.5, 417/287, 417/474, 137/565.33, 137/3, 137/93
• US Class Current: 137/3
• CPC Class Codes: G05D 11/132 by controlling the flow of the individual components G05D11/133 takes precedence
• CPC Class Codes: G05D 7/0682 using a plurality of flow sources
• CPC Class Codes: Y10T 137/0329 Mixing of plural fluids of diverse characteristics or conditions
• CPC Class Codes: Y10T 137/2509 By optical or chemical property
• CPC Class Codes: Y10T 137/86163 Parallel

Abstract

A method and apparatus are provided for continuously dispensing precise quantities of a liquid from a dispenser holding tank into a receiving tank. A first elastic tube permits fluid flow between the holding tank and the receiving tank and a first peristaltic pump controls the flow rate of liquid through the first elastic tube. A second elastic tube permits fluid flow between the holding tank and the receiving tank and a second peristaltic pump controls the flow rate of liquid through the second elastic tube. The flow rates through the first and second elastic tubes are independently controlled. The flow rate through the first elastic tube is maintained generally constant and at a substantially greater rate than the flow rate of the second elastic tube. The flow rate in the second elastic tube is varied to maintain a desired total flow rate into the receiving tank.

Claims

1. A method of continuously dispensing precise quantities of a liquid from a dispenser comprising a holding tank containing said liquid, a first elastic tube permitting fluid flow from a holding tank to a receiving tank, a second elastic tube permitting fluid flow between said holding tank and said receiving tank, a first peristaltic pump controlling the flow rate of said liquid through said first elastic tube, and a second peristaltic pump controlling the flow rate of said liquid through said second elastic tube, said method comprising the steps of independently controlling the flow rates of said liquid through said first elastic tube and said second elastic tube, maintaining a generally constant flow rate of liquid through said first elastic tube at a substantially greater rate than the flow rate of liquid through said second elastic tube, and varying the flow rate through said second elastic tube to maintain a desired total flow rate.

2. A method in accordance with claim 1 and including the steps of establishing a maximum flow rate of liquid through said second elastic tube, establishing a minimum flow rate of liquid through said second elastic tube and re-setting the flow rate of liquid through said first elastic tube and said second elastic tube when said flow rate through said second elastic tube equals either said minimum flow rate or said maximum flow rate.

3. A method in accordance with claim 1 and including the steps of continuously monitoring the concentration of liquid dispensed into said receiving tank and independently controlling the flow rates induced by said first peristaltic pump and said second peristaltic pump to maintain a constant concentration of liquid in said receiving tank.

4. A method in accordance with claim 1 and including the step of controlling the flow rate of a diluent from a diluent source through an elastic diluent tube to said holding tank with a diluent peristaltic pump and controlling the flow rate of a concentrate from a concentrate source through an elastic concentrate tube to said holding tank with a concentrate peristaltic pump.

5. A method in accordance with claim 4 and further including the steps of continuously monitoring the volume of solution in said dilution tank, activating said diluent peristaltic pump and said concentrate peristaltic pump when said volume of solution falls below a predetermined minimum volume and de-activating said diluent peristaltic pump and said concentrate peristaltic pump when said volume of solution exceeds a predetermined maximum volume.

6. A system for continuously dispensing precise quantities of a liquid into a receiving tank comprising a holding tank containing said liquid, a first elastic tube providing flow communication between said holding tank and said receiving tank, a second elastic tube providing flow communication between said holding tank and said receiving tank, a first peristaltic pump operatively engaged with said first elastic tube to control the flow rate of said liquid through said first elastic tube, a second peristaltic pump operatively engaged with said second elastic tube to control the flow rate of said liquid through said second elastic tube, and a controller connected to said first peristaltic pump and said second peristaltic pump, said controller maintaining a generally constant flow rate of liquid through said first elastic tube at a substantially greater rate than the flow rate of liquid through said second elastic tube and varying the flow rate through said second elastic tube to maintain a desired total flow rate.

7. A system in accordance with claim 6 and further comprising a concentrate source, a diluent source, an elastic concentrate tube providing flow communication between said concentrate source and said holding tank, an elastic diluent tube providing flow communication between said diluent source and said holding tank, a concentrate peristaltic pump operatively engaged with said concentrate tube, a diluent peristaltic pump operatively engaged with said diluent tube, and a sensor monitoring the volume of liquid within said holding tank said controller being connected to said sensor, said concentrate peristaltic pump and said diluent peristaltic pump.