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Medical fluid flow rate controlling device

  • US 4,375,813 A
  • Filed: 02/10/1981
  • Issued: 03/08/1983
  • Est. Priority Date: 02/10/1981
  • Status: Expired due to Fees
First Claim
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1. An apparatus for controlling the flow rate of an intravenously administered medical liquid to a patient from a supply of medical liquid, said apparatus comprising:

  • (a) a first chamber means for containing a portion of said liquid and a gas, having a liquid inlet, a liquid outlet, and a gas phase connection, said liquid inlet designed to receive liquid from the supply of medical fluid;

    (b) a second chamber means for containing a portion of said liquid and a gas, having a liquid inlet, a liquid outlet, and a gas phase connection, said first chamber means having means for moving said first chamber means vertically with respect to the second chamber;

    (c) gas phase pressure equalization means connected to the gas phase connections for equalizing the gas phase pressures in said first and second chambers;

    (d) first liquid connecting means fluidly connecting the liquid outlet of the first chamber to the liquid inlet of the second chamber, said first liquid connecting means having at least one flow restrictor in the fluid flow path through which a known quantity of liquid flows when a given differential pressure exists across it;

    (e) a third chamber means having a liquid outlet from which liquid passes to the patient and a liquid inlet for receiving liquid from the second chamber; and

    (f) second liquid connecting means fluidly connecting the liquid outlet of the second chamber to the liquid inlet of the third chamber, said second liquid connecting means having a membrane valve in the flow path which when wet passes liquid but not gas under normal operating conditions.

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