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Hydraulic safety circuit for a hemodialysis apparatus

  • US 5,624,551 A
  • Filed: 04/26/1994
  • Issued: 04/29/1997
  • Est. Priority Date: 04/28/1993
  • Status: Expired due to Term
First Claim
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1. In a hemodialysis apparatus having a conduit system including a first connector that is to be connected to a source of dialysis fluid, a second connector that is to be simultaneously connected to a source of flushing fluid, and a pressurizing pump selected from the group consisting of a membrane pump and a dialysis fluid degassing pump arranged in the conduit system,an improved hydraulic safety circuit arranged in the conduit system between the first connector and the second connector to avoid mixing of the dialysis fluid and the flushing fluid, said safety circuit comprising a first shut-off device arranged in the conduit system between the first connector and the second connector and having a buffer-side port arranged toward the first connector and an apparatus-side port arranged away from the first connector, a second shut-off device connected between the first connector and said buffer-side port of said first shut-off device, a sealable buffer volume that is formed between said first and second shut-off devices and that is sealed when said first and second shut-off devices are closed, the pressurizing pump being connected to said buffer volume for pressurizing said buffer volume to a defined pressure, a pressure sensor connected to said buffer volume, and an evaluating unit connected to a signal output of said pressure sensor to evaluate any deviation from said defined pressure in said buffer volume to detect any leakage through at least one of said first and second shut-off devices when said first and second shut-off devices are closed.

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