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US 4,825,168 AGranted
Remote conductivity sensor using square wave excitation
AssigneeCobe Laboratories, Inc.
InventorsFrancis T. Ogawa, George J. Eilers, Michael R. Manes, Donn D. Lobdell, Terry D. Boucher
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Abstract
A liquid conductivity sensor which features simply and inexpensively driving the excitation transformer of a two-transformer/fluid-loop remote conductivity sensor with a square wave excitation signal provided by a digital timer and a flip-flop. Also disclosed is using an electrodeless conductivity sensor to sense conductivity of dialysate.
Claims10
Apparatus for remotely sensing conductivity of a fluid passing through it, said apparatus comprising
- a cell including means for defining a fluid flow path having a fluid loop and excitation and sensing transformers each having a core encompassing a portion of said fluid loop, and
- a digital timer and a flip-flop connected to provide a square wave excitation signal to said excitation transformer.
Dialysate preparation and supply apparatus comprising
- a dialysate supply line,
- fluid flow path means for defining a fluid flow path in said supply line, said means having an inlet and an outlet and two fluid paths between the two, thereby defining a fluid loop,
- an excitation transformer comprising a first toroidal core having a hole through it and wire turns around it, said core encompassing a portion of said fluid flow path means and said fluid loop therein,
- a sensing transformer comprising a second toroidal core having a hole through it and wire turns around it, said core encompassing a portion of said fluid flow path means and said fluid loop therein, and
- a digital timer and a flip-flop connected to provide a square wave excitation signal to said excitation transformer.
2 more elements
Dialysate preparation and supply apparatus comprising
- a dialysate supply line,
- fluid flow path means for defining a fluid flow path in said supply line, said means having an inlet and an outlet and two fluid paths between the two, thereby defining a fluid loop.
- an excitation transformer comprising a first core having a hole through it and wire turns around it, said core encompassing a portion of said fluid flow path means and said fluid loop therein,
- a sensing transformer comprising a second core having a hole through it and wire turns around it, said core encompassing a portion of said fluid flow path means and said fluid loop therein, and
- a digital timer and a flip-flop connected to provide a square wave excitation signal to said excitation transformer.
2 more elements
Dependencies are inferred from the claim text.