Image Number 2 for United States Patent #4061031.
Combination of a flow meter and a bubble trap for blood which has been extracted for extra-corporeal treatment, in particular for dialysis. Said combination comprises a container divided by a vertical partition wall into a vertically elongated inlet chamber having an inlet opening receiving the blood flow to be measured and treated, and an outlet chamber of substantially greater cross-section than the inlet chamber and in liquid communication with an outlet opening. According to the invention, a narrow passage with a substantially smaller cross-section than the inlet opening is provided through the partition wall, preferably near the lower end of the same, causing the liquid level in the elongated inlet chamber to rise substantially above the level of said narrow passage. The difference between the liquid levels in the respective chambers will be an indication of the blood flow rate through the container, a pressure equalization opening being provided through the wall above said liquid levels. Both chambers are serving as efficient bubble traps, the influx of blood to the inlet chamber taking place below the liquid level and preferably in a vertical direction, and the output chamber providing the advantageous combination of an extended free surface and a reduced blood flow rate.