Matching or not matching flow rates in two flow paths

摘要

A flow rate of unconnected first and second fluid flows is matched or not matched, such as, but not limited to, matching or not matching the flow rate of the replacement water stream with the waste water stream in kidney dialysis. First and second flow paths are interconnected so substantially the same flow from a first positive displacement pump in the first path encounters a flow-rate transducer in the second path. A first set of transducer readings are taken for various values of the controllable first pump speed of the first pump. The first and second flow paths are disconnected, and a second set of transducer readings are taken for various values of the controllable second pump speed of the second pump. The flow rates are substantially matched or not matching by controlling one of the first and second pump speeds using the other of the pump speeds and the first and second sets of readings.