Blood Dialysis Flowmeter Calibration via Bypass Loop
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Solution Overview
Problem
The existing calibration methods for flowmeters in blood dialysis systems require a reference flowmeter, which increases costs and system size, and struggle to achieve accurate calibration without directly affecting dialysis therapy.
Innovation Solution
A calibration method that uses a known volume of liquid to match the measurements of the inflow and outflow flowmeters, preventing liquid outflow to the blood channel and employing a bypass route to avoid pump-induced fluctuations, allowing for accurate calibration without a direct reference flowmeter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reference flowmeter is used for calibration, then measurement accuracy is improved, but system cost and size increase
Solution Approach 1:
The system performs self-calibration by comparing measurements between the inflow flowmeter and outflow flowmeter during a bypass operation where a known volume of liquid is circulated. The calibration is achieved through the system's own components without requiring an external reference flowmeter, thereby reducing system complexity while maintaining measurement accuracy
Solution Approach 2:
A bypass route is introduced as an intermediary pathway that allows a known volume of liquid to be circulated between the inflow and outflow flowmeters without affecting the actual dialysis therapy. This intermediary system enables calibration while keeping the main dialysis system operational and unchanged
2Duration of action of stationary object
If calibration is performed during normal operation, then therapy continuity is maintained, but measurement accuracy may be compromised
Solution Approach 1:
The calibration process is segmented into a separate bypass operation that is independent from the main dialysis therapy flow. The bypass route allows calibration to be performed in parallel without interfering with the primary treatment function, ensuring both continuity and accuracy
Solution Approach 2:
The system performs preliminary calibration actions during the bypass operation before returning to normal dialysis operation. This preliminary calibration ensures accurate measurements are established beforehand, maintaining both therapy continuity and measurement precision
Data Source
AI summary
Provided is a calibration method for flowmeters in a blood dialysis system, whereby highly accurate calibration can be performed even by omitting a reference flowmeter not directly relating to dialysis therapy. This calibration method comprises: while preventing outflow into a blood channel in a blood purifier, supplying a liquid to a channel, said channel passing through an inflow flowmeter and an outflow flowmeter; and then calibrating the inflow flowmeter and the outflow flowmeter correction whereby, at the time of liquid supply, a value measured by the outflow flowmeter is equalized to a value measured by inflow flowmeter.