One-sentence answer: Insulin pump reservoirs and infusion set tubing are part of a micro-dosing pathway, and any micro-leak directly causes dose deviation. With the CTS Sentinel I28 multi-function leak detector, differential pressure decay and mass flow testing can be run sequentially (in-series) in the same instrument to complete reservoir air tightness and infusion flow patency determination.
A micro-leak directly affects dosing accuracy, so stable criteria at small volumes are essential
The insulin therapeutic window is narrow, and deviations caused by sealing failure accumulate continuously, so outgoing inspection must be able to distinguish extremely small leaks.
Soft bladders deform noticeably when inflated, and stabilization time and support method directly affect readings.
The inner lumen of infusion set tubing is small, and when only pressure drop is measured, blockage and micro-leaks are easily confused with each other.
Sealing locations: the heat-sealed or welded surface between the reservoir bladder and the connector hub, the mating seal between the reservoir and the pump body, the connection between tubing and connector, and the bonded surface between tubing and needle hub.Consequences of leakage: actual infused dose is lower than the set value, affecting blood glucose control; air enters the fluid path and forms an air embolism; the sterile barrier fails; drug solution leaks and is wasted. Defects in a micro-dosing pathway often reveal their cost only after several hours of use.
Why multiple methods in series are essential here. Both risk categories in a micro-dosing pathway cause dose deviation: micro-leaks at the reservoir bladder, connector hub, or connector allow drug solution to seep out slowly, while blockage or kinking in the extremely fine infusion set tubing obstructs drug delivery. Both change the pressure trend inside the cavity, and when only pressure decay is used, the readings are highly similar, making it easy to misjudge tubing blockage as leakage, or to let a micro-leak be drowned out by the pressure drop caused by blockage. The criteria must therefore be separated: differential pressure decay compares the reference part with the part under test, cancels out ambient temperature fluctuation, and is used to distinguish micro-leaks; mass flow directly confirms tubing flow patency, and the two draw their own conclusions within the same sequence. Flexible bladders are also affected by volume effects and deform noticeably during inflation, so a contour-fitting support fixture must be used to limit deformation, and inflation rate and stabilization time must be fixed in the test program.
Differential pressure decay is preferred. The reference part and the part under test are pressurized and compared simultaneously, so ambient temperature effects cancel each other out in the differential pressure channel, making it easier to distinguish micro-leaks than single-channel direct pressure and better matching the judgment requirements of micro-dosing.
The inner lumen of the tubing is small, and blockage likewise causes pressure changes. Measuring pressure drop alone leads to misjudging a blocked tube as a leaking part, so within the same sequence the mass flow stage separately confirms flow patency, and the two conclusions do not interfere with each other.
Use a support fixture designed to the bladder contour to limit deformation, and fix the inflation rate and stabilization time in the test program; combined with temperature drift compensation, this improves test repeatability and reduces false rejection of conforming parts.
It matters; generally micro-leaks are judged first and flow patency second. If flow patency is tested first, the pressure change caused by tubing blockage interferes with the subsequent sealing reading, entangling the two conclusions. The I28 places the differential pressure decay micro-leak stage first and the mass flow patency stage second, so the two judgment conditions are independent and the results are clearer.
The key point for insulin pump reservoirs is to judge micro-leaks and tubing flow patency separately and accurately. The multiple methods in series of the CTS Sentinel I28, together with flexible-part support fixtures and a clean air supply, is suitable for volume outgoing inspection of micro-dosing consumables.
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