LEAK TESTING · ENGINEERING CALCULATOR
Compare viscous and molecular estimates for an idealised capillary, together with the Knudsen numbers at each end.
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Model
Calculate
Assumptions and use
The coefficients shown use diameter and length in centimetres and pressure in mbar; the calculator converts the entered units automatically and reports SI throughput. The flow regime can vary along the channel. Real defects may be short, rough, tortuous or partly blocked: these two estimates are not bounds on an actual defect.
Worked example
Default example: diameter 70 µm, length 8 mm, outside pressure 100000 Pa and inside pressure 0.01 Pa.
Record the units, gas, temperature, background and instrument settings with every result. Confirm the model assumptions before applying a calculated limit to a real test.
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