LEAK TESTING · ENGINEERING CALCULATOR
Calculate long-tube molecular-flow conductance, effective pumping speed, response and decay after a finite helium application.
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Model
Calculate
Assumptions and use
The straight-tube approximation requires L/D ≥ 10 and molecular flow. Fittings, elbows, valves and transitional flow need an appropriate separate model. Assume a mixed volume, constant speed and no additional adsorption memory. Verify real helium recovery on the assembled system.
Worked example
The example uses a 50 mm diameter, 5 m line, helium at 293.15 K, a 0.1 m³ volume and a 100 L/s pump.
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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