Leak rate converter
Convert leak rate between the vacuum and the pressure-testing units, and see how long a vessel would take to empty.
That's about the same as an ordinary vacuum system. A one-liter vessel at one bar would take about 1×10⁹ seconds to empty.
What it means
How big is that leak?
Leak rates are quoted for helium at room temperature. Air leaks about 2.7 times more slowly through the same hole, because its molecules are heavier.
Every unit
Your leak rate in every unit
Learn
Three things worth knowing
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1 atm·cc/s ≈ 1 mbar·L/s
They differ by 1.3%, which is why the two communities can compare notes without converting. A standard cc a second is 60 sccm.
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Why pressure times volume
By the gas law, pressure times volume is proportional to the number of molecules. Measuring a leak this way counts molecules, whatever pressure they happen to be at.
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Bubbles only find big leaks
A soapy-water test finds down to about 10⁻⁴ mbar·L/s. A vacuum system needs to be a hundred thousand times tighter than the tightest leak you can see.
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Background
About leak rates
A leak is a flow of gas, and gas flow is measured as pressure times volume per second — which is really a count of molecules. A car tire leaking 10⁻² mbar·L/s goes flat in about two months; a vacuum chamber needs 10⁻⁹ or better.
The human eye can see a bubble at about 10⁻⁴; below that the test has to be done with helium and a mass spectrometer.