The definition of the leakage rate is necessary to make requirements comparable. The term leakage refers to the unintentional escape of gases or liquids from enclosed vessels.
There is no absolute tightness. It is therefore necessary to define a permissible leakage rate in order to reduce the risk to people and the environment.
Leakage rate definition
The general unit of leakage rate (Q or QL) is mbar·l/s.
Example 1: If in a volume of 1 litre (l), the pressure drops by 1 mbar within 1 s, this corresponds to a leakage rate of 1 mbar·l/s.
Example 2: A volume of 1 litre=1000 cm3 contains of gas at a pressure of 1 bar. If gas leaks precisely 1 cm³ per second, the pressure drops 1 mbar per second. Consequently, the leak rate is 1 mbar*l/s.
Leakage rate unit conversation
| Unit | mbar·l/s | Pa·m3/s | Pa· l/s | std cm3/s | mol/s |
|---|---|---|---|---|---|
| 1 mbar·l/s | 1 | 1·10-1 | 1·102 | 9,87·10-1 | 2,27·104 |
| 1 Pa·m3/s | 1·101 | 1 | 1·103 | 9,87 | 4,40·10-4 |
| 1 Pa·l/s | 1·10-2 | 1·10-3 | 1 | 9,87·10-3 | 4,40·10-7 |
| 1 std cm3/s | 1,01 | 1,01·10-1 | 1,01·102 | 1 | 4,46·10-5 |
| 1 mol/s | 2,27·105 | 2,27·103 | 2,27·106 | 2,24·104 | 1 |
Other Leakage rate designations and equivalents e.g. valve seat tests
| Value 1 | Value 2 | Value 3 | Conversation API STD 598 |
|---|---|---|---|
| 1 ml = 0,001 L/s | 1 milli litre/s | 1000 mm3/s | 16 drops/s |
| 1 ml = 0,001 L/s | 1 milli litre/s | 1000 mm3/s | 100 bubbles/s |
Remark: Leakage rates in drops/s, bubbles/s and mm3/s contain in some standards such as ISO 5208 and API STD 598 for specified rate classes at for valve seat tests
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