Pressure and leakage

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With some formulas (Black frame) the appropriate on-line computation assistance can be opened by clicking on the formula window.

As this connection the cross section of the hole is regarded constant. If the test pressure will changed also the lost pressure will changed. The result of this is a changing of the leakage. This connection is again reflected by the following formula:

Calcultation from leakages by different pressures

The leakage changes thus squarely proportionally to the pressure.

The missing pressure or the missing leakage can be easily calculated by appropriate changing over. With the units it must be paid attention to the fact that the
same unit for the appropriate variables is always used (for example kPa for all pressures). With the pressures it always concerns absolute pressures (e.g. 100kPa over pressure = 200kPa absolute pressure).


Defaults :

Leakage QA = 10 cm3/min with test pressure PA = 100kPa (absolute 200kPa). What is the leakage with a test pressure of PB = 400kPa (absolute 500kPa) ?

The against-pressure (ambient pressure) is to be accepted for the sake of simplicity with PG = 100kPa:

QB = 10 * (5002 - 1002) / (2002 - 1002) = 80 cm3/min

By a simple increase in pressure it is possible to get a better recognizability for leakages. But have a look for the possibilities of the test volume (e.g. the pressure strength).