The invention relates to a test-leakage device comprising a tracer gas reservoir (12) and a tracer gas outlet (16), which is sealed by a membrane (30) consisting of silicon oxide. A heating device for heating the silicon oxide disc (32) is also provided. The permeability of silicon oxide to low-molecular gases is essentially dependent on its temperature, so that the leak rate of the test-leakage device can be modified and controlled by heating the silicon oxide membrane.
