Evaluation of the measurement signal from a vacuum leak detector

A method for evaluating the measuring signal of a vacuum leak detector comprising a vacuum pump and a test chamber connected with the vacuum pump and a gas detector connected with the test chamber,

• characterized by
• determining the system time constant τ of the vacuum leak detector, wherein the system time constant τ is the duration of the system-related rise of the measured signal in response to a gas component escaped through a leak in the test object or the duration of the system-related drop of the measured signal in response to a gas component no longer from a leak in the test object, followed by the steps of:
• generating a measuring signal I(t) of the gas drawn from the test chamber at a time t, using the gas detector,
• buffering the measured signal I(t),
• forming a measuring signal Í(t+t0) prognosed for a future time t+t0, based on the measured value of the buffered measuring signal I(t) and the system time constant τ, where t0<τ,
• generating a measuring signal I(t+t0) of the gas drawn from the test chamber at a time t+t0, using the gas detector,
• forming the difference between the measuring signal I(t+t0) and the prognosed measuring signal Í(t+t0),
• judging, whether the test object has a leakage, based on the difference formed.