Choosing the Observation Window for a Pressure Decay Leak Test

A slow leak needs time to build a measurable signal

If pressure difference, temperature and volume stay reasonably stable, a slow gas leak can produce a larger measured pressure drop over a longer interval. In an empty-pack test, include the connected fixture volume when assessing the expected pressure response. A larger volume can yield less pressure drop over the same interval for a comparable flow.

Compare longer windows with reference runs

Repeat intact-pack runs and a relevant reference leak at candidate durations. Compare how well the signals separate. Temperature drift, fixture motion or sensor offset can make the reference traces drift as well. A longer interval can also change the pressure difference enough that a constant-flow approximation no longer applies.

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Choose an observation interval that separates the challenge from the intact baseline with repeatable results under the expected test conditions. Record stabilization and observation as separate parts of the cycle.

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