Pressure can fall in a sealed test circuit
A pressure decay test fills the pack and the connected fixture with gas, isolates the circuit and measures the pressure over time. Rapid filling can leave the gas warmer than the surrounding pack and fixture. At approximately fixed volume and with the same amount of gas in the circuit, absolute pressure falls as the gas cools. A downward trace can therefore appear even when no gas escapes.
Establish the thermal baseline
Run a verified intact pack of comparable geometry and condition through the same fill and hold sequence. A pressure fall that is strongest just after filling and changes with the starting temperature or stabilization time points to a thermal contribution. Record the fill pressure, starting temperature and the interval over which you evaluate the trace.
A real leak can occur while the gas is cooling. Establish a stable baseline and check a reference leak before interpreting a small decay signal. For flexible packs, changes in volume and fixture seating can also affect pressure.
Packaging sample showroom of SamBound New Material Technology Company Ltd. (sambound.com).
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SamBound New Material Technology Company Ltd.
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