A leak-test approach that monitors the force generated by a flexible package under a controlled pressure difference.
Also called: force decay leak test; force decay.
Does force decay measure seal strength?
In a vacuum-based force-decay arrangement, a flexible package expands against a restraint and its reaction force is monitored over time. A peel test instead measures the force needed to separate a prepared seal specimen.
A leak can change the pressure difference driving package expansion and hence the measured force. Material flexibility and restraint belong to the measurement arrangement. A force-decay result should not be relabeled as a peel-strength value or treated as a substitute for a separate seal-strength question.
A very small internal gas volume can be depleted before a useful airflow-based signal is obtained. Monitoring package expansion can provide another signal in a suitable arrangement. Restraining plates and contact geometry form part of that measurement, rather than interchangeable accessories.
For a multi-pocket blister, specify which cavities the measurement resolves and how they are positioned. Some systems combine vacuum and force measurements; the installed architecture determines what signals are available.