The Force Decay leak test is used to test the seal integrity of a flexible or semi-rigid package that contains a headspace. It is well suited to test non-porous package material such as films, foils or laminates. The test package is placed in a vacuum chamber between two plates, one of which is connected to a force sensor. The chamber is evacuated at the start of the test and the flexible package will expand until the package reaches an equilibrium state with the internally applied pressure. Over a measured time, the force applied to the sensor will remain constant indicating a good seal or the force will decrease, indicating a leak in the package seal.
First, the test package is placed in chamber and the chamber is evacuated to a set pressure. Next, the flexible package expands putting pressure on the force sensor. A timed step checks for decay in the force being exerted on the force sensor. No decrease in the force on the sensor indicates good package integrity and is a pass rating. A measured decrease in force indicates a leak or test failure.