5.1 This method allows for the evaluation of seal quality by passing an ultrasound signal through the sealed area of a package or item. Poorly sealed areas will not transmit as much ultrasonic energy as properly sealed areas.

5.2 This method relies on quantitative analysis of ultrasound signal strength, providing a non-subjective approach to assessing package seal quality and detecting defects.

5.3 This technique has been used for inspecting a variety of materials including flexible pouch seals, rigid tray seals and other packaging components such as affixed valves. The precision and bias for any specific package and seal configuration needs to be individually determined and validated.

5.4 The C-Scan approach is useful for laboratory applications or off-line seal inspection. The L-Scan approach can be used for on-line, real time inspection of seal quality. The sensitivity of either approach to detect a given defect size and level of severity needs to be individually determined.

5.5 Sound waves propagate at different speeds through different materials generally moving faster through more dense materials. The acoustic impedance (expressed as g/cm²·μs) is the product of density (g/cm³) and velocity (cm/μs). Of particular importance is the extreme difference between the impedance of air and that of any solid material. Any gap or poorly bonded area can be readily detected.