Influences on Burst Values
The burst value of a pouch of a given seal strength (e.g. 1 lb/inch) is dependent upon an number of factors including:
- The dimensions of the pouch – the size of the pouch as well as the width to length ratio directly impact the bust value. In general, the larger the pouch, the lower the value;
- The configuration of the pouch – e.g. the same size chevron, three-side seal, and header bag will yield different burst values;
- The materials of construction – nonporous pouches will yield significantly different results than pouches that include a porous material. In addition, the extensibility of the materials used to construct the pouch can affect the results.
- Test equipment;
- Rate of air flow into the package;
- Sensitivity of burst test equipment (machine response to pressure drop); and
- Whether or not restraining plates are used and, if used, their separation.
Because of the complexity of the stresses that the seal experiences, theoretical models for predicting the correlation between seal strength values as tested via a tensile test (i.e. ASTM F88) and burst value historically have had very poor results. Therefore, empirical studies are the preferred method of determining the relationship between tensile seal strength and burst test values. This can be accomplished through a ladder study where packages with differing tensile seal strength values are created and the corresponding burst strength values determined. Regression analysis can then be employed to characterize the relationship between the values. assuming that high temperature aging properties correspond to room temperature properties.