Gas Diffusion
Methodology establishes the steady state rate of oxygen gas passage through plastic films or packaging sheets. Adhering to astm d3985 allows laboratory operators to determine the precise volume of gas migrating through a defined barrier area over a period of 24 hours. The sequence utilises a coulometric sensor to detect molecules that move from the high concentration chamber to the nitrogen carrier gas stream on the opposite side of the sample.
Signal Precision
Detector response quantifies gas flux through high barrier materials with high sensitivity. Accurate calibration for astm d3985 requires stable temperature because gas solubility in polymers varies when thermal levels change even slightly. Equipment maintenance involves checking reference films of known transmission values to identify sensor drift before production lots undergo testing.
Reliable results exclude atmospheric contamination from the carrier gas path to avoid skewed data for low transmission grades. This detection method avoids errors associated with simpler pressure differential sensors that lack specificity for oxygen.
Performance Limit
Barrier selection relies on quantitative flux values reported in standardized units. Within technical specifications, astm d3985 sets the floor for shelf life expectations in modified atmosphere packaging. This benchmark determines the minimum acceptable barrier level for sensitive foods.
