Modelling Gas Transmission in Cylindrical Dynamic Accumulation Oxygen Transmission Rate Chambers to Explore Implications of Oxygen Sensor Location Relative to Samples By Ayman Abdellatief, 1 Bruce A. Welt, 1 * Jason Butler, 2 Eric McLamore, 1 Arthur A. Teixeira 1 and Sanjay Shukla 1 1 Agricultural and Biological Engineering Department, University of Florida, Gainesville, FL 32611, USA 2 Chemical Engineering Department, University of Florida, Gainesville, FL 32611, USA A model was developed to simulate oxygen accumulation in space and time within cylindrical dynamic accumulation chambers that are used to measure oxygen transmission rate (OTR) of materials. The model is based on Fick’s law of diffusion and was validated against actual OTR measurements of polymer film samples. Measured OTR values and thicknesses were inputted into the model and oxygen concentrations outputted by the model. OTRs determined from the output of the model was in close agreement to within 0.3–3% of the measured OTR. Oxygen concentration versus time curves generated from model output oxygen concentrations and experimentally measured oxygen concentrations for three actual films were also in agreement. The model was then used to simulate results from three hypothetical test films at varying chamber lengths in order to evaluate effects of accumulation chamber dimensions relative to films on resulting OTR measurements. A typical design scenario was used, where the oxygen sensor is mounted on the chamber wall opposite the sample film. Results demonstrate that dynamic accumulation OTR instrument designers have considerable flexibility in choosing accumulation chamber dimensions because deviations in OTR are only expected to occur at impractically extreme chamber lengths (>10 m) for the entire envelope of OTRs expected for typical packaging films. Copyright © 2014 John Wiley & Sons, Ltd. Received 5 February 2013; Revised 8 November 2013; Accepted 17 November 2013 KEY WORDS: oxygen; permeation; transmission; dynamic accumulation; D3985 INTRODUCTION Oxygen transmission rate (OTR) of packaging materials is an important parameter for package design. Different products have different oxygen requirements for maximum shelf life. For the case of fresh produce, different products have different respiration rates, bulk densities, sensitivities to minimum oxygen concentrations, etc. and therefore require specific package designs. 1–3 Some products such as flesh foods often require oxygen free atmospheres. 4–8 Accurate knowledge of material OTR plays a key role in successful package design. Several methods are available for measuring OTR. One method is described by American Society for Testing and Materials (ASTM) D1434, 9 in which a sample forms a sealed barrier between two chambers, where one chamber is initially filled with pure oxygen and the other chamber is free of oxygen. The pressure or volume of the oxygen receiving chamber is monitored over time, and the OTR is determined from the change in volume or pressure. This method has been used by several researchers. 10–12 * Correspondence to: Bruce A. Welt, Agricultural and Biological Engineering Department, University of Florida, Gainesville, FL 32611, USA. E-mail: bwelt@ufl.edu PACKAGING TECHNOLOGY AND SCIENCE Packag. Technol. Sci. 2014; 27: 651–662 Published online 7 February 2014 in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/pts.2059 Copyright © 2014 John Wiley & Sons, Ltd.