PERMEABILITY OF TEFLON-PFA TUBING TOWARD CARBON-DIOXIDE

The permeability coefficient for carbon dioxide diffusing through a sample of Teflon-PFA tubing was determined experimentally. The experimental technique employed to facilitate this study involved passing a low flow of pure carbon dioxide, at 7.8 atm (absolute), over the outside surface of a 6.74 m length of the PFA tubing. At the same time a flow of pure (initially) nitrogen was passed through the inside of the tubing. Carbon dioxide permeating from the outside surface of the PFA tubing and into the flowing nitrogen was observed in the effluent gases as they passed through an infrared carbon dioxide gas analyzer. By this means, carbon dioxide concentrations in the effluent nitrogen were determined as a function of varying nitrogen flow rates and at pressures of 4.4 and 7.8 atm (absolute) within the tubing bore. The carbon dioxide permeability coefficient, determined in this way, is 1.53 × 10-8 cm3 (stp) mm/cm2 s Torr. © 1990.