Ammonia Adsorption in Five Types of Flexible Tubing Materials

Abstract

Five different types of tubing materials, namely, polytetrafluoroethylene (PTFE), perfluoroalkoxy (PFA), fluorinated ethylene propylene (FEP), high density polyethylene (HDPE), and polyvinyl chloride (PVC) were evaluated for ammonia adsorption at two nominal ammonia concentration values (1 and 10 ppm) at ~24C. All tubing sections were 2.5 m in length and 4.76 mm in i.d. except the HDPE which had an i.d. of 4.32 mm. Mass balance was used to determine ammonia (as ammonium-nitrogen (N)) adsorbed on the inside of the tubing versus the total N recovered in the tubing plus the gas scrubbers (primary and secondary). No tubing significantly differed in N adsorption. Averaged for both ammonia concentrations, N adsorption as percent of total N ranged from 0.15% (PVC) to 1.69% (FEP). Hence, the least expensive PVC tubing may represent the best option under conditions similar to those used in this study. The gas scrubber design used in this study had excellent trapping efficiency (>99%).